AC Issues

[africaroots]

Its hot here and I'm having problems with my AC!

It's a 71 Excella, recently purchased. A few weeks ago, the AC worked fine but now when I turn it on, it cools for about 30-60 seconds, starts to slow down, makes a loud pop sound (like the breaker or something) and then blows warm air.

I am in an RV Park so I am connected to a 50 AMP source; I have a brand new battery (a car battery - 500 cranking amps); my Airstream does have a Univolt converter I believe (fuse looks ok to me); not running any other major appliances.

Any ideas? Does the AC run off of the battery at all or just the main power source?

[HowieE]

The AC runs on 110 volts and has no connection to any of the 12 volt systems.

First thing to do is check the voltage the campground is supplying. If below 105 that may be the problem. Low voltage will cause the unit to draw added current and that can cause the unit to shut down for self protection.

Secondly if it is very hot outside and the box is hot that also will cause a heavy load on the unit and may give the same result.

[Jammer]

What you describe is probably caused by a lack of airflow over the condenser coils. Usually this is because they are blocked by leaves or other debris; more rarely, it's because the fan is damaged. The problem can be corrected by climbing on the roof of your trailer, removing the air conditioner shroud, and cleaning up the mess or replacing the fan blades as the case may be.

Be careful to be sure power is disconnected and locked out, and don't fall. There are a number of threads on airforums explaining how to get up on the roof without damaging your trailer or falling off.

[africaroots]

OK thanks... I am going to go check it now. Will report back in a bit

[africaroots]

OK I just cleaned out the entire AC unit (removed the shroud, coils etc. and vacuumed out the debris - there was a lot). It lasted a bit longer before it popped and quit blowing out cold air. It does sound like it is having a hard time.

FYI - we've been on 2 campgrounds - 1 was a KOA and now a local RV park and both have plenty of wattage (so I am told). Everyone else around me is ok with their trailers (no Airstreams of course).

Any other ideas??

[africaroots]

Update: I went on the roof while we turned it on and for about 30 seconds it ran but the fan did not move at all. What can I do to replace the fan or get it working?

[HowieE]

OK you have defined the problem. NO fan high head pressure and the compressor shuts off on it's thermal overload.

Try moving the fan by hand a bit and then turn it on. If the fan runs you may get away with it for a while. If the fan does not run the motor may be shot and replacement is in order. That can be done without losing the charge in the unit so it is worth considering if yo can find someone to do it.

[68 TWind]

Could be a relay or capacitor.

[Jammer]

I'm a little puzzled because most RV air conditioners have a single fan motor that drives both the interior and exterior fans, so they both fail at once. But your interior fan is working.

Maybe the collar for the fan blades is broken so the shaft turns but the blades don't, or maybe the motor shaft is broken. If you try to turn the blades by hand (with the power off and locked out) and push and pull gently on them you should be able to tell.

If the exterior fan has its own motor then chances are that the bearings are seized up. You can find out for sure by turning it by hand (power off and locked out), if it turns hard or not at all then that's what you're dealing with. Sometimes you can get it to work for a little while by turning it around by hand a few dozen times to free up the bearings but ultimately you'll have to replace the motor.

If the motor turns OK by hand but doesn't run under power then chances are that a wire was cut or pulled loose, either by a small animal or as a result of cleaning out the debris. Otherwise it might be a bad fan motor capacitor. They usually don't fail unless the case has rusted through and the oil has started to leak out. There's an outside chance that the motor has failed electrically but that's pretty rare.

[africaroots]

Looks like HowieE was right on this one...

I turned on AC, got on the roof and gave the fan a spin (with a piece of wood of course) and it worked. I'm assuming I will have this problem until I replace or repair the motor. Feel free to chime in on recommendations on this part. It is the original motor/AC unit as far as I can tell.

FYI for other people reading this post; my fan blade was very easy to turn by hand (stick) with the power off so HowieE diagnosed it wasn't necessarily the fan. My unit has sat a lot.

[africaroots]

Looks like HowieE was right on this one...

I turned on AC, got on the roof and gave the fan a spin (with a piece of wood of course) and it worked. I'm assuming I will have this problem until I replace or repair the motor. Feel free to chime in on recommendations on this part. It is the original motor/AC unit as far as I can tell.

FYI for other people reading this post; my fan blade was very easy to turn by hand (stick) with the power off so HowieE diagnosed it wasn't necessarily the fan. My unit has been stored quite a long time.

[Jammer]

If the fan motor has a capacitor you may be able to get away with just replacing that.

[68 TWind]

If it runs with you spinning the blade it is most likely the start capacitor. Exactly which model AC do you have?

[africaroots]

Originally Posted by Jammer

If the fan motor has a capacitor you may be able to get away with just replacing that.

Originally Posted by 68 TWind

If it runs with you spinning the blade it is most likely the start capacitor. Exactly which model AC do you have?

I think an Armstrong (Serial number 976160, model TRC2-12, CW17).

[tesstoaster]

The condenser motor probably does not have a start capacitor, but will have a run capacitor. It really sounds like your problem is the run capacitor for the condenser motor. I just successfully refurbished my Armstrong TR21-12 by replacing the condenser motor, as well as the run and start capacitors. The start capacitor generally is for the compressor. In my case the run capacitor was a three way, a 30/7.5/7.5 MFD capacitor. The new condenser motor required a 10 MFD, so I replaced the original 30/7.5/7.5 MFD capacitor with a 30/10 MFD capacitor and then ran a separate 7.5 MFD to the blower. The Armstrong runs great now and am glad I did not relegate the Armstrong to the dump.

I think the investment of $30-$40 to get new run capacitors is a worthy investment, so that is where I would start. Oiling the condenser motor bearings/sleeve may be required too in your case. Good luck...