Penguin AC "Short Cycle"

[vakthund]

My Cyclone's main A/C unit keep cycling on/off about every 8-10 minutes (give or take). When the compressor is running the unit cools fine (~15-18º lower than intake) but the compressor will only run for about 8-10 minutes. The fan goes to high for ~20 seconds and the units shuts off with the thermostat indicating “Compressor Delay” (hourglass icon). After about 2 minutes the process repeats.
I have cleaned the condenser and evaporator coils, the fan spins easily, the frost sensor has accurate reading (at least at 70ºF), filters are clean, no vent obstruction, the inside and outside temperature probes are accurate (within 2º), no debris in the unit, no leaks, no water, weather strips are fine, and my EMS is not reporting any electrical issues. No errors or anything unusual on the thermostat.
Any suggestions for troubleshooting further? I have no clue why the compressor shuts off. It is 81º outside and 78º inside which is unbearable for a Viking. The air is not blowing on the thermostat, it is set to 72º and interior temperature reads 78º.


Thank you.

 

[wdk450]

Have you checked the air intake box to see if there are any cold air leaks coming across from the cold air going to the ducts? On 1 You Tube Video on RV air conditioning, I saw the technician aiming an infrared thermometer with an aiming laser around the return air box (with the inside AC cover removed) with the system running in cooling mode, and finding small places where cold air WAS leaking across. This box needs to be thoroughly taped up with METAL duct tape to seal up any potential cold air leaks. Also, the cold air box and ducting should be also sealed up with metal duct tape in the same way.

The refrigerated escaping cold air in the normally warm air return system can cause the evaporator to freeze up and the freeze sensor to turn off the compressor.

Post #5 in this thread has some good pictures inside the Air conditioner inside access showing the metal tape sealing it up.
https://heartlandowners.org/showthread.php/1069-AC-air-flow-problem-SOLVED

 

[vakthund]

Have you checked the air intake box to see if there are any cold air leaks coming across from the cold air going to the ducts?

Thank you for the suggestion. I took the ceiling cover down and taped up anywhere air might have come through. Unfortunately my problem persists.
Also check the coils and they are definitely not freezing up.

 

[jerryjay11]

Thermostats have a built in delay to prevent restarting a compressor on a load. Some may be in the control board. You could try removing the thermostat and jump out the wiring to test the compressor. (you'll need a wire diagram of your T-sat)

If problem still exists then the problem could be in the control board or compressor overload protector. Not knowing the amperage the compressor is running at makes it a guessing game between the control board, t-stat, and compressor. A multimeter would tell you if you are losing voltage to the compressor from the board or the amperage is too high. Checking voltage at the compressor: - if voltage present at compressor when it shuts down then the overload (OL) device is opening. - If voltage is not present when compressor shuts down then the board is suspect or the t-stat is not calling for cooling. This is why you should jumped the t-stat.

So in review:

jump out t-stat: everything works fine - t-stat bad

jump out t-stat: problem persists - board or compressor problem (weak OL or compressor issue)

Determine board or compressor issue:

jump out t-stat: no power at compressor - board issue

jump out t-stat: power at compressor - compressor/OL issue

Note: because the AC fan can be ran independently of the compressor at the T-stat you'll need to jump power to the fan circuit at the t-stat as well.

When troubleshooting I always start at one end (power) or the other (in this case compressor) and work in the opposite direction to isolate where the issue is.

 

[vakthund]

jump out t-stat: everything works fine - t-stat bad

jump out t-stat: problem persists - board or compressor problem (weak OL or compressor issue)

Determine board or compressor issue:

jump out t-stat: no power at compressor - board issue

jump out t-stat: power at compressor - compressor/OL issue

Note: because the AC fan can be ran independently of the compressor at the T-stat you'll need to jump power to the fan circuit at the t-stat as well.

When troubleshooting I always start at one end (power) or the other (in this case compressor) and work in the opposite direction to isolate where the issue is.

Thank you, I’m back in Florida finally so I will troubleshoot. Appreciate the help.

 

[vakthund]

When troubleshooting I always start at one end (power) or the other (in this case compressor) and work in the opposite direction to isolate where the issue is.

Thanks again for the help. The board is cutting the power to the compressor (can hear the relay and I checked the voltage). I can’t short the thermostat as it is digital (Dometic CCC2) so I’m unsure if it is the board or thermostat. Going to see if any campers here will lend me their thermostat for an hour is so. Just need to brush up on my French a little.
Puis-je emprunter votre ehh ... thermostat?