Domestic ac freeze up

dougrainer wrote:

Sorry, IF the Freeze sensor is installed correctly, NOTHING will cause a Freeze up. I WORK on RV's for a living and have and still do for 38 years. I see more Dometic AC's in 3 months in the summer than all combined on these forums. I also NEVER see a Low charged unit. IF the unit is low charged it is because of a leak and after about 30 days the 410 or 22 will be GONE. They only hold 16 ozs of coolant. LOW charge from Dometic is almost non existant. I REPEAT my question, HOW do/did you determine they were LOW charged or had a leak? Google????? Well, The internet is NEVER wrong or has Factually inaccurate information. Doug

So then Dometic or our RV dealer installed it incorrectly. Because they replaced the unit 2x under warranty! Once in Sept 2015 and once in June 2017.

And if you do this professionally surely you are aware of this:
Dometic AC Service Bulletin

I never said it was low charged from the factory. After months of use a small leak develops and cooling performance goes down until it stops. It will start freezing up as the charge gets low and then stop cooling completely.

I direct you to Dometic's service manual It's for the R22 systems but that doesn't change the fundamentals.
Page 109-110 (1111-112 of the PDF):

Inside Coil Freezes up Causes:
Ambient Temperature C22a 59
Ducting System A6a 2
Air Flow Obstruction C22j 60
Cold Control C7 30
Heat Gain/Heat Loss C22b 59
Thermostat Location A7 12
Cable Assembly C19 52
Fan/Run Capacitor C2 28
Motor C1 27
Low Refrigerant Charge C20c 57
Capillary Tube Blockage C20a 55
Comfort Control Center C18d 52
AC Power Module Board C17c 40

I had 2 of them that failed:

#1 the cooling capacity slowly got worse until it stopped cooling. Pretty much leak then low charge there since the compressor and fans still were working (no low pressure cutout like a car).

#2 it started icing up and then cooling capacity went in the toilet- not getting the trailer to 74 when it's under 85 outside and parked in the shade. Pretty much SOP that there's no 410 in it any more.

I've got 2 AC techs in the immediate family and when we told them what was going on - check filter (clean and I even ran without it as a test) and then low gas.

Since you can't gague these units it's not 100% certain but given they seem to be failing quite regularly and Dometic says 2013-2015 units have leaking issues, it's a safe bet that the gas was gone.