Air Conditioner - Montana Owners Club

Wmass camper · 07-22-2021, 12:02 PM

Biggest fear realized today. Left pup in RV with fully operational AC. Went kayaking, came back no AC. Dometic thermostat working but not turning on AC. Hubby gone to rescue camper who's truck is stuck on a boulder! Thought I'd help by picking some brains for ideas of what to look for. Breaker is not tripped. We are in VT hooked up to 30 amps. Main AC in kitchen area is the one not working. Rear AC is operational. Pup is fine.

**DQDick** · 07-22-2021, 01:18 PM

This is kind of strange because unless you have soft start kits installed on your AC units you usually can't run both at once on 30amps. It seems you still have power or the other AC wouldn't be running. Are both of your 50amp breakers engaged or is one of them thrown?

rohrmann · 07-22-2021, 06:31 PM

With only a 30 amp power source, you are unlikely to trip a 50 amp breaker. What is more likely is tripping the breaker of the A/C that isn’t working. The breaker can trip but not move the handle. To check this, turn off the running A/C, then turn off fully the breaker that feeds the A/C that isn’t running and then turn it back on, then try to run the A/C that wasn’t running.
It would also help knowing what rig you have, model and year.

Ram Montana High Country · 07-22-2021, 10:52 PM

Since they are in the NE - unit may only have one AC. If the fan is running but not cooling-try switching it to Heat Pump and run it till you feel heat from vents. This means unit froze up. Or switch the AC to OFF for a minute and then turn back on.

Ask me how I know ... been doing both on this trip even after putting in some Micro Air TSTATS.

But the dealer can't make it fail ...

RMcNeal · 07-23-2021, 04:24 AM

If you have the newer Dometic capacitive touch thermostats like our 2019 3791RD, then you can turn off the unit at the thermostat, wait for a few seconds and turn it back on. It should fire back up after a short delay. That's the problem we were having constantly with ours until we put in the Microair thermostats.

Andy Smith · 07-23-2021, 07:00 AM

I will add another vote for replacing the dometic t-stats with the micro air. I did the forward one a month ago because it would just stop kicking on the AC even though it was nowhere near the set point. Since replacing, I haven't had any issues even with icing up. I figured I'd hold off on the galley t-stat until it started to fail, and I think we're there. Now it will mis-register the temperature as continually warmer than the air and just run the AC till you turn it off and back on again.

Ram Montana High Country · 07-23-2021, 09:02 AM

I’ve still had the NON start issues with Microair. Less often but still. A good feature is it shows cabin temperature

Bob and Jeannette · 07-28-2021, 02:53 PM

Power shedding, you need 50 amps to run both without a soft start.

Byron B · 07-28-2021, 04:11 PM

Are these the ones Amazon sells for $259?
If so, anyone aware of a better price? Our Dometic tstats are worse than a case of a clogged up black water tank…..

firestation12 · 07-28-2021, 06:03 PM

Quote:

Originally Posted by rohrmann

With only a 30 amp power source, you are unlikely to trip a 50 amp breaker. What is more likely is tripping the breaker of the A/C that isn’t working. The breaker can trip but not move the handle. To check this, turn off the running A/C, then turn off fully the breaker that feeds the A/C that isn’t running and then turn it back on, then try to run the A/C that wasn’t running.
It would also help knowing what rig you have, model and year.

Rohrmann is correct about a breaker doesn't always look tripped. As he suggested, always manually reset any circuit breaker suspected of being tripped. Also note, there is a thermal limit switch inside each of the a/c compressors. If one a/c is running, and the 2nd a/c tries to start (while plugged into a 30 amp service), the 2nd a/c compressor may stall and cause the internal limit switch to open or the starting amps of the 2nd unit's compressor will cause the dedicated a/c breaker to trip. If the compressor's internal limit switch opens, it will not automatically reset until the compressor cools off. This can take several minutes, perhaps as much as 30 minutes. As long as the 1st a/c is running, the 2nd a/c will be forced into a continuing cycle of trying to start on reduced current and locking up, causing the internal thermal lockout to trip. Trying to run 2 a/c units on a 30 amp service, with the fridge set to cool on electric, the voltage converter operating, and water heater set to electric, is a sure fire recipe to cause problems in the camper.

rames14 · 07-28-2021, 06:34 PM

Wmass Camper, did you ever find out what caused your AC to malfunction? I’m guessing it was the 30 amp, but there were a number of ideas and no reply back from you.

lj_cox · 07-28-2021, 06:37 PM

We have this problem from time to time with our rear AC. I think based on experience it's humidity related but several repair shops have been unable to locate an actual issue. Temporary fix is to turn the thermostat off and back on again; if it shuts off again, leave thermostat off for 20 minutes before restarting. Cleaning the filters on the air returns seems to help a lot, also.

kjohn6363 · 07-29-2021, 10:42 AM

Govee App keeps you connected so you can check on the temp in your camper when away. They connect to Wifi and you access on your phone

Andy Smith · 07-29-2021, 10:47 AM

Quote:

Originally Posted by Byron B

Are these the ones Amazon sells for $259?
If so, anyone aware of a better price? Our Dometic tstats are worse than a case of a clogged up black water tank…..

I haven't seen a better price on the Micro Air ones. They're pricey, but they work well, and I like being able to check them when I'm away to make sure the pets are comfortable.

432bartman · 07-29-2021, 11:50 AM

If you leave your pets inside a lot, get an RV pet temperature alert system. It doesn't take long for a pet to die from the heat.

Wmass camper · 08-13-2021, 06:12 AM

We turned the AC off and back on again, which seemed to relieve the issue. Would be helpful if we knew what the inside temperature truly is! However, we have ordered the MicroAir thermostat and waiting for it to come in. Seems to be a shortage of units, or they are making them as the orders come in. Ordered a week ago and no shipping date yet. Thanks for all your assistance.

bshgto · 08-13-2021, 06:48 AM

Quote:

Originally Posted by Wmass camper

We turned the AC off and back on again, which seemed to relieve the issue. Would be helpful if we knew what the inside temperature truly is! However, we have ordered the MicroAir thermostat and waiting for it to come in. Seems to be a shortage of units, or they are making them as the orders come in. Ordered a week ago and no shipping date yet. Thanks for all your assistance.

I ordered one a week ago also and no ship date yet. It would have been nice if they would have told us that there is a backlog or part shortage before ordering as Amazon has them atleast they did and with 2 day shipping I would have paid a little more for one as we are leaving on a trip.

Update: Amazon is now advertising a Sept 10 - 20th delivery date on the 351 model. I`ll bet people aren`t showing up for work, can`t imagine why?

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