AC cycling on and off repeatedly....

bobsue2

Active Member
This is the main unit in the LR....started making a clicking sound...now it runs for about 5 sec then shuts off...then immediately comes back on for another few seconds...does blow cold air though...any ideas...thanks
 

cookie

Administrator
Staff member
I would start by checking all the wire connections at both the AC and the T-stat. If all looks good and you have not already changed over to a digital T-stat, I would do so now.
If you are still having trouble after that, then it sounds like you need to make a call.

Peace
Dave
 

DougS

Doug S
You might want to check the electric from power source. I had a similar problem, winds up it was the campground site, moved on, problem solved. Just a thought.
 

bobsue2

Active Member
electric from power source

Thanks for the suggestion....this is our 4th time at this same site and never a problem before...

Was doing a little reading...are the original thermostats in the RV powered by batteries?
 

Bob&Patty

Founders of SoCal Chapter
Yes, the "T" stats are 12V. BTW, are you running the fan on high or low fan?? Running on the "low" fan setting can cause this. The evaporator coil can freeze up and make it very hard for the compressor to run. JMHO
 

TandT

Founding Utah Chapter Leaders-Retired
Do you have it set on auto?
Try it on high or low and see if it stops. When mine was close to optimum temperature it would stop and go to low, then it would decide to go back to high again and back and forth.
This was if I had a window or vent open generating warm air to the coach.
If everything was closed, or if I was more than a few degrees away fron my "set" temperature, it was not an issue.
 

TandT

Founding Utah Chapter Leaders-Retired
Thanks for the suggestion....this is our 4th time at this same site and never a problem before...

Was doing a little reading...are the original thermostats in the RV powered by batteries?

They are powered by the 12 volt from the coach. Not a separate battery.
When this on/off cycle is going on, does the display on the thermostat still show as normal, or is it blacking out?
 

57chevyconvt

Well-known member
Several things to consider: Low air flow, check return air filter; the thermo cycle swith has gone bad; the control board located in the return air plenum (wiring junction box) just above the inlet air filter has gone bad; low voltage on incoming powersupply; might consider adding kick start capacitor to assist compressor starting when campground voltage is low.
 

Rickhansen

Well-known member
I suspect a weak or loose control relay in your A/C unit interface board, probably the fan relay. You don't specifically say, but is the compressor continuing to run while only fan cycles on and off every 5 seconds?

I might also be inclined to rule out the thermostat by jumpering Rc (R) to the fan (G) and compressor (Y) terminals at the thermostat sub base, effectively bypassing the thermostat. If that stops the cycling, the thermostat is the problem.

Normally the defrost switch will only cycle the compressor and leave the fan running. Low airflow or dirty filter would cause freeze up of the coil after running for a while, not 5 seconds. A weak start capacitor will prevent the compressor and/or fan from starting from an off condition.
 
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