Dometic AC Compressor won't stay running

[Harlech]

Hey all! Been scouring the internet with not luck trying to find an answer as to why my AC unit (A 13,500btu) will not keep the compressor running.

First the nitty gritty details:
40' 5er with 2 AC's
The living room in a 15k and has no issues
The bedroom is a 13.5k and has intermittent issues I will explain below
Both being controlled by a Dometic CCC2 (Which I have replaced for another issue)
On 50amp shore power, have had no known power issues thus far and this problem has surfaced on two separate locations

The problems:

First off, I have replaced the CCC2 but that was due to a faulty temp sensor that would cause the bedroom inside temp sensor to read at 32 degrees and thus the thermostat wouldn't even try to run to the AC in the bedroom. The living room has always ran fine, and never had an issue. Since replacing the thermostat the inside temp has read correctly and when the temp exceeds the set point it turns on the AC in the bedroom which leads to the problem.

Note: This is an intermittent problem, which makes it worse. But 1 out of around 5 times the AC will function perfectly, and sometimes for days at a time.

When the AC comes on the fan motor fires up and starts moving air no problem. After a start up delay of 10-15 seconds the compressor will then kick on. Here comes the moment where I hold my breath. After the compressor comes on it will either stay running perfectly and cool the room to the desired set point OR after 20-30 seconds (Which leads me to believe it isn't a starting issue) the compressor will then turn off and remain off. It isn't like the compressor is trying to cycle, the AC will run the fan from here to eternity trying to cool the room with no compressor engagement.

Things tested and tried:
Voltage. I have plugged my multimeter into the AC (electrical) system and monitored for voltage drop and haven't seen any. This problem has manifested at two different locations (One in Oklahoma and one in Texas) so I don't think it is a shore power issue. That being said, I don't have an amp clamp available at the moment so I haven't checked amperage.

Freeze sensor. I have relocated the freeze sensor from where the installers had put it (in the middle of the evaporator) down to the location outlined in the manual. (Awhile ago, but I think it said between 1st and 2nd coil on the lower left hand side facing the evap from the outside).

Baffling. I taped up the baffling better between the intake and outlet due to reading about cold air bleed over causing it to cycle. It was a hail mary, no luck.

This problem happens if I am pushing air through the ducts or with the AC dump open on the bottom side. Doesn't matter.

That is all I can think of off the top of my head. At this time I am at my wits end. Unfortunately my wife and I are full timing or else I would take it in. Due to us being between homes I am to the point where if it warms up it would be cheaper for me to just replace the unit myself but knowing that it works a part of the time makes me think there has to be something I am missing or some part of the unit that is just not functioning correctly.

Any help will be greatly appreciated!

Thanks,
Kyle

[carl2591]

wrong product.. looking for DMC1401

[Harlech]

dougrainer wrote:
As you figured out, you need the clamp on Amp meter to watch the compressor amps and what those amps are in that 20 to 30 seconds. Once the compressor starts there is no reason to suspect the start capacitor because it did its job. There is a limit on the compressor and the odds are your compressor is bad. The amp draw will show you that. IF the amps do not go over 15 amps and the compressor still kicks off, then the Freeze control is probably defective. IF you have a system doing what you have, then the compressor should attempt to start every few minutes. If not, that points to something telling the compressor to not start---The freeze sensor. Since you full time, a freeze sensor is cheap and easy to replace. I would do that regardless of your amp meter. Take that out of the loop by replacing it. You can also trace the freeze sensor to where you can separate the 2 wires and cut the wires and splice them together on the circuit board side. That will bypass the freeze sensor. Doug

Since you have 2 units, just swap the freeze sensors.

This is good advice, Doug. I wouldn't of thought of bypassing the freeze sensor as a test but that makes sense. Amp clamp will be in today so I will probably hold off on testing until after the Holiday when I can find the time to go up and test both at the same time.

I actually ordered a new freeze sensor since they are only $15, this might help explain why some of the issues are erratic.

Thanks again and have a Merry Christmas!
-Kyle

[dougrainer]

As you figured out, you need the clamp on Amp meter to watch the compressor amps and what those amps are in that 20 to 30 seconds. Once the compressor starts there is no reason to suspect the start capacitor because it did its job. There is a limit on the compressor and the odds are your compressor is bad. The amp draw will show you that. IF the amps do not go over 15 amps and the compressor still kicks off, then the Freeze control is probably defective. IF you have a system doing what you have, then the compressor should attempt to start every few minutes. If not, that points to something telling the compressor to not start---The freeze sensor. Since you full time, a freeze sensor is cheap and easy to replace. I would do that regardless of your amp meter. Take that out of the loop by replacing it. You can also trace the freeze sensor to where you can separate the 2 wires and cut the wires and splice them together on the circuit board side. That will bypass the freeze sensor. Doug

Since you have 2 units, just swap the freeze sensors.

[Harlech]

As an FYI, I have an Amp Clamp on order so once I get back from the holidays I will see what the current draw is on the compressor. (In SW Texas we still use the AC in December some days, lol!)