A/C will not run on generator.

The A/C runs fine on shore power.  The heat pump works fine on gen or sp.  But the A/C will not run on gen.

Am I doing something wrong?  Again, I checked the manuals and followed the instructions and looked in the library....  is this another duh moment?

Thanks,
Rob
2005 Bounder 38N

robthreedee said:

The A/C runs fine on shore power.  The heat pump works fine on gen or sp.  But the A/C will not run on gen.

Am I doing something wrong?  Again, I checked the manuals and followed the instructions and looked in the library....  is this another duh moment?

Thanks,
Rob
2005 Bounder 38N

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Kind of hard to answer without knowing what size genset your using and what size aircon you are trying to run....

What kind & size of generator do you have?

Just  guess.. but there are TWO circuit brekers on the genertor.. Make sure one has not tripped.

Those puppies will trip for the fun of it by the way, No overload needed (Vibrtion from the generator does it)

Are the A/C and heat pump the same unit?  Does the A/C fan run on generator, just not cool?  Need more details to help troubleshoot this.

sorry about that....here's the info.

7.5KW Onan Diesel generator

2 13,500 BTU A/C?s with Heat Pump.

I thunked about the breakers and checked them both (under the bed), then I thought if it was the breakers, it wouldn't run under sp either....  and the heat pumps would also be affected.

I tried letting the gen run about 15 m with the ac off to make sure the gen was nice and warmed up and there was no pressure on the ac's...  buat alas, no ac. 

Weird huh?  This isn't a major issue, but I have to go to Texas in August and really probably should have the ac's working whilst moving on down the road...

That's a strange one.  The A/C and heat pump doesn't know where the power is coming from, shore or generator.  The thermostat and controller runs on 12VDC so isn't affected by the AC power.

No fan, or just no cooling?

Ned said:

That's a strange one.  The A/C and heat pump doesn't know where the power is coming from, shore or generator.  The thermostat and controller runs on 12VDC so isn't affected by the AC power.

No fan, or just no cooling?

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No fan either....  Should I try standing on on one foot , holding my breath, grabbing one ear while reciting a FIFA soccer chant?

I would check all other 120 volt devices and see if anything else is not working on generator power....you might have lost one leg.

robthreedee said:

No fan either....  Should I try standing on on one foot , holding my breath, grabbing one ear while reciting a FIFA soccer chant?

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That's as good a technique as any

When on generator power, are any other A/C appliances non-functional?  If so, that might point to the transfer switch as the culprit.

Water Dog said:

I would check all other 120 volt devices and see if anything else is not working on generator power....you might have lost one leg.

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I did.  The TV and vcr and dvd player all worked, as did the heat pump and microwave.  All worked fine on the generator.   

Have you checked the Voltage and Frequency from the Genny. 

Do your A/Cs have Heat Strips???

What I find puzzling is the fact that you say the HP portion of the A/C works on Genny.  The HP\ running says the Compressor is starting and if the compressor starts for the HP then it should start for A/C.  If The A/C has Heat Strips that may be what your feeling rather than the HP.

Do you hear the Compressor start in HP mode????

weewun said:

Have you checked the Voltage and Frequency from the Genny. 

Do your A/Cs have Heat Strips???

What I find puzzling is the fact that you say the HP portion of the A/C works on Genny.  The HP\ running says the Compressor is starting and if the compressor starts for the HP then it should start for A/C.  If The A/C has Heat Strips that may be what your feeling rather than the HP.

Do you hear the Compressor start in HP mode????

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Yes, I heard the compressor in HP mode...great heat almost immediatly..same with the AC on shore power... 

I'm pretty sure I'm setting the thermostat right....because I got it to work on the shore power....  It was chilly today...would that have anything to do with it?  Is the ac so sensative that if the air outside is t0o cool it won't start?  It was warm in the MH, despite the chill in the air.

I been reading and reading and can't find where to even begin to exercise this gremlin....

Your HP is better than mine.  When I turn on the HP, I will first hear the ciulating fan and then hear the compressor kick in, it will take several minutes for the circulating air to get warm (HP's are not very efficient).  If I want instant heat I use the Furnace.

An HP will take as long to get warm as it takes it to get cold air from the A/C. 

Operation of either the HP or A/C is dependent upon the Tempeature of the sensor and and not the outside air with the exception of condenser freeze.

weewun said:

Your HP is better than mine.  When I turn on the HP, I will first hear the ciulating fan and then hear the compressor kick in, it will take several minutes for the circulating air to get warm (HP's are not very efficient).  If I want instant heat I use the Furnace.

An HP will take as long to get warm as it takes it to get cold air from the A/C. 

Operation of either the HP or A/C is dependent upon the Tempeature of the sensor and and not the outside air with the exception of condenser freeze.

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That's what I thought....  kinda silly to think otherwise..i know,,

The heat pump is the a/c, and the a/c is the heat pump. It's the same compressor running in a different mode, moving heat in or out of the RV.  So if one mode works, the other should too. Of course, there are electrical relays involved to change the direction in which the heat is being transferred, but you say it works ok on shore power?  The a/c doesn't know generator from shore power - it's just 120v electric.

May I suggest a very controlled test to be sure of the symptoms?  You should be able to get the a/c running on shore power, then set the t-stat high enough so it cycles off. Then start the generator, which will override shore power. Turn the t-stat back down several degrees and see if the a/c comes on. If it does not, shift to heating mode and see if that mode comes on. If it does not, there is a power problem to the roof unit, e.g. no 120v output to the circuit breaker for the heat pump & a/c unit. If it does come on, we will have to analyze the generator power output with electrical meters (frequency, voltage and amps) to figure out what is different about it vs shore power. It maybe that voltage or frequency is off enough that some electrical device simply isn't responding. If you don't have access to this sort of equipment or have the skills to do it, it will be time for professional help.

You said you checked the breakers UNDER THE BED.  Ok, I knew those were OK for the very reason you suggested (If they were tripped shore power would not run it either)

Did you check the breakers ON THE GENERATOR ITSELF?

That's suspect #1 in these cases

Suspect # 2 or 3  is a screw loose
Suspect # 3 or 4 is a screw loose (Wire connection)

What is the optional suspect #2.. Some rigs (30 amp shore cord, 50 amp generator) have  a "Front/Rear" switch, in one position the rear A/C (normally) will not work on Generator.

You have just one  single Heat pump, or one AC and one heat pump?

Probably you meat to say : the cooling of Heat pump is working, but the heating of heat pump is NOT working?

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth?"

After trying everything I could think of, and all the suggestions by you nice people, I thought that after eliminating everything as a problem..especially since everything runs on everything else, including the heat on generator..there could only be one answer.  Procedure.

So I started over and made sure I did everything correct.  I started the generator and let it run for 15 minutes.  Then I turned the AC on and sat down with a good book.  About six minutes later the AC came on good as ever.  The ONLY conclusion was that when I had this problem, I didn't leave the AC on long enough to cycle through and get going.  To test this theory I did the same thing with shore power (after letting it sit for a day) and the same thing happened....turned it on and waited and a few minutes and I had AC.

Thanks for all the input...I'd chaulk this up as another "duh" moment, but as that I am not an RV expert or AC expert or generator expert, and I read EVERYTHING I could....I think I should let this one ride smoothly on the learning curve.

Thanks,
Rob

There is a built in delay on the air conditioner/heat pump that allows the high pressure side to unload before starting the compressor.  This is to prevent damage to the compressor.