AC fan cycles Low to High and back to low

[farside291]

Does anyone else's AC do this? When set to Auto, the fan will change from High to Low speed for a few minutes. Then as temps in the trailer rise, the fan will cycle back to High. Then the whole process keeps repeating itself. When the fan is changing speed its like the AC momentarily shuts down then restarts. I am not even sure if the compressor is shutting down or just the fan. It's more annoying than anything else to the point where I just take it off Auto and either set it to High or Low speed. Would swapping the thermostat to one of the newer models stop this?

 

[danemayer]

Ours does the same. Try setting the thermostat a few degrees lower.

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[farside291]

Thanks, Yes, that is a good idea. Do you have the same thermostat?

 

[TravelTiger]

My SIL's 2012 BH does this too. Annoying. Will watch to see if there is a solution?


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[danemayer]

Thanks, Yes, that is a good idea. Do you have the same thermostat?

Yes, but ours is white. It's the Dometic Single Zone LCD.

 

[farside291]

My solution, like Dan said is to lower the set point or set the fan to low or high. Do you think the compressor shuts down or just the fan?

 

[NWILSON]

I may be misunderstanding your symptoms but if the A/C unit is shutting off for just a few seconds then restarts it could be the frost sensor has come out of the coils. An easy fix if that's the cause

 

[alsams]

Mine does the same thing. My theory is that it has reached the thermostat set point and is in a fan-only mode with the compressor shut off as part of a shut down process and then gets turned back on by the thermostat. As it continues to cool in the coach, it eventually stops doing it. It is annoying.

Al

 

[danemayer]

I've also noted that sunlight coming in the window in the entry door often heats up our thermostat. So it runs on max for a while, and then changes fan speed and pauses as it closes in on the set point. A moment later, without the benefit of max cooling, the thermostat warms up and has to cycle back around.

 

[Sowie]

I just recently had two of my three ac units replaced under warranty and repair guy said on ducted rv’s to always run one of the ac units on high fan and to alternate the one set on high to be opposite the area you occupy at that time. Like run the bedroom ac fan on high during the day and living room ac on high at night so not to bother you with fan noise while sleeping. He said air circulation is key to keeping comfort levels at optimum. I tried and it does seem to help and I didn’t notice ac’s cycling doing the shut down and starting back up like they do when in auto fan.


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[travelin2]

Regardless of whether we’re operating both ACs simultaneously or individually, the LR unit fan is on auto and the BR fan is on low or sometimes med.
We also run opposing ACs to occupied areas unless temps dictate we need both simultaneously.


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[Lou_and_Bette]

My SIL's 2012 BH does this too. Annoying. Will watch to see if there is a solution?


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Erica, my 2015 BH does this occasionally and I was concerned but, at last years National, I was talking to a Dometic rep and he explained this up/down cycling. He indicated the system is designed this way after it has been working very hard for extended period, as the temp approaches the set temp, it drops into low gear to finish off the last degree or so. However, on initial set up when the inside is very hot or on those extremely hot days, the inside temp goes up faster than the low speed can bring it down so it kicks back up into high speed. Dan had the solution, lower the set temp and it will not cycle as often probably because it never gets that close to the setting if you set it low enough.

 

[TravelTiger]

Thanks, I'll pass this on!


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[rjr6150]

Auto Fan
When auto fan is selected the fan speed will vary depending on the
difference between the temperature set-point and the room tempera-
ture. In auto fan the compressor and fan cycle On and Off with the
thermostat.
When the difference is:
>5º
The fan operates on HIGH
<4º
The fan operates on LOW