AC problem

[Possum]

By AC unit was merrily churning out very cold air and it suddenly stopped producing cold air but the system fan kept blowing air around.

The compressor was doing its thing cycling on and off and it suddenly just quit. Strange thing that it went from lots of cold air to none in a nanosecond.

Anyone have any ideas as to what is the cause. The unit is installed on a 1977 C Class Diplomat made by Lethbridge Industries in Lethbridge Alberta, Canada.

[RJay]

What is the AC voltage coming into the coach?

[mrtinker]

Do you know how to use a multimeter? If yes, you can fix it with a bit of guidance as to what to look for.

If not, then you need to know how to post pictures on this forum and I'll bet you can still fix it as stated above!

First I'd recommend taking a look at the complete system... you know... power comming in, fuses, then look around for the other simple things, corrosion, loose connections, rats eating through wires/insulation.

This is also the time of year for power problems with the storms and all... blown up capacitors are fairly common.

If it turns out there's a refrigerant problem then you may have to borrow or buy some specific tools though.

Good luck. Check with the obvious stuff first and if nothing pans out take a few pic's and get them on here. We'll help you to get er' fixed up in no time!

[RV Wizard]

Could by chance the unit be a heat pump? If so and the reversing valve solenoid went out it can change the temperature very quickly as you describe. Otherwise, you may have lost the valves in the compressor for it to change temperature so quickly. Please give us as much information as possible for the best in assistance.

[Possum]

I will check (now that I have been asked to) the input voltage at the point of plugin. I could also try running it on my 3500/3000 amp generator to see if low voltage is a problem.

I've checked all the fuses and breakers and all are OK and in operation and the fan in the unit is still running, just not the compressor motor. I have to finish the fridge installation today as the weather will be cool and overcast and I can work without the air-conditioner working today.

I will post pictures of whatever I find out when I get the covers off, so to speak.

Thanks for the help offers rendered so far.

[Clay L]

A common cause for the compressor shutting shut down and the fan continuing to run is the evaporator coils freezing up.

That can happen in high humidity areas especially if the fan is on low speed.

It can also be caused when the fins on the coils get so clogged with stuff like pet hair and dust that the airflow is greatly reduced.

On mine last year I found that from the top to 2/3 of the way down mine had 7 years accumulation and no air was getting through that area. The freeze sensor sensor was shutting the compressor off.

I had to go up top, remove the shroud and air plenum so I could get to the coils to clean them. I used a brush and brushed in line with the fins so they didn't get bent.