Yahoo Message Number: 114669 (http://groups.yahoo.com/neo/groups/country-coach-owners/conversations/messages/114669)
We have 2 15,000 BTU Dometic A/C's. They have been freezing up since we had them installed. It is a ducted system and we have adequate Numbers of vents per Dometic. The problem essentially went away when I opened the Exit air vent on the AC thereby reducing the back pressure. Now it's starting to freeze up again. On a House AC unit I cleaned the inside condenser and that solved the problem. Used a commercial condenser cleaner. Took a look at the MH AC and that condenser is not easily accessible. Not much room on the input sied and the squirrel cage fan covers the exit side. Not sure how easy it is to get to from the top. Before I go any further though I would query the folks at Group to see if I can get any input.
The way Dometic addressed the problem doesn't seem to work There is a freeze sensor, not exactly sure what it does. If you shut the compressor off for about 5 minutes and then turn it back on the problem goes away.
We use the ducts when we are in the MH and then open the direct vent if we go away for awhile. Works most of the time.
Judy n Joe
96 Intrigue 10578
Yahoo Message Number: 114670 (http://groups.yahoo.com/neo/groups/country-coach-owners/conversations/messages/114670)
Ok I've been in HVAC for 45 yrs so it is easy to determine the problem if we both speak the same language
First are they heat pumps or straight air conditioners?
Secondly there are 4 parts to the refrigeration cycle 1) compressor
2) condenser 3) evaporator 4) metering device
I assume this is a R-22 system if so there should be a 20 degree split from supply to return air
Freezing of the evaporator can be caused by low air flow low refrigerant or a bad metering device
So start by determining the temperature split then we can go from there
Yahoo Message Number: 114713 (http://groups.yahoo.com/neo/groups/country-coach-owners/conversations/messages/114713)
When it's not frozen exit air was about 26 def F lower than the input air (Last time I measured) Went to measur again this AM and my thermometer is not functioning, will get another. AC cools very good until it freezes. It freezes quicker when using the ducting. Last year it did not freeze when using the Exit vent on the AC. When iI talked to Dometic they attributed the freezing (ducts) to higher back pressure. I'm going to clean the evaporator with a vacuum cleaner and brush.
When I had this problem on a residential unit, I cleaned the evaporator with a cleaner and air hose and solved the problem. The MH AC is a straight AC, does not have a heat pump mode.
I will recheck when I get a new thermometer.
Judy n Joe
98 Intrigue 10578
Yahoo Message Number: 114739 (http://groups.yahoo.com/neo/groups/country-coach-owners/conversations/messages/114739)
Got a replacement thermometer. Turned on the A/C motorhome was warm. Return air temp was around 80 deg F and supply air Temperature was 44 deg F. I've had the bottom vent open on the a/c yesterday and it didn't freeze up in about 4 hours. Doesn't happen all the time. It does happen almost every time when we close the bottom vent and use the ducting with all of those vents open.
Not exactly sure on things like rel humidity etc
Judy n Joe
98 Intrigue 10578