Out of 6,201 members of this forum there should be a refrigeration person.

The A/C on my TT works fine at start up and cools off nicely, but then the compressor shuts off and stays of for too long a time letting the air get quite warm. When it does finally come back on it doesn't stay on long enough to cool things enough then is off again.

Is my thermostat going bad? Or is the compressor going bad? Something else? Is there a way (there must be) to check these items? At temps above 100[sup]o[/sup] it is badly needed.

TIA for any and all help.

Stan

 

It could be a lot of things:<br>1) First, 100* ambient is (probably) going to be outside the design parameters of the trailer and will cause the cooling capacity of the a/c unit to derate as it is much harder to reject heat into that hot of air.<br>2) Try leaving the fan running. It will keep the air circulating and keep a more even temperature inside.<br>3) Is the condenser coil clean. With it that hot outside and if the coil is dirty you could be causing the unit to trip on an internal overload. Usually if that happens it takes quite a while for the overload to reset but that could be happening.<br>4) If you have a volt meter you can check the t-stat for proper operation. You can either unwire the stat completely and check for continuity by running the setpoint lever up and down or leave it wired to the system and check for voltage on the wire heading to the compressor starter. Haven't actually looked at my trailer unit but on a home unit the signal to the contactor is usually on a yellow wire (could be red) Check for 24volts ac going while the compressor is running. It should drop to zero when the compressor shuts off. Then watch for the relay in the stat to make and see if the compressor starts right then.<br>5) Get a thermometer with a large display that can be read from several feet away. Stick it right above the t-stat and move as far away from it as possible. Watch it through several cycles. Most t-stats have a dead band of around 2 degrees. So, with the setoint at 72 the compressor should shut off when the temp gets to around 70 and turn back on around 74. Remember, the thermometer you will be using won't be very precise so a degree either way isn't a big deal. But, if you have a large swing (6 degrees or more) you might have a bad stat.<br><br>That should give you a starting place and a couple of things to check. Also, did you look for the sensing bulb like Gary suggested? If it gets loose or bent away from the proper location it can cause improper unit control. I think though that type of element is only used with unit mounted temperature controls. If you have a wall mounted thermostat the temperature control is based there. good luck

 

Sounds like either a bad expansion valve or moisture is in with the refridgerant.