A/C Kicks Out

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  #1  
Old 10-07-01, 12:06 PM
dancad
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Angry

I've got a 5 ton central a/c unit that has been running fine. The circuit breaker tripped on it today and when reset and the thermostat set to run the unit, the outdoor portion (where the fan and compressor are) do nut start and eventually trip the circuit breaker again

Any ideas

 
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  #2  
Old 10-08-01, 08:14 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi,

It could be a bad breaker or short in main wiring (240 volts)going to outside Condensing unit. Do you have a Voltage Multi-Meter to check voltages? If so, remove panel to outside unit to gain access and look for the larger 2 wires coming from Compressor and going up to the larger electrical component (Contactor). DO NOT ATTEMPT THIS UNLESS COMFORTABLE WITH IT ---- Check where wires (2) are coming to it (Contactor),from where the wiring enters the unit and see if you read 240 volts when set to come on. BE CAREFUL,this is live 240 voltage. If you DO NOT have 240 volts where wires come into contactor from unit wiring entrance,then it's likely the breaker or a short in the wiring.Write back and we'll go from there. Take Care and Best Wishes.

CoolBreeze
 
  #3  
Old 10-09-01, 03:46 AM
dancad
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reply to coolbreeze

as an update. I have a carrier 5 ton unit. When the power is on and the T-stat calls for the unit to operate, the fan on top of the outside condensing unit hums and trys to run. I cannot hear whether or not the compressor kicks on. The unit is pretty simple. There is the large contactor, a capacitor which I had checked this am and is fine and a time delay that I think operates the fan, though I am not sure. There is a local disconnect that has to incoming wires...a black and a white. The white wire has what appears to be some loss of metal where the disconnect "forks" engage and it looks a little wet. In addition, for as long as we have owned the house, whenever the ac kicked on, the lights will dim for a split second and you can hear a slight hum at the breaker panel momentarily.

When I energize the unit now...it lasts for about 30 seconds, then I can hear something click outside and the breaker trips in the panel in the house.

Thanks for the reply

Dan

I will try you recommendations tonight. I have an analog voltmeter and am confident that I won't get zapped.
 
  #4  
Old 10-09-01, 12:14 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Before checking with Meter,make sure outside unit coils are clean,inside unit evaporator coils are clean and filter is clean.Then remove panel on outside and have someone turn on unit while you observe outside unit.This way, you can hear if compressor is starting or trying to and you can look for any electrical arcing (sparks).STAND CLEAR of unit while doing this and turn off at t-stat if anything looks/sounds suspicious.The places to check with meter are where main wiring enters unit and goes to contactor (Larger wires)= 2 wires = 240 volts,the 2 smaller wires going to back of contactor = t-stat low voltage wires = 24 volts.When the t-stat is turned on and unit is calling for A/C,you will have 240 volts at contactor entrance side,then you will receive 24 volts at back of contactor that energizes the coil and pulls in contactor sending the 240 volts across the contactor to the compressor and fan through the capacitor (s),relays, etc... .Check for these voltages and look/listen for contactor energizing/pulling in.You could have a bad contactor,capacitor,disconnect,breaker or short in wiring OR a dirty unit causing the pressure to rise, increasing amperage and kicking out breaker.BE CAREFUL and write back with results.Take Care.

CoolBreeze
 
  #5  
Old 10-09-01, 02:25 PM
dancad
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That's very interesting. We just installed a 3M allerfy style filter a few weeks ago and to say the least...it's doing its job better than any filter we used in the past. I am in Baton Rouge and will get a chance tomorrow evening or Thursday to perform these test.

Thanks again....could it be a shot compressor ?
 
  #6  
Old 10-09-01, 02:48 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Yes, it could be a bad compressor,however,we'll first need to know if the compressor is working or if the compressor and the fan is out. If the compressor went out on overload, it will stay out until cooled down and can kick out the breaker if it continues to try to start. The contactor controls both the compressor and the fan,so it helps to know if one or both are out.How old is the unit and has it been serviced/repaired in last 2 years? You can also turn off power to outside condensing unit (check to be sure it's off---never trust the disconnect) and then trace and disconnect wires going from contactor to the fan only. Turn on power and see if "humm" is still there. This will let us know if it is the fan or the contactor humming. To thoroughly clean outside unit coils,you'll need to remove top or side to be able to spray with water hose back through coils in the direction opposite of air entrance. You will need to first be sure everything is clean and all voltages correct and present before knowing for sure if components are bad.You're doing fine,I'll await your reply. Take Care.

PS: Low airflow (Outside Unit) = rising pressure = rising temperature = Higher Amps = Increase in wire temp = Breaker kicking out. As the pressure rises, it increases the temps which increases the amps and increases the temps of the loads (Compressor/Fan,etc.....). this can cause the compressor to kick out on overload (Too Hot)and as it keeps trying to start,it heats up the wiring and kicks out the breaker. Breakers kick out due to INCREASE in heat temp.,not due to increase in amps.Just simply knowing if compressor is working or not or is trying to start will help tremendously in pointing me in the right direction.

CoolBreeze
 
  #7  
Old 10-09-01, 03:52 PM
dancad
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Here's the latest.

I placed the leads of my voltmeter across the compressor side of the contactor and placed the system on 3 times. The humm is definitely the fan motor. The contactor appears/sounds to pull in, then drop off. On the second try, the voltmeter slowly climbed and the fan and compressor kicked on....hurrah...on the first and third try, the voltmeter never left zero and the contactor dropped out. I shut the power off and tightened by wires on the compressor side of the contactor...one was pretty loose, reset everything. Had 220 V on the line side, 0 one the compressor side of the contactor.

Why would the fan hum if the contactor is not engaged ?

What else can you recommend ?

Thanks again...you have been a tremendous help.
 
  #8  
Old 10-09-01, 05:52 PM
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Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Turn off power to condensing unit (Make sure it's off),then mark first (For later re-connecting) and remove the wires from the contactor. Remove contactor and look up in the middle where contacts pull together and see if the contacts are blackened,burnt,corroded or pitted. If so, and I believe they will be, take the contactor to an Air Conditioning/Heating/Refrigeration Supply House and get a matching one and reinstall and connect wiring back by following the marked wires. From what you described, I believe this should be at least part,if not all of your problem. You may have additional problems steming from this,but this would be a good place to check. Write back and we'll continue. You're doing great and you're welcome,glad to be of help. Take Care, I'll await your reply.PS: Also,with t-stat set to Cool and Auto and 65 degrees,check and see if you're getting 24 volts to the 2 small wires at back of contactor with unit turned on and calling for A/C. If you have 24 volts there and 240 volts at Line side of contactor but 0 volts at Load side of contactor with unit calling for A/C,replace the contactor.You could also push in on the connecting arm across both poles of contactor with something insulated for your protection to see if compressor/fan works with contactor manually pushed in. Man,that was a LONG PS,LOL. Take Care.

CoolBreeze

[Edited by CoolBreeze on 10-09-01 at 09:19]
 
  #9  
Old 10-10-01, 12:21 PM
dancad
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The latest.

The contactor is of and it looks more corroded than anything else. I would guess that 25% of what is supposed to be shiny,,,is....the rest is rusty looking...can it be cleaned or pitched and what is the likely root cause of the rust to begin with

So far....my hair hasn't stood straight up...being very careful
 
  #10  
Old 10-10-01, 02:22 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Did you have 24 volts at back 2 wires (Small) on contactor? We know you had 240 at entrance (Line) side and 0 at Load side.We need to know if the coil was getting 24 volts. You can check this if you haven't yet by placing leads on the 2 small wires that went to back of contactor and turn t-stat to cool, auto and 65 degrees. Leave main 240 volt power disconnect off. You should read 24 volts. Did you manually push in and hold in on the contactor to see if compressor and fan would work? Write back and we'll go from there.Take Care and Be Careful.

CoolBreeze
 
  #11  
Old 10-10-01, 04:09 PM
dancad
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24 V not

there are 2 red wires that come into play here. One red is wire nutted to a brown wire which goes to the contactor. that wire read 5 volts at best.

the second red wire nuts to a blue, which goes to a delay timer, which feeds a violet wire which also goes to the contactor. no volts on the blue or violet

the tstat is a white rogers and it looks like i would need to bust it to get to the right wires.


whats next

dan
 
  #12  
Old 10-10-01, 08:24 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

The two smaller wires going to the back of the contactor are your Low Voltage Circuit wires. One comes from your step down transformer (120 volts down to 24 volts)and goes straight to one back-side of the contactor (Red to Brown to contactor)and sits there.You have another wire (Red),that goes from transformer and eventually makes its way to the t-stat (T-stat Power Wire - Red).When t-stat calls for A/C,The Red crosses over in t-stat to the Yellow (A/C-Outside Unit)and the Green (Indoor Fan/Blower).These wires can go through different components and may be of different colors before reaching their destination and may also be wire-nutted to another wire along the route.Anyway,this second wire (Red in this case) comes from t-stat and makes its way to the time-delay (Safety to keep compressor from cycling on right after going off--Power Outage,etc...)and from there goes to other back-side of contactor to complete circuit. This pulls in coil as it's energized and the 240 volts crosses the contactor. If you have 24 volts at the coil and 240 volts at Line side of contactor and 0 volts at Load side, contactor needs to be replaced.Take it with you for matched replacement.What I was telling you earlier is you can push in on the connecting arm that crosses the poles (contacts) of contactor and manually hold it in (Use insulated tool---not your fingers)and see if compressor/fan comes on and runs. When the contacts become corroded,the coil will pull them in, but they won't hold and seperate. You'll have to re-install contactor to do this.It would not be cost efficient to replace the contactor if the compressor and/or fan is bad. A bad comp./fan can cause contactor to arc and corrode the contacts and the rust comes from moisture and heat from use over time. The time-delay can be from 3-10 minutes depending on its setting.

To check for 24 volts,place one meter lead on the Brown wire from contactor and other lead on the Violet wire from contactor and turn on at t-stat AFTER it's been off at least 10 minutes and with 240 volt Disconnect off (Make SURE 240 volts is off).If ok,you'll read 24 volts.

Write back and we'll continue.Take Care and as always,Be Careful.

CoolBreeze
 
  #13  
Old 10-11-01, 08:42 AM
dancad
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When I read across the brown and the violet. I ended up with 5 volts...only 5 volts.

What next
 
  #14  
Old 10-11-01, 09:12 AM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Jumper over or by-pass the timed-delay switch and test the two wires again. Be sure ALL wire-nuts are tight with good connection,meter leads on ends of Brown and Violet securely and meter set for closest setting at/above 24vac.Write back with results and be studying your t-stat for disassembly.It should have outer snap-on cover and screws to hold 2nd piece to the back subbase.Take Care.

CoolBreeze ---- PS----Did you re-install contactor to check operation of compressor and fan?
 
  #15  
Old 10-11-01, 09:47 AM
dancad
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i don't have the guts to hold that contactor in...it did pull in once the othernite and the fan ran at least a minute before i had my wife shut the unit off.

i will check voltages again as soon as the tstorms stop.

i dod have a wiring schematic if that is worth anything
 
  #16  
Old 10-11-01, 10:06 AM
dancad
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OOOPPPs....i was reading on a Volt DC scale not AC...will check brown/violet agan
 
  #17  
Old 10-11-01, 10:13 AM
dancad
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checked twice.....24 volts ac
 
  #18  
Old 10-11-01, 10:32 AM
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Location: Tennessee
Posts: 211
Breaker kicking out

Hi Dan,

Take the contactor with you and get a matched replacement and reinstall.There may be other problems stemming from this as when these things happen, the increase in amps and wire temps can damage any and everything all the way back to the breaker including the breaker.However,with 24 volts at coil and 240 volts at Line side, you may only need a new contactor.Then you'll know if compressor and/or fan is bad or going bad.Make sure unit is clean, inside and outside,before turning on after contactor is replaced.Also,after contactor is replaced and wires connected,leave disconnect (240 volts) OFF and turn t-stat to Cool - Auto - 65 degrees and retest Brown and Violet wires at contactor for 24 volts.If ok,then turn OFF t-stat and turn ON disconnect and check for 240 volts at Line side of contactor. If you have 24 volts at coil and 240 volts at Line side of NEW contactor,you should be good to go.

When you checked and got 24 volts,were you bypassing timed-delay? If so, try it again w/o by-pass.If you get 24 volts while by-passed and don't w/o by-pass,you'll have to take it with you for a matched replacement also.

When you start it up,be ready to turn it off if it doesn't start,look or sound right.

I'll await your next post.Take Care and Best Wishes.

Contactors here are $10-20.00.Be sure it matches and has a 24 volt coil.Also,make sure ALL wires are tight and replace any that are burnt or damaged with same size wire and connectors.

CoolBreeze
 
  #19  
Old 10-11-01, 10:48 AM
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Posts: 186
If it were me I would replace the capacitors while I was doing all this. If the unit is more than 7 or 8 years old they are about due anyway. Shouldn't cost more than 20 or 30 bucks, if that. What kind of unit is this anyway? My Trane units had some funky compressor contactors, didn't last long.
 
  #20  
Old 10-11-01, 10:52 AM
dancad
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24 vac w timer by passed and 24 vac w/o timer by passed.

The contactor pulled in and buzzed in all cases

I also checked each of the leads to the compressor and fan motors to ground and found 0 ohms

even though the contactor is bad, would it still pull in ?
 
  #21  
Old 10-11-01, 11:28 AM
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Location: Tennessee
Posts: 211
Contactor Buzzing

Yes,it could still pull in,but either not make good contact for full voltage flow or not hold and release.Take it with you and replace with a matched contactor with a 24 volt coil.Take Care,I'll await your reply.

CoolBreeze
 
  #22  
Old 10-12-01, 01:27 PM
dancad
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wow

ge supply has a contactor that may match, i'll know monday...60 bucks

can i jump 220 over the contactor to make sure the rest works
 
  #23  
Old 10-12-01, 01:59 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

Different States,unit sizes and contactor types create different prices. Most of the units here are typically 2.5 - 3 tons. Just be sure it matches and has a 24 volt coil and make sure it's the right size to fit in the space where it goes. Yes, you can bypass/jump it,but ONLY if you can connect ALL wires securely. Untight connections can/will cause arcing and damage components and wiring.

It's easier to re-install "old" contactor and reconnecting the wires.Before doing this,look/study contactor to see how the contacts pull in. Look for the arm across the poles that you can push in to close contacts. Once installed with power OFF,Take a long screwdriver or nutdriver with a good insulated handle and push arm all the way in tight and hold steady with contacts in closed position.Have someone turn on power and just hold tight in place and see if unit starts and runs.Have unit turned off at disconnect/breaker when ready as contacts may stick together and not release.Practice this with contactor "off" unit until comfortable with it. All the wires coming off the contactor would have to be spliced to the right wires to complete all circuits if you jumper it and could cause problems if you splice the wrong wires together.Write back whatcha think.

Take Care,
CoolBreeze
 
  #24  
Old 10-13-01, 03:42 AM
dancad
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I pulled the contactor back off and took it apart. The 24 V side...there are 2 outer strips with the bigger block in the middle. The outer blocks look worse than the middle when it comes to corrosion/wear. The 220 v side...the two bars look ok. The dots that they make contact with are pitted and look almost silver like.

Can this be cleaned. I am gutless when it comes to sticking a screw driver in there
 
  #25  
Old 10-13-01, 09:01 AM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

Yes,they can sometimes be cleaned,however,it usually doesn't last long once they have started corroding and pitting. The downside from what it's doing now (Contacts not holding together) is the contacts can stick and not release and cause the unit to not shut off. This can severely damage unit if not found and corrected soon enough.

I would strongly,but nicely,suggest you replace the contactor rather than cleaning it. You might also shop around some, you should be able to get one w/o waiting and possibly at a lower price.Unless the compressor and/or fan caused this OR this damaged them, you should be ok. I'm not there,but I believe the contactor will solve your problem or at the least, most of it. Take Care and I'll await your reply.

CoolBreeze
 
  #26  
Old 10-14-01, 12:31 PM
dancad
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i called the carrier parts dealer saturday and will pick up the contactor monday. a couple of other thoughts

Last year we found that the compressor had actually iced up. the fan and compressor ran for quote a long period of time before we figured out that something wasn't right. my wife woke me up one morning and told me that the fan ran all night and that didn't sound right. it wasn't. I shut the power off and turned it back on and it worked ok since this latest incident.

around the time that this most recent blip happened, i was lying on my floor on my laptop and felt/heard a humm...felt like something was humming under the carpet/concrete slab ????

We'll hook up the contactor and let it fly

thanks

dan
 
  #27  
Old 10-14-01, 07:01 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

The reasons units ice/freeze up are dirty Inside Evaporator Coil,Filter(s),Fan/Blower Motor,Blower Wheel (Squirrel Cage),Return Air Grate/Cover,Fan/Blower not working,Return Duct Work loose,seperated or kinked,blocking/releasing airflow,Low Refrigerant charge (Leak),Liquid Line Restriction,T-Stat set too low,Stuck/Fused contacts on Contactor (Unit won't shut off). If this happened last year only once and ran fine since,the only reason that could "fix" itself would be "Stuck Contactor" and this would eventually happen again. When the contacts become corroded/pitted, they either won't hold or hold and not seperate and sometimes both until it finally stops on one or the other.

As for hummm under the floor????? What's underneath the floor,ie: equipment,etc.... ?

Replace the Contactor (Remember to make sure it has a 24 volt coil) and look/listen and check it closely to see if it seems ok. Then,after a couple hours of normal (Hopefully) operation,let it run for 20 minutes and then take a good/accurate thermometer and get the temp. at the closest return air grille/register to the Inside Evaporator Coil and then get the temp. at the closest Supply Air grille/register to the Inside Evap.Unit and post them for me. Also post the Indoor Home temp. and Outdoor temp. at this time. Do this at hottest part of day as possible to have best heat load on unit.

If anything is not right or looks/sounds wrong, turn off unit.Write back with results and we'll go from there.Be sure ALL above items on freeze ups are covered and cleaned/repaired if needed.This is about all you can do,if there is additional problems due to this situation, you may need a Contractor to perform a system operation check on unit to keep from further damage.Small problems unnoticed can lead to additional problems.Hopefully you have caught this in time, but I'll stick with you as far as you're knowledgeable and equipped enough to go.Take Care and Best Wishes.Take your time,triple check EVERYTHING and of course,BE CAREFUL. You have done great so far.

Sincerely,
CoolBreeze
 
  #28  
Old 10-15-01, 05:51 AM
dancad
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New Contactor

CoolBreeze:

Here's the latest

I sourced the contactor through the local hvac company that installed the unit when new and they directed to a parts supply house that matched the original to a Mars contactor. The specifications (amps, 24V coil, hertz) all match the original and from what the hvac vendor told me, this is the part they would have installed if I had called them for service.

The 220 V in and out are cool...I can wire that up identically. The biggest difference is the 24 volt piece. The original contactor has the 2 female connections on to. This contactor has 2 sets of 2 female connections...one set on each side of the contactor...do i simply hook up the two 24 volt wires on one of these sets or what.

The other difference is the 24 volt coil...the new part has an actual copper wire/wound coil..the old one has a magnetic deal...looks different

Cost of the part $16.00

Do you see any reason why this part would not work ?

Dan
 
  #29  
Old 10-15-01, 09:49 AM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

They come in diff. shapes, sizes and looks. The copper wound coil "Magnetizes" when energized to pull in the contacts which are made of "Magnetic" material.They look diff., but are all alike in the manner of operation. They have diff. coil voltages,amps ratings, etc..., so all you have to do is make sure they match and you have done that.

On the coil,you connect "One" wire to one side and the other wire to the other side.Just act as if there is only one terminal on each side and connect the wires just like the old one. It doesn't matter which terminal you choose on each side,just connect "ONLY" one wire to each side. I always connect to the two "Back" terminals,one on each side.Do that and the other items above and I'll await your reply.Take Care and I'm now able to catch my breath knowing it is "Only" $16.00 rather than $60.00.

CoolBreeze
 
  #30  
Old 10-15-01, 12:15 PM
dancad
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I wired up the contactor and nothing changed. The power when turned on at the disconnect shows 220 coming in.

When my wife turns the tstat down, I can here the contactor click, I will measure to make sure we have 220V the next try.

I have to come back to the wiring for the 24 volt circuit. The contactor I have is Mars. There are lugs top and bottom and there are copper females on top and bottom as well.

The females that I am assuming are for the 24 volt are silver looking with two females on a solid plate on each side...do I have that hooked up right ?
 
  #31  
Old 10-15-01, 12:25 PM
dancad
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voltage to fan motor

CoolBreeze....while awaiting your next reply, I checked the 220V incoming and both legs are at 220V. There is a connection on the incoming side of the contactor that goes directly to the motor, which is humming still and is getting warm to touch. That feed is measuring about 110-120 volts...is that correct ?
 
  #32  
Old 10-15-01, 01:12 PM
dancad
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trial and error

The fan motor runs fine when i disconnect the compressor wiring from the contactor and the capacitor.

When I disconnect the fan motor wiring and energize the system, the breaker disconnects at the panel in the house

Is this starting to sound like a bad compressor and if so, what checks can be done to confirm ?

We had a power failure the day this all started and I wonder if this is related. Is there a fuse or anything in the compressor motor that I can replace ?

Thanks

Dan
 
  #33  
Old 10-15-01, 07:55 PM
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Join Date: Mar 2001
Location: Tennessee
Posts: 211
No A/C

Hi Dan,

I'll try to see if I can detail some indo for you to try and cover everything w/o my being able to see it. Try each step I list to the letter and in order given.

1- Go back and carefully make sure each wire is connected at same place as old contactor and all are tight and undamaged.
2-You'll have two lugs top and bottom,other assorted ammount of terminals on each side of contactor near front on top and bottom and either one or two terminals on each side toward the middle back area,close to coil kind of by themselves. Those are your 24v coil terminals and you put one wire only to each side. Those other side terminals near front area are 110-120v each and go through the relays,capacitors,etc.. on way to load components.
3-Turn off disconnect and turn on t-stat and check coil wires,one meter lead to each wire to see if you have 24v.
4-Turn off t-stat and turn on disconnect and check incoming line side of contactor only for 220-240v.
5-If you have the 24v to coil and 220v to line side in above checks,turn on disconnect and have your wife turn on t-stat.Listen for contactor to pull in and check for 220v on outgoing load side only of contactor for 220v.If 220v is there go to next step, if not,with ALL power on, recheck coil and line side of contactor now.
6-Did the compressor and fan start or attempt to start.If either fails to start,turn off ALL power asap.All power equals disconnect and t-stat.

You stated Fan was humming and getting warm, was this with all power on and unit coil energized and if so,what was compressor doing at this time? Has the compressor ever started? You may have a bad breaker, capacitor, relay,etc.. . Like I stated earlier, when you have an electrical problem such as this and unit tries to start, the heat generated goes through the wiring and can/will damage other electrical parts.If the compressor is not starting at all, not even trying or trying with no success,check to see if it is getting power at the compressor terminals.Look also around the area where the main wiring comes into unit from disconnect to see if you see a small red reset button.Also look closely for unconnected,damaged or burnt wiring.

Cover these and write back with readings.How many capacitors does the unit have? You stated previously you had checked the capacitor. Detail this check to me per what you did and what was results? Also,is everything clean as advised earlier? Sorry for all the repeat questions,but I have to ask since I'm not there to see it.Also,give me the make of unit,model and serial numbers and age of unit.

Take Care and I'll await your reply.

CoolBreeze

[Edited by CoolBreeze on 10-15-01 at 11:43]
 
  #34  
Old 10-16-01, 05:52 AM
dancad
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Information that May help

1). The unit is a 5 Ton Carrier - I'll send the model number later today
2). The unit is 7 years old. It was installed new at the time we bought the house/also new
3). We had it serviced about 5 months ago, prior to the summer season getting into the peak. Nothing was found to be in error. Only change the fella made was to install about a 6 " section of PVC off the condensate drain line in the attack that points straight up like a chimney
4). I checked the pan high level switch...there is no water in the pan at all and the switch looks/feels ok
5). Thus unit has a single capacitor. It look like an ignition coil in a car. There is a single wire (yellow) that is on the incoming side of the contactor which goes directly to the "C" connection on the capacitor. There are two outgoing connections from the capacitor. One stamped "herm" and this is a blue wire that I can trace all the way to the compressor motor. The other is a brown wire stamped "fan" on the capacitor which goes to the fan motor.
6). I asked a fella at work to test the capacitor. I don't have a clue how to do that. He took an analog voltmeter (mine) and tested each connection on top of the capacitor using the ohm meter. The needle moved slowly/slightly towards "0" then came back to full scale ohms. Each of the 3 connections behaved this way though all were slightly different. None of the 3 went all the way to "0". After he checked it, I read an online guide that said that each should have gone all the way to "0" first.

Secondly, when I handle this, am I in danger of getting zapped even after I full all the wires off of it

Do you have a recommendation for testing

7). I do have a wiring schematic and the old contactor and am fairly confident that I have the wiring correct

8). The fan humm and getting warm/hot is with the panel breaker in "on", with the disconnect in "on" and the tstat in "off". I walked past this unit a bunch of times in the past and never noticed that it ever hummed before when not running. I check my neighboors (a Rheem) and found nothing similar there. The only power would be from the yellow wire to the capacitor then to the fan motor. The other fan power comes from the unit side of the contactor.

As I wrote yesterday, when I pulled all of the wiring associated with the compressor off of the contactor and we turned everything on, the fan started and ran like always. The 24 volt wiring was in place, the yellow wire from the line side of the contactor to the capacitor, the brown wire from the capacitor to the fan and the other fan wire(s) from the unit side of the contactor

When we did the opposite (disconnected the fan and left the compressor side connected)...we heard the breaker trip within seconds after the wife dropped the tstat on.


I will follow all of your recommendations later today. Afterall...the weather is cool this time of year and my mother in law is paying a visit...I am in no rush and spending the time outdoors versus in is good for my health right now...physical and mental


I cannot believe that the compressor is bad

I also have a pressure gage for my cars HVAC...if the fitting is compatible, is it worth checking the pressures ?

Thanks again...we're gonna get this sooner or later

Dan
 
  #35  
Old 10-16-01, 11:26 PM
Member
Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

With the comp. wiring off and fan wiring on,Fan runs fine. With fan wiring off and comp. wiring on ,Breaker inside kicks out. What does the Fan, Compressor and inside Breaker do with ALL wiring connected and ALL power on? Hook everything up,turn ALL power on and check at coil for 24vac,line side of contactor for 220vac and load side of contactor for 220vac. If you have all 3 of these with correct voltage,IS the compressor starting or trying to? If not,is it getting 220vac at the compressor terminals?

If you have 24vac at coil,220vac at line side and load side of contactor with contactor pulled in and 220vac at compressor AND compressor is not starting/running, your compressor MAY be bad. If you don't have 220vac at the compressor,your capacitor MAY be bad. Without being there to actually see it and going by info given, I believe you either have a bad capacitor or a Locked Rotor in your compressor. It is very IMPORTANT that I know what, if anything, the compressor is doing.

I also need your model and serial numbers asap.Write back with above info and DO NOT run unit anymore after taking those readings due to possibility of causing irreversable damage to unit if there is additional unknown problems.

I'll await your reply.Take Care. Also,yes the needle should have swung all the way over to 0 ohms when testing capacitor and YES,touching the capacitor even with power off can shock you and/or kill you.As I have said before,BE VERY CAREFUL!!! The capacitor can HOLD its charge and be very dangerous.

CoolBreeze
 
  #36  
Old 10-17-01, 04:36 AM
dancad
Visiting Guest
Posts: n/a
Model Number, Serial Number

CoolBreeze:

One other thing I want to tell you, with everything hooked up, i mean everything, the voltage from the capacitor to the fan (single brown wire off of the capacitor) only read around 110-120 volts....this was without turning the system on at the tstat....why wouldn't this be the full 220 volt for that leg from the capacitor to the motor ? Or better yet, why is there juice at all

The unit is a 5 ton carrier

Serial Number 1994E02084

Model Number 38CK060310

One other note....I pull the circuit breaker panel off last nite and looked at the 40 amp breaker for the ac...everything looked ok...nothing appeared to be black/sooty or burned at all


LASTLY, I DON'T KNOW IF THE BREAKER WILL STAY ON LONG ENOUGH TO MEASURE THE VOLTAGES AS YOU HAVE REQUESTED...I WILL TRY AND REPORT BACK

I messed around with that capacitor quite a bit, lucky i didn't get zapped

Thanks again (especially for the patience)

Dan

 
  #37  
Old 10-17-01, 05:19 AM
Member
Join Date: Mar 2001
Location: Tennessee
Posts: 211
Contactor

Hi Dan,

Turn off power at disconnect and check to be sure it's off at line side. Then disconnect the 3 wires from the compressor terminals,seperate them good so they can not touch each other or any other unit parts and so you can place your meter leads on them for voltage check.This removes compressor from circuit.Do not take anything else loose.Then turn on All power (Breaker,Disconnect and t-stat)and then check for 24vac at coil,220vac at line side,220vac at load side and 220vac at the ends of the compressor wires.Listen for contactor to pull in and observe/listen to Fan motor. Do these as quickly as possible and turn back off.This will tell me what I need to know w/o the Breaker kicking out.

Does the Breaker kick out EVERYTIME the unit is started WITH the compressor hooked up? If so, does it do it so fast that the compressor never gets a chance to start or does it attempt,then stop?

There should not be any live voltage going to Fan motor with unit off.

Do you know anyone who has a Clamp-On Amp Meter with a Digital Readout and a Hold setting?

Do these and write back.I'm almost there,it sometimes takes a little time w/o my being there to see it.Take Care and BE Very Careful.

CoolBreeze
 
  #38  
Old 10-17-01, 12:13 PM
dancad
Visiting Guest
Posts: n/a
I've seen everythong now

I disconnected all by the incoming feeds and the 24 volt on both sides of the coil

I don't have 24 volts to one side of the coil. The wire that comes from a red incoming to a violet outbound.

The red wire that leads to a brown 24 wire has 24 volts


The incoming main to the disconnect is only reading 120 volts to each leg, same on the outbound at the unit side of the contactor

I don't want to go past this until I hear from you. This is the first time I have measured the voltage this closely against a ground wire, positive lead to the incoming feed...negative to a ground

The breaker may be tripping due to overcurrent due to low voltage ?

Dan
 
  #39  
Old 10-17-01, 01:07 PM
Member
Join Date: Mar 2001
Location: Tennessee
Posts: 211
Electrical Troubleshooting

Hi Dan,

When measureing these voltages, do the following:

1 - On Contactor Coil - Place ONE meter lead on one wire where it connects to the contactor and the OTHER lead on the other wire on the other side. You should read 24 vac with all power and t-stat ON --- 0 vac with t-stat OFF.

2 - On Line Side of contactor - One meter lead on one leg and the other meter lead on the other leg where they connect to the contactor --- You should read 220 vac with disconnect and Breaker ON ---- 0 vac with disconnect OFF.

3 - On Load (Outgoing) side of contactor - One meter lead to one leg and other meter lead to the other leg where they connect to the contactor --- You should read 220 vac with ALL power ON and t-stat ON and coil pulled in ---- 0 vac with t-stat OFF.

4 - On the end of wires from Load side of contactor that connect to the compressor - One meter lead to one of the wires from contactor and the other lead to the other wire from the contactor --- You should read 220 vac with ALL power on, t-stat on and coil pulled in --- 0 vac with t-stat OFF.

5 - On the Disconnect - Place one meter lead to one leg incoming and other lead to other leg incoming -- You should read 220 vac with Breaker turned on and 0 vac with Breaker turned off.

6 - On Disconnect - Place one meter lead to one leg outgoing and other meter lead to other leg outgoing --- You should read 220 vac with all power including disconnect on and 0 vac with disconnect off.

On ALL these checks for 220 vac,with the power on,you'll read 220 vac across both legs and 110 vac from each leg to ground. Each leg is 110 vac (No neutral on 220 vac) = 110 vac + 110 vac = 220 vac.

On the coil you'll read 24 vac across both wires AT contactor with Breaker and t-stat turned ON and 24 vac from wire coming from t-stat to ground and 0 vac from other coil wire to ground.

ALL of the readings you listed were correct. Follow this post and my last 2 or 3 exactly as written after carefully reading them and write back with the results.You're doing fine, I'll await your reply. Take Care and Be Careful.

CoolBreeze
 
  #40  
Old 10-17-01, 01:28 PM
Member
Join Date: Mar 2001
Location: Tennessee
Posts: 211
Electrical connections

Hi Dan,

Go back to your original post at top of page and count down to YOUR 6th post. You stated you had a Red wire-nutted to a Blue that goes to the Timed-Delay and then a Violet that goes from there to the coil. You had another Red wire-nutted to a Brown that went straight to other side of coil.

Make sure these are wired back like this. Your wire coming from the t-stat has to go through the timed-delay and the wire coming from the transformer goes straight to the coil.

Look closely at your schematic to BE SURE ALL wires are back where they should be.Do this before checking voltages.

CoolBreeze
 
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