Central A/C Compressor/Condensor/Fan Not Turning On

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  #41  
Old 06-04-12, 08:35 PM
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Good gravy, it's 11:30 & my plate for tomorrow is overflowing already. I have to get some shut eye. I'll check back tomorrow night. I think we can make that single pole work but if you had a double pole as spec'd & hooke it up according to the diagram, she'll work. G'nite.
 
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  #42  
Old 06-04-12, 08:38 PM
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agreed with grady!...........................
 
  #43  
Old 06-04-12, 08:42 PM
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Aha!

Old Contactor was installed this way:

T1 L1
T2 L2


New contactor is installed this way:

L2 T2
L1 T1


I imagine this is the problem....


Whaddya think?

By the way, the lettering is very small and would be upside down if I instaled it to match the old one. I guess contactors don;t care about right side up or down.
 
  #44  
Old 06-05-12, 05:31 PM
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I'm back at it...

Flipped the contactor over to the right way. Now it is behaving just like it did before I replaced the contactor...thermostat turns the blower on, but the condenser does not engage, (argh!) When I push the plunger in, the condenser turns on.

I have 25V coming from the thermostat wires when the blower in on, zero when it is off.

I know the problem is the simplest of things and am 98% there. i just need to find that goof y issue. I thought for sure it was the "upside down" thing., but apparently not.

Who's ready with their thinking caps?
 
  #45  
Old 06-05-12, 05:41 PM
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I hate to think you have a bad contactor but anything is possible. Kill the power to the condensing unit & turn your t-stat off or well above room temp. Disconnect the low voltage wires to the contactor & check across the low voltage coil (one probe on each side) for continuity. No continuity = bad coil.
 
  #46  
Old 06-05-12, 05:49 PM
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Just checked, based on your suggestion. Continuity is good.
 
  #47  
Old 06-05-12, 05:52 PM
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I know this might sound crazy but you do have the thermostat wires on opposite sides of the contactor, do you not?
 
  #48  
Old 06-05-12, 06:02 PM
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At this point, nothing is crazy... and maybe not.

There coil has connectors on top and below. The thermostat wire is brown with red and white conductors. The red and white conductors each connect to a yellow wire, one which connects to the bottom connector, the other connects to the anti cycle timer(?) which has a thick yellow and gray wire coming out of it. The thick yellow connects to the top connector and the gray connector connects with the thin yellow on the bottom.

Y (thick)
t1 L1

t2 L2

Y (thin) Gray (thin)

So do I? Not sure of much anymore.
 
  #49  
Old 06-05-12, 06:09 PM
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Sorry. The junk on the bottom was supposed to be a diagram.

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  #50  
Old 06-05-12, 06:15 PM
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Pull the grey & the thin yellow. Put a probe on each one & check for continuity.
No continuity = open switch. Could be the anti-cycle, the low pressure, or high pressure switch. If you do get an open, we can check one at a time.
 
  #51  
Old 06-05-12, 06:21 PM
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OK...Now we're getting somewhere.

Open circuit between thin yellow and gray wire.

What's next step to test?
 
  #52  
Old 06-05-12, 06:28 PM
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If the yellow to the anti-cycle timer has a plug on terminal, pull it & check for continuity from thin yellow (contactor end) to timer end. If no continuity, you have an open pressure switch (either low or high [most likely low]).

If not a plug on, cut it & strip back enough to get your probe on. Be sure not to cut so close to the timer where you can't spice it back together.
 
  #53  
Old 06-05-12, 06:42 PM
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Not sure what you are telling me to do.

The break timer switch has three wires connected...thin yellow, thick yellow and gray. Which yellow should I pull? Am I checking the continuity at the end of the yellow wire (that was connected to the break timer) or on the timer itself where it was connected?

I imagine a "break timer" is the same as an "anti-cycle timer." right? The schematic says 'anti-cycle' the unit says "break."
 
  #54  
Old 06-05-12, 06:48 PM
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I read that again and I think I know what you are asking.

I ran continuity from the end of the thin yellow wire (not the the contactor itself), to the terminal lug on the break timer switch with the thin yellow disconnected form it. Open circuit.

So bad pressure switch. Which box is a pressure switch? There is only one other box in the panel....
 
  #55  
Old 06-05-12, 06:55 PM
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Photo:

Break cycle unit is on top. Pressure switch(?) below.

Shiny new contactor in background.

The only other component is the capacitor.

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  #56  
Old 06-05-12, 07:05 PM
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Bummer. I'm afraid you are going to have to call a tech. The pressure switches are likely down near the compressor, under the fan. If the low pressure switch is open (most likely), either the switch itself is bad or you have lost refrigerant pressure. A tech could tell if you've lost refrigerant simply by putting a set of gauges on the unit.
Here, we are not allowed to tell you how to check pressures or do anything to the refrigerant side of the system.

Wait a second, if the terminals are marked 1,2, & 3 on the break switch, you need to pull 1 & 3, jumper them together, then check continuity between the yellow & grey which were paired together at the contactor.
 
  #57  
Old 06-05-12, 07:09 PM
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That white block is a pressure switch. Pull all wires & check for a closed switch (continuity across terminals).
 
  #58  
Old 06-05-12, 07:11 PM
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OK...that is the fan speed control. Pressure switch is on the freon lines inside the condenser, not the control panel.

Several years ago, I had an issue with blower mechanism and the ultimate solution was a pressure switch. I couldn't figure out at all which pressure switch was right to replace the defective one. I ended up calling the pro, who charged me $200 for the visit, labor and switch. It wasn't a bad price to pay, but it was an ignominious ending considering all the effort I made to diagnose and repair it, not to mention the grief I got from my beloved spouse.

So how can I tell which pressure switch(es) are the right one(s) to replace the defective pressure switches?

I don't want the same ending as last time.

Thanks so much for spending your evenings with me. I hope it's not in vain.

Allen
 
  #59  
Old 06-05-12, 07:22 PM
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OK, I understand better now. That fan speed switch causes the fan to "change gears" in response to pressure change. Gotcha. Man, some of this online troubleshooting can be tough when we can't see the whole unit but we'll get thru it. I'm here because I enjoy helping folks & a challenge every so often.

The only way for you to check which switch is bad is to remove (or snip & strip) the wires on each switch & check for a closed switch. The switches are probably brazed onto the copper lines. Take a look & let me know.

If the low pressure switch is open, you still don't know if the switch is bad or you've lost refrigerant.
 
  #60  
Old 06-05-12, 07:25 PM
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"Wait a second, if the terminals are marked 1,2, & 3 on the break switch, you need to pull 1 & 3, jumper them together, then check continuity between the yellow & grey which were paired together at the contactor."

The break terminals are not marked 1, 2, 3, but they are L1 -load [thick yellow], C1 -control [thin yellow] and common [gray]. I pulled the yellows, o=connected them with a jumper and tested for continuity between the yellow and gray who hang out together on the bottom of the contactor. NO CONTINUITY!

Could that mean that the answer is a new break timer switch?

I will check on the "white box" but I'm not sure how to check continuity between three terminals. Advice?
 
  #61  
Old 06-05-12, 07:40 PM
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Grady, you are doing great here.

Help me understand how to check these last couple switches.

As you can see I checked the break timer the way you said and got no continuity.

As for the fan speed switch, I doubt that is the problem as the unit won't turn on when it is supposed to. If it was the fan speed switch, there would be speed issues, not turn-on issues, right? Or am I all wet? (I am all wet, really. No A/C in South Carolina is a very bad thing).

I also doubt there was refrigerant loss. The A/C worked great until it no longer started. The compressor works when the contactor plunger is pressed, it just doesn't turn on when it is prompted by the thermostat.

Here's another question: Could the problem be how it is connected to the thermostat? The thermostat wires that connect to the condenser source from the the circuit board on the blower unit. There are several connectors across the bottom labeled G W C Y R. The thermostat wires are connected to the "Y" and "C". The red thermostat wire connects to the Y and the white to the C.

*sigh*
 
  #62  
Old 06-05-12, 07:40 PM
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Allen,
Please forgive me. I've been telling you wrong. That's what happens when I trust my memory rather than going back & looking at the diagram.

The two wires you should be looking for continuity on are the one marked "BL" & the yellow ON THE OPPOSITE SIDE OF THE CONTACTOR.
 
  #63  
Old 06-05-12, 07:43 PM
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Y & C are correct & it makes no difference which connects red or white other than the "C" needs to go directly to the contactor & on the same side as "BL".
 
  #64  
Old 06-05-12, 08:16 PM
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No problem, man. You are putting in extra effort here.

Checked the yellow (thick on top of contactor) and the BL (which is really gray) for continuity. NADA.

Then I got really excited about the thermostat wires...I had the C going the wrong way! I switched them and...no difference. Guh. I really thought that would be the trick.

What next? I only have you for 15 more minutes.
 
  #65  
Old 06-05-12, 08:32 PM
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If you check between the two Yellows, when disconnected from the contactor & there is a call for cooling from the stat, do you get 24 volts?
If you do, something is really screwy because the contactor should pull in.
 
  #66  
Old 06-05-12, 08:39 PM
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No voltage across the yellows.
 
  #67  
Old 06-05-12, 08:46 PM
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One wire from indoors goes to the yellow which shares a terminal with grey, right?

Where does the other wire from indoors connect?

You should have 24v between those two.
 
  #68  
Old 06-05-12, 08:54 PM
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Other leg goes tot he Break Timer. 26.85V between thin yellow on contactor and yellow at break timer.

Bad break timer?

My unit is an EAC-426. I found them on ebay, but I'd rather get it locally and save (yet another day) of unneeded suffering. Could I find it at a local HVAC supplier? Can I use a different model?
 
  #69  
Old 06-05-12, 08:59 PM
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Try jumpering thick yellow to thin yellow at the timer. If the contactor pulls in, you have a bad timer. Also if you have a digital t-stat, they all have delays built in thus negating the need for one on the condensing unit.
 
  #70  
Old 06-05-12, 09:05 PM
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I got really hopeful there for a second.

Jumpered between the two yellows that attach to the break timer an turned the stat to cool.

Blower unit comes on...condenser sits idle, mocking me.

Not the break timer switch.

It's midnight, I'm game, but are you still in it tonight? Should we try tomorrow? I'm close to giving up.
 
  #71  
Old 06-05-12, 09:18 PM
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That whole timer, low pressure switch, & high pressure switch mess is simply a series circuit.
Power goes from the incoming wire to the timer, from the timer to one pressure switch, thru that switch & on to the next; from the incoming side of the second pressure switch power goes thru that switch & out to the contactor.

If you really want to trace it, you will have to keep one probe on the common side & follow the circuit one switch at a time until you loose power. I wish you all the luck in the world but I have to go to bed. 5:30AM comes earlier & earlier every year. I'll check back with you tomorrow evening.
 
  #72  
Old 06-06-12, 04:50 PM
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Latest update:

I was telling my tale of woe to a friend when I learned that a friend of his is a licensed HVAC guy. He called the friend and they are heading over tonight. I'll be sure to show them this thread and get back to everyone with what we learned.
 
  #73  
Old 06-06-12, 05:08 PM
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I really hope it gets figured out...let us know the outcome.

Remember..no "thank you" brews until afterwards.

Can't imagine no A/C in your area this time of year.
 
  #74  
Old 06-06-12, 05:16 PM
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Wiring seems right except for the single pole contactor which shouldn't be a big deal. After all we've been thru the past couple of nights, I really, really want to know what ails this beast.
 
  #75  
Old 06-06-12, 05:21 PM
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Me too.

The single pole contactor was listed on several websites as a direct replacement for my unit. I guess one got it wrong and the others copied it.

I'll keep everyone posted.
 
  #76  
Old 06-06-12, 05:27 PM
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Most equipment today comes with single pole contactors. The diagram on yours shows a double pole but I see no reason why a single wouldn't work.
 
  #77  
Old 06-06-12, 06:48 PM
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Friend of friend came by tonight...turns out he was from the same city in NJ in which my dad was raised.

He poked around a bit, complimented me on the knowledge I could impart, for which I deflected to my online friends...without you guys, I know nothing.

Drum roll....

A/C works!

It turns out that bypassing the break timer switch solved the problem. Connecting the the other leg (thin Yellow) of the 24V to the top side of the contactor started her right up.

So pleased!
 
  #78  
Old 06-06-12, 06:50 PM
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great news! So FYI, with a modern digital thermostat you dont need that time delay! They have a built in 5 min delay on break timer.
 
  #79  
Old 06-06-12, 06:52 PM
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If it works...thats the bomb....so you now need a switch...?

Lets see..you spent less than $100 so far...are you ahead?
 
  #80  
Old 06-06-12, 06:55 PM
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Glad you got 'er going. Bypassing the timer is what I was trying to do when I had you jumper the two yellow wires from the timer together. I hope he hasn't taken the pressure switches out of the loop.
As hvactechfw said, with a digital thermostat you don't need the timer anyway. If your stat isn't digital, I suggest getting one.
 
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