AC not working on generator.

Billt · 06-07-2019, 08:22 PM

My air conditioning unit works great when I am connected to 30amp service. However when I switch over to my generator it will turn on for about two minutes and shut down. I cannot even get the fan to work. I reset the breaker and nothing changed. I could not even get the fan to turn on. I made sure that there were no other power drains.
Ideas?

armullis59 · 06-08-2019, 05:21 AM

Check your generator for two circuit breakers that might be present on the generator. If either one is tripped, reset it. Each breaker is for the two legs of your 50 amp service in the coach (if you have 50 amp service).

Billt · 06-08-2019, 08:15 AM

My rig is 30amp. All outlets work. Just not AC

BobC · 06-08-2019, 08:51 AM

You mentioned re-setting the breaker. Are you doing this just to be sure everything is OK or is it tripping?

Billt · 06-08-2019, 10:11 AM

Just to be sure.

BobC · 06-08-2019, 07:03 PM

Have you checked the voltage coming from your generator with a multimeter? If it's low, the A/C is going to draw more amps than normal which could cause your power management system to shut it down. You say the outlets work but did you test the voltage at them with a multimeter? If you just plugged something in, like a lamp, to test, low voltage wouldn't necessarily be a problem. Your generator should be putting out 112V - 125V (no load) according to the following:

https://www.partsfortechs.com/asapca...20RV's.pdf

If it had anything to do with your thermostat or A/C itself, it wouldn't run on shore power.

Billt · 06-10-2019, 08:08 PM

Checked the voltage at the generator plug. Read 121.
Hooked up my EMS on generator plug. It didn’t detect any errors.
AC still not working.
Any other ideas?

BobC · 06-10-2019, 09:10 PM

Did it ever work on generator power or is this something new?

1. I've been dealing with some transfer switch issues, which I know you don't have, but many of the threads I've been reading cite problems relating to loose connections. I suggest opening the generator outlet box and tighten all the connections (really tight). A loose connection could supply enough current for your outlets but not the A/C. Do the same where the wires from the outlet box connect to the generator and its breaker. There may or may not be signs of burning or other damage.

2. It's also possible that your generator just isn't putting out the amps it's supposed to be putting out. If this is the case you might also have problems running your microwave at full power. The generator breaker could also be faulty, breaking down but not "tripping" at higher current loads, or it could be something more complicated, but let's check the simpler things first.

Note that your EMS wouldn't necessarily detect any of these issues since it's only checking voltage and polarity, not current handling capability. Note that current, contrary to voltage can only be measured under a load.

The nice thing about not having transfer switch is that, since everything is fine on shore power, your problem has to be somewhere in the generator outlet box, the wires from it to the generator, the generator's breaker or in the generator itself. You know you're OK from the shore power plug to the A/C.

Your generator manual should have a troubleshooting section that may help.

BobC · 06-11-2019, 08:50 AM

Quote:

Originally Posted by BobC

Note that your EMS wouldn't necessarily detect any of these issues since it's only checking voltage and polarity, not current handling capability. Note that current, contrary to voltage can only be measured under a load.

i missed the fact that the EMS also checks frequency.

Billt · 06-11-2019, 02:10 PM

Thanks Bob, I’ll check the connections.

BobC · 06-13-2019, 07:35 AM

There's another, similar thread on this topic:
http://www.winnieowners.com/forums/f...er-354659.html

al1florida · 06-13-2019, 01:13 PM

Quote:

Originally Posted by Billt

Checked the voltage at the generator plug. Read 121.
Hooked up my EMS on generator plug. It didn’t detect any errors.
AC still not working.
Any other ideas?

Stick your meter in any of your AC outlets and monitor the voltage while running the A/C when the generator is supplying power.

The voltage will probably drop a volt when the fan comes on and then you will see a good sized voltage drop when the compressor starts, but it should quickly come back up to within 4-7 volts of the generator no load voltage.

If the voltage doesn't come up a lot of the earlier suggestions (loose connection, etc) need to be checked.

If you can, do the above voltage checking when on shore power first. This way you have a bench mark of a working system to compare to.

elcriollo · 06-16-2019, 09:14 PM

I had the same problem. In my case I discovered the power control unit would not allow the ac to run until the generator runs for a few minutes. All other outlets worked in the meantime.
I was told by the power control tech that this is the way it is programmed in order to protect ac unit from damage due to a sudden voltage drop until the generator reaches proper operating temperature.

Upinsmoke · 06-17-2019, 02:31 AM

Hi all. Thankfully not having any major issues at the moment (always a blessing) but did want to ask/clarify a couple of things.

I had always assumed that the ATS was the box inside the external electrical compartment into which the 50 a. power cord terminates. I had never checked to whether that's where the audible click comes from when plugging into shore power. Do you believe this is the ATS? I saw a picture in one of the posts here that made it look like maybe it was a separate switch/box located in a "utility" compartment. Thoughts?

Also, along the same line, when I hook into shore power the ATS switches automatically right away. However, when I start/run the generator, the amount of time between the generator starting to run, and the lights on the panel lighting up indicating there is usable power appears to be increasing. I recently timed it and it was 2minutes and 30 seconds! Does that reasonable or within normal limits?

Thanks

fkempf216 · 06-17-2019, 07:51 AM

You problem is not the generator if your getting A/C power with your genset running to all your outlets. Does your AC unit start and run every time you turn on the AC unit then shut back off? You might have a bad thermostat. to check it you need to test the power going to the AC unit through the Yellow wire going from the thermostat and AC unit to see if it's losing the 12 volts after it runs for the two minutes you stated. If you are losing the 12 volts on the yellow wire then the thermostat is probably bad or has a low voltage lose to the red 12 volt feed wire. If you have more then one Yellow wire check directly behind the thermostat for wire's colored Red, Green, Yellow, Blue and white or black. The blue wire should be you common wire, the red is a constant 12 Volts, the yellow wire feeds 12 volts to the compressor relay in the A/C unit, the green wire is for the fan relay (if it's a single speed fan) the white or black is for the heat pump if you have one. Test all the colors to the common blue wire. If all the thermostat wires check out OK then you need to check the circuit board mounted in the A/C unit for damages or bad connections.

Lakejumper · 06-17-2019, 08:47 AM

Upinsmoke, that’s about how long mine takes. It varies on whether I just ran the generator or not.

fkempf216 · 06-18-2019, 04:48 AM

Billt, Is your MH equipped with a "Energy Management System" ? If you let the geset run for more then five minutes does the A/C units come back on and run normally? If so that's normal. My 2015 Itasca Sunova 35G used to do the same thing till I installed a delay start in both the A/C units to prevent the compressor from starting and shutting down while the Energy Management system when through it's system testing. Now my A/C fans come on for a few seconds and shut off till the E.M.S. finishes and turns on the fans again and the timers I installed on the compressors time runs down for the compressors to start.