Dometic AC fan cycles compressor runs

[unsichtbarre]

When running the dometic air conditioner on our 24-ft citation Sr, I have noticed that the fan will shut off for 3 to 5 seconds at a time while the compressor keeps working. This happens in dry and humid climates as well, so I don't think it's evaporator icing.
Has anybody else experienced this does anyone have any ideas?
Thanks,
John

[16ACE27]

In my experience - not normal.

[MLP]

I think that it happens a lot more than you would think. It happened to my old front AC, rear AC, and also the new front AC. I turn off the rear AC and then that fan cycling stopped. I think the AC units get too cool and this caused the problem.

[16ACE27]

Originally Posted by MLP

I think that it happens a lot more than you would think. It happened to my old front AC, rear AC, and also the new front AC. I turn off the rear AC and then that fan cycling stopped. I think the AC units get too cool and this caused the problem.

If it got too cold, why would the compressor continue to run?

The only time the fan should cycle off is when the compressor also cycles off.

[TheGoodLife]

Possibly a faulty thermistor (freeze sensor)?

[Judge]

Does your coach have the FireFly (Multiplex) system?

My Magnitude has it with Coleman-Mac A/C units and I had issues when it was new where the compressor would run and the fan wouldn’t or the fan would run but the compressor wouldn’t even though the thermostat was calling for cooling.

If I shut down the 12V system and forced a reboot, it would work ok for a while and then start doing it again. After troubleshooting with Firefly, they determined it was a faulty G7 Control Board (mainboard). I was able to get it replaced by Thor under warranty and it has worked normally ever since.

[unsichtbarre]

I thought I would follow up on this post as we're in Puerto Penasco right now and using the AC 24/7.
Normally, I keep the fan speed on the dometic thermostat set to auto, otherwise the AC fan will run when the furnace runs.
The other day I noticed that when the interior of the coach begins to approach the set point of the thermostat is when the fan stops running but the compressor continues. A theory occurred to me that it might be trying to switch from high fan speed to low fan speed, and failing to make the switch over although it will run on low if I select that on the thermostat.
Nonetheless I selected high fan instead of Auto and the behavior of the fan stopping while the compressor continues to run has ceased.
I guess when using the AC from now on I will manually select the speed, probably high, and just leave it there. The only downside to this is the fan runs all the time even if the thermostat is not calling for cool, it just shuts down the compressor.

Thanks,
John

[16ACE27]

Originally Posted by unsichtbarre

I thought I would follow up on this post as we're in Puerto Penasco right now and using the AC 24/7.
Normally, I keep the fan speed on the dometic thermostat set to auto, otherwise the AC fan will run when the furnace runs.
The other day I noticed that when the interior of the coach begins to approach the set point of the thermostat is when the fan stops running but the compressor continues. A theory occurred to me that it might be trying to switch from high fan speed to low fan speed, and failing to make the switch over although it will run on low if I select that on the thermostat.
Nonetheless I selected high fan instead of Auto and the behavior of the fan stopping while the compressor continues to run has ceased.
I guess when using the AC from now on I will manually select the speed, probably high, and just leave it there. The only downside to this is the fan runs all the time even if the thermostat is not calling for cool, it just shuts down the compressor.


Thanks,
John

Not a downside in my book, especially at night.