I have a Trane XL 1200 A/C. Indoor temp last night got to 82; saw outside fan was not turning although air (not cold) was blowing out of the register. Circuit breakers were not tripped. After consulting online resources, including this site, I turned off the thermostat, turned off the breakers and removed the pullout at the outside unit. Looked fine to me. Waited about 2 hours, put pullout back in, turned the breakers back on, turned the thermostat back on, and it worked fine. After about two hours, I heard a nasty groan and saw the outside fan stopped working. Turned off the thermostat overnight, turned on this morning and it worked fine. Came home for lunch and outside fan wasn't turning. Turned off thermostat, waited 30 minutes, turned on thermostat and it worked. Came back to work, wife just called and said outside fan wasnt working, inside temp 83. Thermostat is now off. I would greatly appreciate any guidance. Thanks in advance.

 

Sounds like you have a run capacitor problem or a bad fan motor. If it is a run capacitor problem it can be identified by the fact you can push the fan blade with a stick and it will continue to run until the thermostat shuts off 24v to the contactor. A bad run capacitor can sometimes (but not always) be identified by a bulging top or leaking fluid. Sometimes you will find a burnt wire or terminal going to the run capacitor and cause issues. I would suggest you start by turning power off at the disconnect, removing the access panel and look at the run capacitor and associated wiring.

A condenser fan could also be a possibility since you heard a "groan" at one point. Many fan motors have thermal protection built-in and will shut off when overheated. When it cool offs off enough it will reset the thermal protector and will resume operation until it heats up again only to repeat the cycle.

XL1200 is a trade name. To better assist you, can you post the model number of the condenser? It should be located on a label on the left rear corner of the condenser cabinet.

 

Thanks for your reply. Those were my thoughts too. My understanding is that if its a capacitor problem, it wouldnt start at all - a capacitor supplies the initial burst needed to get the fan running. Is this correct? If so, doesnt the fact that the fan starts (albeit after shutting the unit down for some time) mean the capacitor is OK?

 

Thanks. Model number YCY048F1H0AD. I opened the front panel last night and didnt notice the capacitor bulging, but it was dark and I wasnt specifically looking for it.

 

No, the fact that it starts up again could mean the capacitor is weak. In the field we use a multimeter with a capacitance checker to see if the microfarads are within specs as listed on the label. If it is out of specs we replace the capacitor. Most DIYers replace the capacitor because it is the cheapest and usually the problem.

 

You had me at microfarads. Do you recommend replacing the capacitor to see if that does the job?

 

I suggest you first try the "stick" test and look for any obvious signs of bulging. Most of the time replacing the capacitor will correct the problem. But as I said, it could be the fan motor as well shutting down on high temperature. If you decide to replace the capacitor, make sure you replace it with one that matches specs on the label.

 

I couldn't get the fan to run with the stick test and see no obvious signs of bulging. What I believe to be the capacitor is a black cylinder marked 330vac 50/60 hz. The fan tried to start on its own accord when I tried the stick test and I heard the noise again, it's more of a buzzing than a groan, sorry for the confusion.

 

The run capacitor is usually aluminum color. It is probably a dual run capacitor and will have three sets of terminals and will have several wires attached to them. It will usually have the terminals marked C, Herm and Fan. It should look similar to the photo of the bulged capacitor I posted earlier. It could be round or oval.

 

Ok. After some research and your reply, I think I was looking at the start capacitor. There are two run capacitors, a small one for inside and a larger one for outside. They don't have any obvious markings, but a paper in a laminated folder on the access panel says the outside run capacitor is 15 MFD 370v oval without resistor. Does that sound right? Again, thanks for your responses and patience.

 

That would be one for the compressor and one for the condensor fan.
The inside blower (air handler) has it's own capacitor.

15mfd sounds about right.

 

Thanks. I see no obvious signs of bulging and firedawg's stick test didn't work, does that rule out the capacitor as the problem?

 

No, as stated earlier, bulging does not always appear. If the fan doesn't start up with the stick test the capacitor could be too weak. You need a multimeter with capacitance checker to test your capacitor.
Otherwise, it is just a guess

 

I replaced the dual capacitor (45/7.5 mfd 440v). The hard part was finding a place that would sell me one. AC started right up and died 30 minutes later. Is it possible I erred in the installation, or is it something else, perhaps the motor?

 

As long as you swapped wire for wire from old to new capacitor it should have been installed correctly.
After the motor shuts off after 30 minutes, does the compressor continue to run? Does the fan motor start up again after awhile? It is not good to run the compressor without the fan running to help cool it off. A dirty condenser coil is one of many reasons the fan motor will overheat and shutdown by tripping built-in thermal protection.

 

I swapped wire for wire. It was actually pretty straightforward. I am not certain how to tell if the compressor is still running, but I can tell you that after the fan cuts off I hear sounds from within the outside unit (all I have is an outside unit; no internal air handler. I googled my model number and saw it referred to as a "rooftop unit") and that (warm) air continues to come through the vents inside. I turn off the thermostat when the fan cuts off. I doubt the coils are dirty, we had freon added in June and they cleaned the coils then.

 

Once the fan shuts down the compressor will usually shutdown on thermal overload. It is designed this way to protect it. There are a few things you can do through observation to check the fan motor. To properly evaluate the fan motor requires a clamp meter to see how many amps it is drawing when running. About all you can do without the required meter is to shutdown power to the unit, get access to the fan motor and spin it to see if it spins freely, if there is any "play" in it or makes any noise such as bad bearings. The fan motor can also be ohmed out to test the windings but that really is not a definitive test on a cold motor.

 

Thanks again for the response. You suggest the following: "get access to the fan motor and spin it to see if it spins freely, if there is any "play" in it or makes any noise such as bad bearings." Are you saying I spin the fan motor or the fan? If it doesnt spin freely, can you use 3 in 1 oil on the spindle?

 

I meant rotate the fan by hand (power shut off, of course). A bad motor will sometimes spin freely so that is not always definitive if it does spin freely. Most condenser fan motors nowadays are sealed and don't have oil ports. Being a Trane, you may find oil ports on the motor. If so, carefully pull out the plastic plugs and drip oil into the holes until full. Then let the motor sit awhile with the holes facing up and once empty add more oil. Repeat this process a few times. This process is wetting a felt surrounding the shaft bushing and it takes awhile before the felt will become wet enough so the oil will seep into the bushing. 3-In-1 works pretty well. It is worth a try, anyway.

 

I removed the motor last night; no oil ports visible. I suppose my next step is to get a new motor.

 

Of course, only you can make that determination. Diagnosing over the internet is difficult and without physically being there and doing the basic observations and testing amp draw, ohming out the windings and etc., it is impossible to determine exactly what is going on with it. Based on your description of what is happening, it does point to a bad motor. You could attempt to get some oil to run down the shaft and into the motor. You might get lucky and get it to run for awhile to buy some time, but who knows how long. If you decide to buy another motor make sure you get one with the same specs such as HP, RPMs, frame etc.

 

Electric motor shop did not stock a replacement, but they examined the motor and said the bearings are likely shot (or it could be the shaft). They are going to open it up and see. If its the bearings, they will replace, if its the shaft, its apparently not worth fixing. Thanks very much for your willingness to deal with my repeated questions.

 

No problem, with the little bit of long-distance assistance I was able to provide. Please post back with the results of the motor repair or replacement as that will help others experiencing similar issues in the future.

 

It was the bearings. $75 for the repair and 30 minutes for me to install. That was Friday evening, it's been running great since. Thanks again for your help.

 

Great news! Thanks for the update.

 

Almost exactly one year ago, this forum helped me through a problem with my A/C (see thread below).

Last night I heard an ugly groan/rumble from the outside unit (there is no internal air handler, the entire system except the ducts is outside). The large fan attached to the motor I had fixed last year (I think this is the compressor fan) spins freely and at normal speed. Last year, when the compressor fan stopped working, I could feel warm air coming out of the vents. Now, although the compressor fan is working, I feel no air coming out of the vents.

I turned off the A/C all night and turned it back on this morning, the compressor fan worked fine but I heard what sounds like another motor, lower and to the left of the compressor motor, churning slowly and angrily. I turned it off again. Is this a blower motor?

Thanks in advance for any advice.

 

Yes, it sounds like you're experiencing a problem with your blower motor or the blower assembly (usually referred to as a "squirrel cage" because of the appearance). If you heard a groan/rumble noise, then it's possible that you have a bearing issue on either the blower motor or the squirrel cage assembly. The only way to tell is to remove the blower assembly or remove the belt (if belt drive) and see if the blower motor or squirrel cage rotate freely and without noise.

 

Yep, squirrel cage. Nobody will sell one to me unless I have a GC license, at least if I want one within a reasonable time. Thanks for the response.