Last night I lowered the thermostat to 73 and like normal 5 seconds later the fan and compressor on the outside unit kicked on and started cooling the house. Well at about 5:00am while still in bed I noticed that the ac unit was running longer than normal, so I got up and noticed that the air was not cold coming from the vent. Having a Rheem unit I noticed that the outside unit was not as loud as normal telling me that the fan was on but not the compressor. Thinking that maybe the unit was froze up I set the thermostat to the OFF position for an hour, seeing if the lines might thaw out, and upon turning the thermostat back to the ON position I might be able to get the compressor to kick on. When I turned the Thermostat to the ON position, the outside unit fan kicked on immediately (Without the normal 5 second delay) which normally occurs.

With this information given above, what do you guys think I should check for first?

 

You need to confirm whether the compressor is in fact running or not. To do that, you'll have to go outside and listen to the outside unit (with the thermostat calling for cooling). In addition to listening to the sound, you can also feel the two copper pipes running between the outside unit and the house. The larger of the two pipes should have some insulation around it, and the pipe should be cold if the compressor is running normally. If the larger pipe isn't cold, it's a sign that the compressor isn't running or is very low on refrigerant.

If the compressor isn't running, you don't have to worry about the evaporator being frozen. BTW, if the evaporator coil was frozen, it would severely restrict the airflow coming out of the vents (very little air would come out). If the evaporator coil were frozen, it would also take much longer than 1 hour for it to unthaw. The quickest way to unthaw it, should it ever freeze up, is to leave the A/C turned off but the fan turned on. That will try to force warm air through the frozen coil.

If you find that the compressor isn't running, but the condenser fan is running, there are two things to check. First, check the start capacitor for the compressor. It may be a single capacitor, or it may be part of a multi-section capacitor. It's often in the range of 45 mfd. If the capacitor looks bulged (usually around the top), it's probably bad. It can also be bad even if it looks fine. Since they are relatively cheap, it's the first thing to try.

If you replace the capacitor and the compressor still won't run, then it's time to check the compressor wiring. The compressor pulls a lot of current, particularly when starting. If you have a loose connection where the wires attach to the compressor, they can get very hot and the terminals can "burn out".

Be sure to turn off the power to the outside unit before doing any work on it. Turn off the circuit breaker and pull the outside disconnect as well. If you have a voltmeter, check to make sure that there is no voltage present inside the unit. Discharge the capacitors before touching any terminals.

 

That's supposed to be a 5 minute delay. The delay keeps your compressor from short cycling.

If the compressor isn't starting then that's the problem that needs to be addressed. You need to make sure that when the fan comes on in the condensor unit that the compressor isn't starting. Then you will need to check the capacitors for the compressor as a first step. Be sure to turn the power off to the condensor unit when working inside.

 

First guys I would like to thank you for your quick replies.

I may have some information to help you further. I turned the thermostat to the ON position and lowered it below the current home temperature, after taking the cover off the outside unit. The compressor is differently not running. However, while I was outside I keep noticing there was a buzz sound followed by a click, which shook the red and black wires coming from the house to the contactor. (by the way I replaced the contactor a couple of months ago so I don't feel the contactor is bad, but maybe it is) So it appears to me as if the thermostat is trying to send a signal to the compressor to kick on. The start capacitor is not bulged, but there seems to be what looks like corrosion all along and around the inner lip of the capacitor. None of the corrosion is touching where the wires are connected.


Hope this information can further help.

 

Since the condenser fan is running, that indicates that the thermostat and wiring to the outside unit are working. It also indicates that the contactor is probably OK. I have heard of a situation where the contactor contacts were burned and it was supplying enough power to operate the fan but not the compressor. However, that situation is pretty rare, and is probably not your problem, especially since you recently replaced the contactor.

Personally, I would suggest that you try replacing the compressor capacitor. It's relatively inexpensive and is a good place to start.

 

Here is a picture of the capacitor that a guy on fleabay is selling. it matches the part numbers on my capacitor. I do not know what you mean by a compressor capacitor, because this is the only capacitor I see on the back of the outside unit. Does this look like the compressor capacitor you are referring too? If so, I will order the capacitor pictured below. I will also include a picture of what my capacitor currently looks like now of my unit.

Here are the information the fleabay seller has on the new capacitor:

This is a BRAND NEW Rheem Ruud Motor Start Capacitor, This capacitor is rated at 270-324 MFD and 330 Volts (VAC). Part # is 43-17075-07. Capacitor is 4 3/8" tall and 2 1/2" in diameter.

 

If you only have one capacitor, and it's that large (~300mfd), then it's likely the capacitor for the compressor. Many systems have 2 or 3 capacitors, since the condenser fan often requires a capacitor. From the picture of the old capacitor, it doesn't look very good. The white "stuff" around the perimeter looks like it has been leaking (leaking electrolyte). If I were you, I would replace the capacitor.

 

Thanks Bob14525!

I figured it was bad too, so I ordered that capacitor I pictured from the fleabay seller, and since he gives free shipping is by way of USPS priority mail, if he can ship out today I may get it by Saturday.

When I changed the contactor 2 months ago, that white and yellow looking stuff in the picture was not on the capacitor, so I assume it began leaking since changing the Contactor.

I will post back when the capacitor arrives and I install the new one.

Two quick question before I go.

1.) After seeing the picture of my capacitor, do you think it still might be the compressor wiring, a loose connection, or burned out terminals?

2.) If the capacitor is bad, I would think that there would not be any juice going through the compressor wiring to the compressor thus enable the terminals to burn out. Would that be correct?

 

It's unlikely that the compressor wiring is burned, especially after seeing the condition of the capacitor. I mentioned that because it is a possibility, however the chances of that being the problem are relatively small. On the off chance that the new capacitor doesn't solve the problem, that's the next place to look.

The capacitor is used to help the compressor start. If the capacitor is bad, the compressor is still getting power, just not enough amperage to let it start properly. For more information on what the start capacitor does, see below.

http://en.wikipedia.org/wiki/Motor_capacitor

 

I suggest you take a look at the RUN capacitor and burnt wires going to the run capacitor. To better assist, can you post the model of your condenser?

A start capacitor is used to give the compressor a "jump start" and is often used on aging compressors. It provides extra torque at start up and then is taken out of the circuit by a potential relay.

The run capacitor should look something like the attached photo.

 

Thanks guys!

Before I go any further I will wait until the Start Capacitor comes arrives and I install it.


firdawgsatx,

I would take a look at what you are calling a Run Capacitor, but the only capacitor I see installed on my unit is the Start Capacitor I have pictured, which is located next to the contactor.

 

The run capacitor is also normally adjacent to the contactor. On some Rheem models the run capacitor is gray plastic and only the top of it is sticking out of the tray and the body of it sticking is down below the tray (as shown in attached photo).

I don't think that will solve your issue.

 

firedawgsatx,

Thanks for the photo. I see where the run capacitor is, as seen in my photos, below. However I see no physical damage to it like I do the start capacitor.

Why would you think the problem might be the run capacitor and not the start capacitor like others in the post are asking me to change first?

 

As explained previously, the start capacitor is only installed to give the compressor a "jump start" and then is taken out of the circuit by a potential relay (the black box shown in your photo). The run capacitor stays in the circuit continuously. The run capacitor is the part of the condenser that fails most frequently. In the case of a dual run capacitor, it serves both the condenser fan motor and the compressor. It is not uncommon to have the portion that runs the compressor fail while the portion that runs the condenser fan remain good. If a person has a voltmeter that measures capacitance the run capacitor can be tested to see if it is still within specs as listed on the label. A change in physical appearance, although sometimes an indicator of a failed run capacitor, does not always appear.


I have changed more of these than I can count with symptoms such as you are having. Without fail, it has corrected the problem. Of course, I have the proper instruments to test the capacitance. I could be wrong, but from your photo it looks to me like either the terminal where the purple wires are connected is burned or the wires are burned. I believe you'll find one of the purple wires goes to the run terminal on the compressor.

I would agree that your start capacitor doesn't look too healthy and it is a great idea to replace it.

 

Here is some more pics.

What do you think from them?

Also, can you give me a ball park figure on what a run capacitor part cost?

 

It is difficult to tell much from the photos. From a different angle, I can't see any definite burnt areas. Depending on where you purchase a run capacitor, it can be anywhere from around $10.00 to $20.00. I purchase all of mine from a local hvac supplier at wholesale prices so I am not sure what they go for retail. The prices on amazon.com are reasonable. If you have a local Grainger's they will have it on the shelf. If you don't have an account with them you can go to their web-site and establish an account by purchasing something cheap and then pick it up at "will call". While there, you can ask for the run capacitor. All you need do is look at the run capacitor label and see what the rating is. It is probably something like 45/5uf 370VAC or 440VAC. Then match a replacement to those numbers. Once you get the replacement just shut off power to the condenser, discharge the run capacitor by using an insulated screwdriver to touch between the terminals and then swap wire for wire. Inspect the wire terminals to make sure they are intact and not burnt. Loose terminals are the primary burnt wires on a condenser.

As I said in an earlier post, the best way to tell if it is the capacitor is to check it with a voltmeter that has the capacitance test feature.

 

I went on and ordered the Run capacitor pictured below, as it matches the numbers on my Run Capacitor unit. The start capacitor will be arriving on Saturday, but since it is this late, this one won't get here until Monday. Funny, but it is from the same seller. It was a 80+5uf 370 volt.

 

80 MFD? I'd sure like to know what the tonnage is on that unit.

 

Rejoining this thread late but earlier you mentioned that you heard a hum and click. Good indication of a defective start cap. I don't service these units for a living but I do many on the side. My policy is when one cap is bad... they both get changed.

 

skaggsje,

My Rheem is a 5 ton unit.

 

PJmax,

I have both the start capacitor and the run capacitor ordered. With the start capacitor coming in on Saturday and the run capacitor coming on Monday I have a couple of questions for you.

Should I wait and install them both at the same time on Monday, or can I install the start capacitor on Saturday and then install the run capacitor on Monday?

Could it do harm to the unit if I install them on separate days?

 

If you don't mind taking it apart twice, I don't see any problem with replacing the capacitors on separate days. If you replace the start cap and the unit runs, you should be okay to use it (if needed) until the run cap comes in. If it still doesn't run after replacing the start cap, then it's likely the run cap that was the problem.

 

Hey guys,

I got this post shown below from a moderator in another forum who this my problem might be my old model compressor.

I certainly hope NOT!

Will you guys tell me what you think about what he said, and hopefully why he might be wrong?



"Condenser fan runs but compressor doesnt...

Both usually run on 240V to avoid the need for a neutral. This rules out any external causes. Your contactor is probably good. There is normally only 1 pair of contacts on it. If your fan has power then the compressor will too. The only chance you have here would be a burnt contact that allows enough current to flow to run the blower, but not enough to get the compressor started. Not common but not unheard of.

Check the compressors start cap (and run cap if it has one). If the end near the terminals is bulging then it "blew" and should be replaced. This is the only repair option you have and they are not expensive. You can gamble with trying it if it looks ok. If it doesn't fix it then you are probably out of luck. Older compressors are known for "throwing a rod" and self destructing inside. They are not servicable items. The compressor has a thermal cutout (inside...of course) and it is supposed to reset but if it fails when it trips, it may not reset. Again, nothing you can do."

 

What he said is possible (anything is possible). However, don't jump to conclusions. I think it's much more likely to be a bad capacitor than it is the compressor itself. Also, many of the newer compressors use the more efficient scroll design. They don't have pistons or connecting rods like the older reciprocating compressors did. Even my 24 year old Bryant system (still running fine without every having any repairs) has a scroll compressor. The two capacitors you ordered will be here soon and you'll know then if it's something simple.

 

Would an 11 year old unit be considered a unit with a old compressor?

Okay guys the new start capacitor came in today so I went on an changed it instead of waiting, because Bob14525 said he said it should not matter if I installed it, or if I waited for the run capacitor to come in on Tuesday. It needed to be changed anyway because as my pictures show it was leaking.

Well it cool as the thermostat went down from 82 to 79, along with the outside lines sweaty and cold, but then the out side unit kicked off completely at 79 when it was set on 76. There was a humming noise coming from it, but nothing was working at all not even the fan. I tried pressing and holding the contactor button, and the fan would come on but then would turn off after releasing the contactor button. So I turned the thermostat off, and waited a few minutes then I turned it back on, and the outside unit kicked on again, but this time I was hearing a clicking noise. When it clicked (about every 10 seconds) you could see the wires coming from the house to the contactor shake when it clicked, alone with the wires coming down to the compressor.

With the fact that it worked and cooled the house for a while before the things mentioned above started happening what could be my problem.

Could my 2 month old contactor have gone bad too?
Could it be that the Run capacitor seems to be bad too?
Could it be in the wiring or something else, as it seems the compressor worked for a while as the thermostat dropped, and the outside line was cold to the touch?

What do you guys think by the information I gave above?

 

It's possible that the contactor has gone bad. Usually a clicking noise is made by the contactor opening/closing (can you see the contactor contacts moving?). However, since you expect to get a new run capacitor on Monday, I would suggest that you don't rush into purchasing a new contactor, and wait and see if the new run cap solves the problem. If it doesn't, then buy a new contactor.

Replacing the run cap is pretty simple, so it's doubtful that you miswired it. Also, as you mentioned, the system did run for awhile, indicating that the system is wired correctly.

 

A little typo there Bob.... he changed just the start cap so far. The run cap has three wires and is a tad more confusing.

Wait until you replace it before going any further. I doubt the contactor is an issue here.

 

Okay PJmax and Bob, I will wait until the run capacitor comes in before doing anything else.

However maybe PJmax or Bob can answer a few questions and help me with something happened that I would like some information about. When I dissembled the wired clip from the one of the two plugs on the start capacitor one of the sides of the clips broke off. When I reinstalled the new start capacitor I used the broke clip end and attached it to the black relay box in my pictures, instead of reattaching that end to the new start capacitor. I did this because the black box relayed appeared to not vibrate when the unit was running as the start capacitor did. With this information guys I have a few questions to ask.

1.) Can I buy a new 8" wire those clips already installed from a store, or do you have to install them yourself by splicing the wire myself?

2.) Does anyone know what gauge wire is used for the capacitors?

3.) What is the name used for those clips on the ends of the wire that connect to the capacitors?

4.) Can they be bought at a hardware store, auto parts store, or they need to be bought at an electrical store?

 

They are called spade connector, you can get them at the hardware store.

 

I don't know the answers to your questions except for #3. The connectors go by various names, however they are often referred to as spade or faston terminals. You should replace the broken terminal, as a loose terminal will cause high resistance and get hot.

 

Thanks skaggsje!!!

Would this fit on the wire from a local auto parts store, as they say 16-14 gauge female spade terminals?

Dorman Conduct-Tite! - Spade Terminals

Solderless
Blue
16-14 Gauge
.250 Wide
Female
20 Per Pack
Color: Blue

 

From my experience that is 14AWG for the connections to the capacitor. To properly replace the wire it should be the same rated wire which is UL 1015/VW-1/105ºC/600V. Wiring rated at those specs is self-extinguishing. I prefer to use high-temp "flag" terminals as well. Most burnt wiring and terminals is caused by loose connections. To find the specs for the wiring in your unit you can find a piece that is the same gauge in the same vicinity so you will be able to find all of the numbers. If you get lucky, you often find some wiring in the unit that is long enough to cut a piece off to make repairs for burned or damaged wires. These terminals are usually 1/4".

 

Where can I get these spade terminals you have pictured?

 

Here is where I get them: Supco T Series Female Quick Disconnect, Non Insulated, High Temperature: Disconnect Terminals: Amazon.com: Industrial & Scientific

Of course, you would never use that many. $4.47 is a good price, especially if you have Amazon Prime. You can do what a lot of people do; go to one of the big box stores or hvac supply locations where the pros go early in the morning to buy supplies. Then ask one of the guys if they could hook you up with a couple of terminals. I am always giving people wires and terminals to help them out.

As far as the wire, hopefully you have enough of the original wire to strip back a little and crimp on a new terminal.

 

Can you just use a pliers or do I need to buy a griper tool to get the connector to hold tight on the wire?

If so, can you direct me to the brand you own, and where I can buy one?

 

Finding a tool that crimps flag terminals properly is a great challenge. I use two different crimpers; a ratcheting style and the one shown in the attached photo. I wouldn't go out and purchase a new crimper just to do one or two flag terminals. I see a lot of hvac techs use the Klein crimpers with red handles to crimp the flags. Basically, a crimper that has the crimping part towards the very end of the jaws will work. Just make sure to give the wire a couple of tugs to make secure the crimp is secure.

 

Another option, if you have a soldering iron, is to crimp the terminal onto the wire as best you can with a pair of pliers, then solder the terminal to the wire.

 

That is a great suggestion and makes for a secure connection. Crimps are used in the field because they are fast to install.

 

Thanks guys for your suggestions, but I would have to buy a soldering gun, so just as soon buy the crimper.

Can you just buy a 10" 14AWG wire with the (UL 1015/VW-1/105ºC/600V rated) female spade terminals already installed onto the wire?

 

Okay guys I am at a stand still and very confused, disappointed and frustrated. I got my run capacitor in and installed it after installing the start capacitor earlier in the week. I am having the same problem and nothing has changed. The fan will kick on the outside unit when the thermostat is lowered without the compressor kicking on. When this happens there is a buss/click sound with vibrations in the two wires coming from inside the house to one side of the contactor, and with vibrations of the wires from the other side of the contactor to the box on the compressor. I touched the wires when this happens coming down to the compress box installed on the compressor, and I feel current going though them. So it appears to me that the thermostat is sending a message with current to the contactor, with the contactor working to send current to the box on the compressor. However the compressor is not kicking on.

Below I have included two pictures with the wires circled (#1) from inside the home to one side of the contactor, and circle (#2) the wires from the other side of the contactor to the box installed on my compressor.

I hope this information can help you to help me find a solution to my problem.

Thanks for all your help!