A/C diagnosing help

[psikora]

I haven't gone up and removed the cover for model specific info, and the paperwork I have only refers to the unit as 15,000 BTUs, but I was hoping to do a little diagnosis g before I bring the RV in for service. So I'm going to the well again.

It's an Atwood model, operates off of a Domestic switch, and doesn't blow cold.

Any thoughts?

TIA,
phil

[cruizerEd]

I'm not going to go over all the safety stuff but be sure to understand that you can get killed by the power or seriously injured by the moving parts of an A/C.

By "doesn't blow cold" I assume that the blower is coming on and you have good air movement inside the coach.

That means that the unit is probably getting the proper signal to cool and that the blower is running.

Is the condenser fan running. The condenser fan is the one on the outside and is typically fairly noisy. If is not running that is your problem. The easiest thing to do is to replace the starting capacitor for the condenser fan it is cheap and easy to replace and is probably your problem. Typically a bad capacitor will have very apparent stains around the overpressure vent. If it does not have a vent it may look "inflated" or the top maybe bloated or loose.

If the capacitors aren't bad you will have to see if the fan can turn freely, is getting power, and that it is not burnt out by checking the resistance. If it isn't getting power then the leads or a relay is bad. If it doesn't turn freely or is burnt out you need a new fan motor.


If the condenser fan is running the easiest shortcut is to replace the compressor start/run capacitor and see if that is the problem. You can inspect them for damage or just replace them even if they look good.

If you want to to make sure the capacitor is bad first you'll have to check the voltages and current on the compressor to see if it is running. Alternatively you can try to see if its running by listening to it to see if it sounds like it is running or if it is just vibrating or only running a very short time. Don't do this often or long because you can burn out the compressor. You can disconnect the condenser fan while doing this to make it safer and easier to hear/touch the compressor.

If you think the compressor is running then your freon has leaked out or the compressor has some sort of internal damage. I'm not sure but I suspect that either of these implies you need a new A/C.

If you do get it running again now is a good time to clean up the evaporator and condenser coils and the A/C chassis itself. Cleanup whatever handles the condensation water drainage. Check the roof to A/C seal. Put some UV protection on the cover. Things like that.