Now A/C Problem

[rideandslide]

Hello All
Just at the end of a great 3 day trip to Charleston SC. we have a big time a/c problem.
Came home from day tripping and found the roof/top Dou Therm ac coils had frozen over, turned it off and since it was going to be a cool night we just opened up the window and enjoyed the night.
Next morning they had defrosted and we turned the unit back on and left for more touristing and returned to a nice cool TT with no icing. The unit was not running when we returned so i bumped the thermostate down a bit to see if it came on, and it did, so i returned it to the origininal position and the unit shut dowm, great, i thought no proplems, then the witfe lowers it again and the lights flicker and a clicking or crackling sound from the ceiling area, but it starts and blowing nice cold air. We go outside to gather with friends and 10 or so minites i return for a beer and the unit is just hummimg ( compressor sound ) no fan running, so i tried to turn it off from the thermostat and nothing, no response, had to turn if off from the breaker. We are back home and so far is has not healed itself, turn the breaker back on and the hum/compressor come on, no matter what is at the thermostst.
Any Ideas ????
Jim
2000 Keystone Sringdale 25rkls

[lx22]

Sounds like your blower motor went out. Rather than try and replace parts i would suggest a new unit. If your signature is correct the unit is 14 years old. You can find a new unit for about 500.00 plus installation. That is my suggestion but maybe i am wrong and its something simple.
Good luck

[jesilvas]

There are different hums: compressor humming and running freely, compressor locked and trying to pump, fan motor locked and trying to turn. So you need to diagnose what is humming.
And even with t-stat in off position, the hum is there? What t-stat do you have?

[rideandslide]

Basic Dou Therm analog thermostat.

[wa8yxm]

There is argument over what causes icing, Turns out there are 3 possible causes.

1: Low on coolant, This actually happened to me one time, next time the A/C was totaled and needed to be replaced, Long story but it was a SERIOUS coolant leak But first it froze, since it was running at the time.

2: Filters clogged, fan on low or both Though clogged filters on my RV tends to get a different set of symptons (Niagra Falls when the blower shuts off, dripping till then)

3: Frost sensor missing or improperly positioned.. ONLY on some models.

If yours is a Carrier Air V.. Have spare blower,, Will be in Fair Play SC next two weeks. (Currently in Pendelton but not for long).

[def]

Check motor start capicators.

[jesilvas]

Wa8 is right on icing causes.

But it's not for sure one thing. It can be icing AND a bad fan motor now.

[rideandslide]

Update-- Tried it this morning and fan and A/C come on and work,but when turned off ,fan and air stop, but still a constant humming till breaker turned off.
Must say unit is fithy with dust buildup on everything, can't believe i did not go in there and clean it since we purchased it !!!!!

[jesilvas]

If fan stops but compressor keeps running, the relay in the control box is probably stuck closed and you need a new control board.

[rideandslide]

Well-- i"m fairly sure it's the compressor relay. Is there a part number on the conrol board itself ? I can remove that from inside the trailer. Donetic/Dou Therm says ignore any unit model numbers except the one under the cowling on the roof. Being 260# and a 14 year old trailer, i'm not crazy about getting on the roof.

Jim

[jesilvas]

Look on the underside of the A/C, from the inside. Pull the filter, look up, there is a sticker. That has the model and product number, and you need both. They will probably make you upgrade to the new digital t-stat and matching control board. I think we sell them for $100.

And as far as getting on the roof, unless it's rotted, you're fine.

[rideandslide]

Was able to get down to the control board and get the part number. $54 from Anyrvparts. Guess it worth a shot.

Is there suppose to be a air filter in there ? None visible, just a filthy exchanger.

Jim

[jesilvas]

The air filter is a foam piece on the plastic grille, and that's it.
You need to clean those.

[rideandslide]

I don't see any sign of a filter in there, will look more carefully in the morning. Where is it located?