Odd possible AC issue?

[Lost_my_beer]

Cant seem to find anything while searching. I have a bit of an unusual problem. Actually, I am not even sure if it is a problem, or maybe just the way the system is supposed to work...
I have a 2020 Cyclone with triple Dometec units. Just finished our fourth trip. Didnt notice on prior trips, but we have been using 50 A service until now.
Camped last week using 30 A. I know you cant use 3 (or sometimes 2) AC units at the same time while on 30. I used the main cabin and forward bedroom. Both would sound like all is working normal, but each one would cycle on and off frequently. Sometimes I could hear the condenser kick on after about 45 secs of the fan on, and sometimes not. It was not that hot (about 85), and it took waaaaay too long to cool down and keep cool...like hours. Usually, even in FL heat it takes only about an hour to get comfy. Didnt feel like the air coming from the vents were much cooler than room temp, if at all. I am a bit gun shy because right before I traded my last 5er in I had an AC unit replaced that **** the bed.
Question. When using 2 units on 30 Amps, will this happen? Is it on some priority circuit? I always thought it would just blow a breaker if overloaded with the extra ACs. Am I wrong?
Thoughts? Normal?
Thanks.
Troy

 

[danemayer]

Hi Lost...

Your Cyclone has a Precision Circuits System (PCS) that manages power consumption. It automatically detects 50 amp or 30 amp service, or generator output and adjusts accordingly. If you plug into less than 30 amps, for it to work correctly, you'll need to manually notify the PCS of the available power.

When plugged into 30 amps, if ALL that was operating on 120V AC was the two A/C units, it's possible they might both run. But if other devices were drawing power, the PCS would shed power to 1) water heater, 2) rear A/C, 3) front A/C, etc. to keep total power usage under 30 amps.

When the A/C units are shed, the blowers will keep running, but the compressors will shut off.

One thing that's not obvious is that your Power Converter (120V AC to 12V DC) draws power all the time. Generally 1-2 amps. But it can draw more than 15 amps from time to time to supply 12V DC power to lights, control boards, and to charge the batteries.

You can read more about the PCS on pages 14-16 of our owner-written Electrical User Guide. And even more info is in this folder.

 

[Lost_my_beer]

That is great news! I was hoping it was something like this, but really had no clue. Thanks for the heads up.
Troy

 

[Lost_my_beer]

Thanks again for that link. Very informative.
Out camping and am noticing the same issue. 50 Amp service and no other A/Cs running overnight (while this happens anyway). Temp set to 73 auto. Bedroom unit will start and after about 30-45 secs will shut off. No compressor start up. After 60-90 secs it tries to restart. Same thing. It will do this 5-7 times before the compressor kicks on and works normally. Bedroom does get warmer. If I turn off AC or select a lower, or even higher, temp compressor kicks on and everything is 5 by 5. OAT about 65-70.
I understand that the unit should do this if it detects a freeze up and such, but with low humidity and temp, and only this unit running I suspect a problem. Dealer says it works normally. I disagree.
The link did mention to take off inside cover and reseal up vents to make sure no co contamination, which I will try.
Any other ideas? Could it be a circuit board or thermostat? Any easy way to test both? Looks like its just me and the dog left to fix this!
Hope yall have a great Thanksgiving btw.
Troy

 

[wdk450]

A standard test that most AC techs do is with the AC running and cooling, with indications the compressor is ON (current draw, noise, or vibration) the temperature of air coming out of the vents nearest the air conditioner unit should be 20 degrees or more cooler than the temperature of the air going into the air conditioner unit air return.

I have a kitchen food thermometer like this that works well for cooking, refrigerator checks, or air conditioning checks:
https://www.target.com/p/taylor-com...XUHMPREio2NVM26ERzIaArKPEALw_wcB&gclsrc=aw.ds

 

[Lost_my_beer]

Problem is that my issue is the compressor not coming on when I think it should. When its off, it is warm...just a fan. When the compressor kicks on, it cools perfectly. No need to measure temps.
Troy

 

[jmarnell]

Thanks again for that link. Very informative.
Out camping and am noticing the same issue. 50 Amp service and no other A/Cs running overnight (while this happens anyway). Temp set to 73 auto. Bedroom unit will start and after about 30-45 secs will shut off. No compressor start up. After 60-90 secs it tries to restart. Same thing. It will do this 5-7 times before the compressor kicks on and works normally. Bedroom does get warmer. If I turn off AC or select a lower, or even higher, temp compressor kicks on and everything is 5 by 5. OAT about 65-70.
I understand that the unit should do this if it detects a freeze up and such, but with low humidity and temp, and only this unit running I suspect a problem. Dealer says it works normally. I disagree.
The link did mention to take off inside cover and reseal up vents to make sure no co contamination, which I will try.
Any other ideas? Could it be a circuit board or thermostat? Any easy way to test both? Looks like its just me and the dog left to fix this!
Hope yall have a great Thanksgiving btw.
Troy

Not sure if this is your problem or not, but we were having issues with our Cyclone's living room AC cycling off the compressor and not restarting. If I shut down the thermostat and restarted the system, it would then work normally. Our Mobile RV Tech finally diagnosed a bad relay in the AC's control box. He replaced the control box and we haven't had any problems since then. Our AC is the Dometic Brisk II. The control box is a grey box about 5 inches square, and you have to remove the ceiling grill to get at it.

 

[Lost_my_beer]

Interesting. Might go take a look. Wonder if there are 3 diff circuit boards, or just the main and the front and aft units are wired through it too.
Troy

 

[jmarnell]

Interesting. Might go take a look. Wonder if there are 3 diff circuit boards, or just the main and the front and aft units are wired through it too.
Troy

Each AC has its own control box.