A/C Works Intermittently

[Lynxman]

I have a 2011 Mountain Aire 4314 with 3 Penguin roof Air units. I am currently at an RV Park with only 30 Amp service so I have been trying to cool off our Coach using only 2 A/C units in Zone 1 and Zone 2 with not much success. Both of these units have been replaced within the last 2 years and blow cool air when they are running however when it' warm out (80 ish) Zone 2 unit only runs for 2 or 3 minutes and then shuts down for 15 - 25 minutes. It does run much longer when temperatures are lower.



Zone 1 runs longer but as the temperature gets warmer (80+) it will shut down after 15 minutes or so but without reaching the temperature settings I have set on the thermostat and then starts up again after about 5 minutes . In cooler temperatures it seems to run much longer (at least an hour) before stopping for a 5 minute break and then starting again.



In the past hour I have also turned on Zone 3 but it is behaving like Zone 2 and has only run for a couple of minutes at a time. Zone 3 unit is an original 2011 unit.


The only common piece I can think of is the thermostat control unit (Dometic). It's hot in here for more reasons than one, the DW is fuming!!


Does anyone have any ideas?


Thanks,
Hugh

[Lynxman]

Quick update. I have turned off Zone 3 because even with my inverter feed to cover off additional Amperage something won't allow all 3 tu run together so I have closed the bedroom door so I can have as much cooling as possible in the living space.


Also inside temperature is rising at a rate of about 2 degrees per hour.

[DT4452]

Doesn’t sound like a thermostat, I would look at wiring diagram and bypass it to check. Have you tried running the generator? Or check the voltage with ac’s running, it might be low volts at the pedestal
If it’s the compressors overheating from low voltage you can try Easy Start kits.
If it is the condensers overheating they might be partially plugged? A light mist of water to cool the condenser to check that.
Good luck

[Lynxman]

Thanks for the reply. They are very strict about running generators here but I went to my immediate neighbors and explained the situation about trying to determine where the problem was and they all agreed that I could run it for about 20 minutes and all my A/Cs worked fine on generator power so I checked the voltage while back on shore power and it drops to about 115V when I put 2 A/C units load on it. It was at 126V with no load. Would the Easy Start kits solve this issue?

[vito.a]

When your A/C units are starting up they will pull a lot of extra amps.
You really need a parking spot with 50 amp service.
An RV 50 amp service delivers up to 100 amps while a 30 amp service only delivers 30 amps.

[d23haynes57]

Have you tried running only 1? Have your turned off everything else including the battery charging and refrigerator? Where are you checking the voltage? 115volts under load is still good. There may be an additional voltage drop in the RV including the transfer switch. You mentioned one the AC can run off the inverter. That would mean 2 transfer switches between the park power and that AC. A 30-amp circuit is only 3,600watts. 2 ACs is pushing the limits especially in warmer weather as the AC's need more power under the increased load.

[Ray,IN]

No, easy-start devices will not help with running ability, only start-up is managed.
Shore power voltage with nothing running is of little use, what you should measure is amp-draw from each A/C unit, plus voltage at the same time.
This will give you an accurate picture of electric draw of each A/C unit. As voltage decreases, amp-draw increases.
What are the sizes of your Penguin units?
This is wattage requirements of each size:

running W + additional startup W

RV Roof-Top AC (11,000 BTU) 1,010 W 590 W
RV Roof-Top AC (13,500 BTU) 1,500 W 1,000 W
RV Roof-Top AC (15,000 BTU) 2,000 W 1,300 W
As you see, running 2 A/C units is pushing the limit of a 30A service when supplying adequate voltage and amperage. Then add the unseen power consumptions, battery charger, lighting, refrigerator and water heater (if running on electric) + misc. stuff. A real biggie is DW using a hair dryer, it equals one air conditioner running.
source: https://generatorist.com/list-of-ele...-wattage-usage


The real problem is compressor motors being slowly damaged from running on low voltage, this damage is very slow and permanent, the motors never recover.
The low and high voltage limits are stated on the nameplate of each device.

[DT4452]

https://www.softstartrv.com/
This brand is interesting, they say it will run 2 ACs on a 30 amp service. I think I’ll wait for the one they are developing for use with the transfer switch mainly because I have the basement AC with 2 compressors.
Kinda pricey but guaranteed with 90 days to try it and send it back if it doesn’t do what they claim, you can’t beat that.
Dave

[Old Scout]

Opinion, 30 amp=service is minimal for your rig in warm weather. You would need to shut-off EVERYTHING else [specifically: battery charger, water heater, no microwave] to run two ACs continuously. Your rig is new enough to have an energy mgt system {EMS}, that automatically sheds appliances. It would also be curious to see what your voltage is with both units running. Suspect its well below 110v, which makes your amp issues even worse and its bad for your AC units.
PS--what Ray said [post #7}

[Lynxman]

Thanks to all for the responses. Just to clarify, I do know that if I stay at a Park with 50 Amp service I will have no issues running all 3 of my A/C units plus everything else however I camp out with a group of friends (6-12 rigs) at 3 or 4 parks every year for a week to 10 days at each location which only have 30 Amp service. I have the largest with the next largest being a couple of 32 & 34 foot 5ers and the others being 24 to 26 foot trailers so all of them can survive with 30 AMP and we all enjoy the Parks we stay at because of locations and activities. I am not about to ask everyone to change because of my power issue.


Yes I can run 1 unit at a time on 30 Amp power but with 100 degree F heat and all blinds closed and the rear door closed the interior heats up at 2 degrees per hour between about 11:00 AM to 4:00 PM.When I checked the voltage drop it was at the pedestal with 2 units on but only 1 was running, the second unit was trying to start but would shut down. After that happening I stopped trying to run 2 because of the issues about damage to the motor which Ray has described. The units are all 15000 BTU so are maximum amperage draws.

I do not have the A/C units on the Inverter side of my power panel but the Inverter will supplement the power for fridge and any other supplemental devices. I have had my electric coil in the Oasis water heater off and have it set on diesel power only.



I have searched the internet for a solution and have ordered 2 Micro Air soft start units (pricey) but I viewed their installation video which showed the before and after amperage draw on a single unit (pop up trailer) and it was impressive. The soft start units are on their way and it will probably take me a week or so to get them installed. I have only 30 Amp service at home for my coach but it will give me a chance to try it out once they are installed. I only ordered 2 units because I know that is the max I will be able to run on 30 Amp if they do work as advertised and on 50 Amp power it really doesn't matter.


We are back at home now (sticks and bricks) and the next trip will be in mid August to a 30 Amp Park so I plan to be prepared if it gets warm there.


Cheers,
Hugh

[Lynxman]

Sorry for the late update but I self installed the 2 soft start kits, first one took about 40 minutes and the second one took about 15. Ran the “learning” phase for both by starting each separately 5 times with a 15 minute delay between each start sequence. Weather at home with my 30 amp service wasn’t hot but was able to run the front 2 units for 30 minutes with no blown breakers. Got to our campground this week with 30 amp service and it was sunny and warm yesterday (around 80 F) so I turned on the front 2 a/c units and we went out for about 2 hours. Came back to a cool coach so it seems that the soft starts make a difference. I’m really glad this works out!

[Lynxman]

Should also add that my fully electric fridge and my single electric coil for the Oasis water heater were both on as well although there was likely no draw from the Oasis during the 2 hours we were away.

[Domo]

Always suspect campground power first.

I would suspect the 30 amp power going into the RV is being dragged down by every other RV in the park that are trying to cool off their units in this hot weather.

I'm 30 amps running a single air conditioner and almost anything else can sometimes lead to its shutting off.