Dometic a/c short cycling at night

Recently purchased a 2019 22crb northtrails. having issues with a/c turning on and off every 15 to 20 seconds only at night. System works fine during the day. It is on auto position. Is anyone having the same issues and what have you done to fix it?

Thanks,
John P

Here is an article on RV air conditioner short cycling. With the symptoms you describe, I am wondering if you are having a freezing evaporator cooling coil on the rooftop unit. The usual installed Dometic air conditioners have a "freeze sensor" that clips into the evaporator coil that turns off the compressor (cooling producer) when the evaporator (and its associated air humidity condensate water) freezes up.


See Figure 12 on Page 9 of this manual from our Forum manuals library for info on the freeze sensor:
https://manuals.heartlandowners.org...nits/Dometic/Brisk-Air-AC_installation_EN.pdf

Good Luck!!!

Do you have the blast gate open? Might also check to see if the cold air plenum is sealed off from the return air plenum.

Have you taken off the AC shroud on the roof and inspected the coils? Dometic makes an AC coil cleaner. I had to do this. Boy does this clean the coils. You also should do the internal coils as well. You have to pull the foam cover off from the roof side and I put towels and then a tarp to protect the inside. Makes an old one run like new, because it become efficient again. Dometic coil cleaner is a no rinse cleaner. You can find it on Amazon.

mlpeloquin said:

Have you taken off the AC shroud on the roof and inspected the coils? Dometic makes an AC coil cleaner. I had to do this. Boy does this clean the coils. You also should do the internal coils as well. You have to pull the foam cover off from the roof side and I put towels and then a tarp to protect the inside. Makes an old one run like new, because it become efficient again. Dometic coil cleaner is a no rinse cleaner. You can find it on Amazon.

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I did clean the coil that was visible when I took off shroud. did not check coil under the foam. I will get a can and clean the coils. Thanks!

hoefler said:

Do you have the blast gate open? Might also check to see if the cold air plenum is sealed off from the return air plenum.

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Yes the blast gate is open. I will take off cover to see if it is sealed.
The a/c runs like a champ during the day. only short cycles at night. Earlier post said the coil could be freezing due to high humidity. Thanks for your feedback!

john pfeiffer said:

Yes the blast gate is open. I will take off cover to see if it is sealed.
The a/c runs like a champ during the day. only short cycles at night. Earlier post said the coil could be freezing due to high humidity. Thanks for your feedback!

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Close the blast gate, it is sucking in cold air

Short cycling IMO is because the set temp & actual temp are too close to the same. “Runs like a champ” during the day because it’s working continuously to cool the RV.
While some of the previous comments may be correct, I suggest dropping the set temp lower by a few degrees when the unit starts to short cycle

travelin2 said:

Short cycling IMO is because the set temp & actual temp are too close to the same. “Runs like a champ” during the day because it’s working continuously to cool the RV.
While some of the previous comments may be correct, I suggest dropping the set temp lower by a few degrees when the unit starts to short cycle

Click to expand...

Makes sense I will try that. thanks