We are currently camping and it’s been pretty warm. Have the ac on pretty much constantly. Noticed when waking up this morning that the ac was ok but blowing out much less than usual. I’m with the fan on high, it’s blowing less than it usually does on low. And if I turn the thermostat up to turn the ac off, the fan Turns off but you can hear the compressor still running and that doesn’t turn off. Left it on for about 30 minutes before turning it off at the breaker. I did notice 2 days ago at the beginning of the trip that I’d the thermostat wasn’t so the way down to the bottom at 40 degrees , the ac wouldn’t come on. Thought that just might be a thermostat issue. I did leave the breaker off for about an hour and it seemed to have run fine, but then dropped down to below low fan again. Thought maybe, the coil was frozen, but then thought that wouldn’t change the flow of air I wouldn’t think. That confused me reading it back to myself, so please if you have questions LOL. Any thoughts?? Thanks in advance

From the 20 amp to the unit? I’m sorry, I’m not too familiar with diagnosing these things. I do have a volt meter tho.

1. Freezing of the coil will cause a LOSS of air flow2. IF the compressor does NOT shut off unless you kill the breaker, odds are the compressor relay is stuck ON. This is part of the upper AC control board and if this is true you have to replace the upper control board. 3. If you could post year/brand/model of RV and Brand and Model of AC unit. This would help us help you with more info. Doug

Can’t figure out how to post pictures on here but it’sa dometic. The trailer is a 2003 Starcraft star light 265rs. And thank you. Just turned it on after being off again for a while. Started low, but now is full blast. But the compressor does drill stay on.

Try turning the a/c off but leave the fan on high for an hour or so to thaw out the coil. Then turn the a/c back on. If it works then it could be the thermister is bad or fallen off the coil.Look at this playlist and you'll probably find what you need

Ac is acting funky. Anyone have any thoughts :)

16 Replies

wa8yxm
Explorer III
Jun 09, 2021
By all means check voltage.
Pull inner cover and look to see if evaporator is iced up
Pull outer covers (rooftop) and clean condenser.. NOTE the fan side is the side that cruds up on most makes so you need to remove an inner cover as well.
Shwthomas1975
Explorer
Jun 08, 2021
Thank you. It is almost a dedicated circuit. 2 exterior plugs one off gfci. And nothing ever plugged in to the other.
CA_Traveler
Explorer III
Jun 08, 2021
Yes. Be aware that if it's not a dedicated 20A plug/CB then the total amps drawn are the sum of all of the plugs on the circuit. Almost all home plug circuits have multiple plugs.
Shwthomas1975
Explorer
Jun 08, 2021
Side note. Am I ok to use my 20
Amp exterior plug to leave my camper plugged in for fridge and to keep the batteries charged? I don’t want to cause any other issues by doing so.
Thanks again
Shwthomas1975
Explorer
Jun 08, 2021
I’m sorry. I didn’t mean to confuse things. We were plugged into a 50 amp service, with an adaptor to my 30 amp plug. Microwave and everything else was fine. I am home now and when home only plug into my 20 amp exterior house plug (that’s all I have) and when i I
Turn the breaker on for the ac the condenser turned on and stays on still. With the ac off on the thermostat. I believe it’s something stuck open like someone suggested. Seems like something to get someone out here that knows what they are doing. If I am wrong, please let me know ;)
Thanks again guys. Stay cool. It’s sweltering out there today.
Appreciate all you guys
CA_Traveler
Explorer III
Jun 07, 2021
I agree - check the voltage and your 20A overheated hot plugs.

And Doug has extensive RV experience.
2oldman
Explorer II
Jun 07, 2021
dougrainer wrote:
NO EXTENSION CORDS AT ALL. Extension cords will drop the available voltage and a drop in voltage will cause a AC Compressor relay to "fuse" closed and cause the compressor to not shut OFF. Doug
I can't run my air at home on a 20a circuit. Too much voltage loss. But we don't know if OP has an extension cord.
dougrainer
Nomad
Jun 07, 2021
2oldman wrote:
Shwthomas1975 wrote:
From the 20 amp to the unit?
20 amp? That's your service? Voltage can be checked just about anywhere.

IF you are NOT on 30 amp service for most of your usage(you stated 20 amp), THAT usually means you are not connected to a correct supply source and that also means your supply voltage will drop when running the RV AC unit. RV AC units require a MINIMUM of 20 amp service just for the AC unit, not including other 120 appliances in the RV. That means you should be on 30 amp common RV service. NO EXTENSION CORDS AT ALL. Extension cords will drop the available voltage and a drop in voltage will cause a AC Compressor relay to "fuse" closed and cause the compressor to not shut OFF. Doug
2oldman
Explorer II
Jun 07, 2021
Shwthomas1975 wrote:
From the 20 amp to the unit?
20 amp? That's your service? Voltage can be checked just about anywhere.
dougrainer
Nomad
Jun 07, 2021
Shwthomas1975 wrote:
Thank you again. When I turn just the fan on the Ac compressor stays on as well. So it’s like the ac is on constantly, weather in ram only, or ac.
I’m sorry. In my phone and spell correct is killing it LOL
Air nor ram. And whether not weather. :)

Your upper AC control board is BAD. You need to replace it. Doug