AC short cycles on 30 AMP

[ksucats]

Picking up my Landmark from repair shop tomorrow morning - they could not find the problem with our rear AC.

When running on 30 AMP (nothing else 110 v on in the coach) the AC will run for 3 to 4 minutes and then will shut off. Using an infrared thermometer I find minimal decrease in air temperature coming from the output vents versus interior air temp. After 2 minutes or so (the delay for the compressor to reduce pressure, managed from the thermostat as best I know) it will start up again, run a couple of minutes and then quit again. This cycle repeats - we had it running for over 20 minutes at home and it never stopped cycling. The repair facility was able to duplicate this but found nothing causing it according to the phone call I just got off of.

On 50 AMP (according to the repair facility) the AC runs fine and cools fine. We tried it in Huber City UT three weeks ago while hooked up to 50 AMP service. The rear AC cycled the same as if it was on 30 AMP. The repair facility states that they ran the AC for a long period and it never had a problem.

So, the question- any ideas on what may be causing the problem. I questioned the service writer who called me asking if the 'capacitor(s)' could be the problem - he simply said that the technician had spent over half a day on it testing everything. ????

Thanks.

 

[danemayer]

You have a Precision Control Circuits (PCS) energy management device that has control over the A/C units. When plugged into 30 amp service, the PCS device senses the reduced power and per its programming, sheds loads if usage exceeds 30 amps. If the A/C blower continues to run, but the compressor stops, the PCS may be triggering a shutdown of the compressor by electrically simulating a frozen coil.

You do have other 120V AC loads in the coach. The Power Converter can routinely use as much as 12 amps and peak at higher levels depending on battery condition. If your water heater is set to 120V AC electric operation, it can draw around 15 amps. When using 30 amp service, you should switch the water heater to propane/12V DC operation.

But if the A/C blower also shuts down, it may not be from the PCS.

At home, if you're on a 15 or 20 amp outlet, you need to manually set that value into the PCS or it will unsuccessfully try to manage to 30 amps.

You should also try running one of the other A/C units to see if the problem occurs on more than one unit. If not, that might signify a problem with the one that's shutting down.

You might take a look at our Electrical User Guide and the Landmark 365 User Guide in this folder.

 

[ksucats]

Dan: Thanks for your reply.

This is a dedicated 30 amp plug (I also have 50 amp but routinely use the 30 amp as the 30 amp cord is so much easier to use .) That said, this AC used to run just fine on this circuit - in fact it would run fine on my two Honda 2000s with the parallel plug. Now use a Honda 7000 and last football season I could run both the rear and center at one time. The other two ACs (center coach and the bedroom) still run fine on the 30 amp -- all individually of course. As for the rear - It does shut down completely when it stops - it is just like the unit was turned off manually. I did check the 'Energy Management Device' -- it shows nothing being abnormally ended - everything normal. Water heater is off (on our panel we have a switch for 110 and another for 12 volt - both are off; I also turned off the switch on the water heater itself just to make sure). I even turned off the inverter to the residential fridge since the fridge is also turned off right now. I'm at a loss - in my ole mind and from what I've read, it acts like one of the capacitors is not doing its job and starting the compressor (no cold air). However, the service writer says it was cooling. ????