Coleman Mach blowing hot

[pstroke]

I have been leaving the thermostat around 80 degrees while we are not using our 2018 377RLBH. The unit blows cold and keeps the RV at a constant temperature. It is kept inside an enclosed and insulated metal building out of the hot Texas sun.

The problem comes in when after a few days I go back out to the RV and the unit is blowing, the compressor is not running and it is 95 degrees inside. Once I turn it off and back on, the compressor kicks on and the unit starts to blow cold air (20 degree differential).

I am guessing I either have a voltage problem when the compressor tries to start back up or the start capacitor may need replacement.

We are going on a trip next week and don;t have time to leave at the dealer for them to figure it out. I am going to monitor on our trip and see if the problem duplicates itself.

Anyone with suggestions on what to check, please chime in. Thanks.

[Grumpy]

That sounds like a Thermostat issue to me.

[wags999]

Could also be icing up. Is your fan on high? If it's 95 outside and humid, you want to use the high setting so your moving more air, to remove excess moisture. Another thing to check.


Good Luck and have a safe trip.

[Mopar_Earl]

Make sure the temp sensor probe is in the evap. Sometimes they forget to install it or it falls out.

I would also look at the thermostat.


Earl

[pstroke]

Fan is on hi. I will see if I can locate the temp sensor.


I pulled the t-stat off the wall, check all of the connections and put it back on the wall. As far as operation, it appears to be working properly. Not sure what I can do to test it.


It has not been freezing over. As soon as I notice it blowing hot, I turn the breaker off and back on and the compressor starts right up and starts blowing cold pretty quickly.


I have done the vent mod and that really helped the air flow in the living area but looks like it cut down on the airflow into the middle BR, which makes sense. The airflow in the MBR is good with the front unit on as well.

[Rock]

When u r looking at temp sensor make sure the piece that separates the blower fan did not come loose.
Rock

[TxLoser]

I'll be following this. I always run the bedroom AC in mine at night for the sound and cold. Woke up the last morning to minimal flow, and no cold air. Just fan basically. Didn't have time to troubleshoot as we were leaving anyway. I'm just hoping it's a one off event.

[pstroke]

I pulled the cowling off the unit on the roof. All sensors seemed to be in the proper location including the freeze sensor stuck into the fans on the evaporator coil. The cooling fan motor and the blower motor both seemed extremely hot to the touch. I have to assume this is normal in the heat of the summer.



On the return air side of the unit, the factory did a pretty sloppy job of sealing the unit to the duct on the inside. I took the same aluminum duct tape that I used on the vent mod and sealed the gap the best I could. Otherwise, put everything back the way I found.


So today, the current OAT is 95 with 42% RH. I took my laser temperature sensor and shot some temps inside my shop where I keep the RV. Concrete floor was 85, halfway up the side wall it was about 90, at the top of the sidewall it was 101 and the roof of the shop was 124! Yes, 124! No wonder the units are running all day to keep the inside at 75. I probably need to turn the HVAC off when we are not using and only cool down when we are loading up for a trip. This will make the residential refrigerator work harder though. I could also keep the doors to the shop open to help exhaust the heat from above the RV.


We took a trip to Lake Texoma last month and the first day we were there the outside temp was over 100 with high humidity. Could not get the inside temperature below 85 until the sun went down. Got it in the 70's overnight inside and held through the next day although the high temp was only in the mid 90's.



Hopefully our trip to Austin this week will be uneventful. Hate to have a brand new RV that the AC does not work right and have down time while getting repaired.

[TxLoser]

How'd the AC do on that Austin trip?

[pstroke]

It worked perfectly.


I have come to the conclusion that the HVAC unit is overheating while it is my shop. With the 100+ degree temperatures outside it has been very hot inside the shop. With the doors closed or partially opened it has been over 125 at the top of the shop. I have to believe with the limited air circulation and excessive temperatures that the compressor or fan was overheating and shutting down to protect the equipment. Once it was outside with plenty of air circulation it worked great.


I was trying to keep the RV at about 80 in order to not make the refrigerator work too hard. I have shut the AC down and will just cool the coach down when needed.

[TxLoser]

Glad to hear it worked well for you. Thanks posting.