A/C Woes...read and comment please

[Papicamper]

I will just present details. Would like suggestions/comments. Thanks.
Spent week recently without main A/C (Dometic A/C heat pump 15 K) unit in living area. Almost no cooling whatsoever. Temps in mid 80s so not real painful. Bedroom unit worked great. Thank goodness.
Took rig to repair shop. They found 72 deg outside temp gave 42 deg at vents. Cannot verify their work. Took rig home.
I made SEVERAL tests and lowest I could get vent temp to be was 60-61 with approximately same OAT (mid 70s) over 30 minutes. This is with 72-74 outside and 60 minimum inside at vents - only about 10-11 deg diff. Bedroom unit gave 20 deg differential under same conditions in 10 minutes.
I believe I have a problem. Again, all week on trip could get no cooling...no weird sounds, vibrations. Pulled cover, inspected for obvious...nothing found. Can hear compressor cycling. Thermostat is same one used for bedroom unit. Am I being given a line of bologna? Unit goes through the motions...just doesn't cool. Less than 2 years old. Got an email out to Dometic but wanted views. Thanks!

[boggesss]

I am having the same problems with my new 2014 Salem. The main A/C unit doesn't cool out of vents. The dealer has had in and out of there shop multiple times with no success. They say its not in A/C unit. They are not talking about leaks in ducting in ceiling. Going to tear out some ceiling panels next visit. They found it by removing some lights in ceiling and feeling cold air come out holes. Hope this helps

[Papicamper]

Thanks for your hint but I have plenty of air coming out of the vents...it's just not cold. Spoke with Dometic and they said there should be 16 to 20 degree difference in return vent and nearest outlet vent. Bedroom unit (13K Penguin) "Rocks" with 20 degrees after only a few minutes. RV going to Camping World on Jan 10th and will let you know. FWIW, I have tried twice, again, to measure temp difference and only max out at about 10 degrees difference and that doesn't last very long...then it goes back to between about 5 and 8 degrees difference...not cool...pun intended!

[ebemis]

For whatever it is worth..I have had similar experiences from time to time and have gotten the AC to work again by removing power to the system temporarily and then turning it back on once the fuse/breaker is back in service.....Not sure if thermostat's are possibly sporting an intermittent fault or what. In any case you might try something similar, find the fuse or breaker that supplies power to your AC system, remove/open them for a few minutes, install/close them back in and then power the system on again to see if the compressor kicks in and delivers cold air.

[Witch Doctor]

Originally Posted by Papicamper

Thanks for your hint but I have plenty of air coming out of the vents...it's just not cold. Spoke with Dometic and they said there should be 16 to 20 degree difference in return vent and nearest outlet vent. Bedroom unit (13K Penguin) "Rocks" with 20 degrees after only a few minutes. RV going to Camping World on Jan 10th and will let you know. FWIW, I have tried twice, again, to measure temp difference and only max out at about 10 degrees difference and that doesn't last very long...then it goes back to between about 5 and 8 degrees difference...not cool...pun intended!

It sounds like a cycle problem and it is either the compressor is short cycling or you are low on freon. Your compressor should not shut off unless it is tripping your overload or your high and low side valves are allowing feed back. If you are hearing the compressor shutting off and back on again with the system in auto and the indoor fan staying on your low on freon. They do not check that being they would have to add schrader valves to both the high and low side to check. These unit's do not come with access valves. You can not check the charge without them. These units hold like 2 and 1/2 lbs of freon only so being even a 1/4 pound low will cause that and start the icing. On the name plate it will give you the exact lbs. needed. Plus the FLA when running you need a AMPROBE for that. There is no duct work in the ceiling just tunnels. Also pull your plate inside (R/A) and make sure that the 2 sides supply and return are sealed, so you don't short cycle and bleed cold air (supply) to the return side. Sometimes there is a gap in between.

[Papicamper]

As far as power cycling...I agree but remember, it was at least 3 hours without power getting to our campsite where the problem was discovered. Also I can fix most anything but I have always steered clear of refrigeration...no tools and limited knowledge. I'm going to see what CW has to say. I was suspicious of the low on Freon thing but have never had any icing occur. You SURE there's no way to top off Freon? That seems very weird...if that's so then Dometic will have another carcass on their hands! Compressor does cycle on/off and physically sounds very normal. Could measure (have amprobe) but just think I'll have [another] drink and let CW figure it out. If they tell me "It's working" I will warm up the cabin and see for myself before driving it home. Stay tuned...(I'm in broadcasting...sorry). BTW, maybe it'll take a couple drinks!

[OldCoot]

Our compressor cycles on and off and cools just fine when the thermostat is set to Auto.