Originally Posted by ReMetau
We have a 3 year old Dometic Marine
Air 16000 BTU AC. We have been having a problem where the coils are freezing up which eventually leads to the system freezing up to where it doesn't even cycle air.
We had an HVAC guy look at it about 3 weeks and he checked the pressure and for leaks and didn't find any problems. He charged it up anyway.
The unit works fine at night and all night long until later in the morning when the outside temperature begins to climb. We then have to reverse cycle it to heat until the unit defrosts and then we can start again. It seems that the head unit isn't kicking on the defrost cycle during the day but it does in the evening and night. We are thinking it is a bad head unit.
Any suggestions besides calling out the HVAC guy again?
He didn't fix it the first time? Just added refrigerant?
Restricted air flow is one cause of coils icing up but the HVAC technician should have checked that. An undersized AC or too much heat gain will do the same thing. If you have a lot of sunlight and heat coming in through the windows you could have this problem. Tinting your windows might help. Get the high tech heat reflecting tint installed.
Your thought that the defrost cycle works at night but not in the daytime doesn't make much sense. The AC doesn't know if it's day or night.
I say call the guy and tell him that he didn't fix the problem.
BTW: If there were no leaks but the refrigerant was low, it could have leaked into the cooling water
in the heat exchanger
. If the tech finds it low on refrigerant again (assuming it was low the first time), this may be your problem. Ask him about it. I had that problem and it's unrepairable. I had to replace the unit.