A/C works fine on generator but not on shore power

[Rubikon]

2001 Bounder 33R
30 amp service
Manages power between 2 a/c units via a climate control module

Sorry to join the forums and immediately start asking for help but I am in a bind. I have some family in town for the 4th that are staying in our motorhome. We have a small rv park in our community that we are using. Earlier in the day I took the vehicle to the rv campsite and hooked it up to shore power. Everything was working fine including the A/C. A short while ago we took them out to the RV and the A/C was not blowing.

I checked the breakers, fuses, shore connection (including trying the 50 amp connection using a 30 to 50 amp adapter). Everything seemed fine. Everything else in the motorhome is working fine including the fridge, hot water heater, and lights..... etc.

I started the generator and everything works fine.... INCLUDING the A/C. So the problem has to have something to do with shore power only which tells me the A/C units themselves are working fine. I recently purchased a climate control module thinking it had gone out but was fine. Since I had the spare module I hooked that up and no change. So I don't think that is bad.

Any ideas? Keep in mind it was working fine a few hours earlier when we left it. The problem also only exists on shore power.

Any help is greatly appreciated.

Thanks,

Shane

[Rubikon]

Well to follow up I fixed the problem. The post for the spot we were in was apparently not providing the proper amps. We moved spots this morning and everything is fine. Wierd that it was fine for a couple of hours before the problem occured.

The maintenance guy said their line shorted which in turn burned out my plug. Once I fixed the plug and moved spots everything was good.

Thanks for the help on this.

[OnaQuest]

About the only possibility (given the symptoms you have) is the small transfer switch used to power the front air conditioner from either shore power or generator.

It appears that the normally closed contacts on this switch are not making good contact. Take a look at the diagram attached and you will see that the front air conditioner gets it's power through the small TX/switch, from the main breaker, when on shore power, but directly from the generator via the tx/switch when gen is running.

This TX/switch is usually located near the main circuit breaker panel. Possibly near that control unit that you replaced. It may be necessary to remove some paneling or covers to find it. A good sharp rap with small mallet will usually free it up.

The transfer switch shown in the upper left is your normal power transfer switch. The transfer switch being discussed here is the one in the middle of the page. Air Cond. unit #2 is usually the front unit in your rig.

If each of your air units are fed from their own individual circuit breaker, then the problem could possibly be in the path from the breaker to the small TX/SW. Check the tightness of the screws on the breaker feeding that unit. (including the white return wire for that circuit)

[wa8yxm]

First if you have an electric water heater. TURN IT OFF, likewise the do not use the microwave (use Propane to heat water)

The Energy Management system may be shedding the AC units.

in a dual A/C 30 amp rig there is, somewhere a switch.. It is usually a 3 way (Front/Rear/Both) and must be set properly.. Front one works, Rear the other works Both the manager takes over.

Generator overrides this

NOTE: one of the circuit breakers on the generator may feed the REAR A/C. both when using generator AND when using shore power. If this breaker is tripped the rear A/C will not work.

note also that Onan breakers do not have a "Tripped" position, it's on and off, if it trips it moves all the way to off. (in many cases)

[Rubikon]

I am in East Texas. The temps right now are unseasonably cool. I will try hooking to a different post today to see if that helps. Thank you for the replies. It seemed like an odd problem but makes more sense now.

[dougrainer]

You need to look at the Climate Control system module. WHAT was the reason you replaced it? I think you have a built in EMS system and it KNOWS that you are on 30 amp and is shedding the AC unit. That is why it works on APU. Doug

[MiPaJacks]

Voltage really sags in this heat.
Add a Progressive EMS to your system to protect against low voltage. Call Randy at Best Converters

[dahkota]

Up here, during the heat of the summer when the temperature hits 100+ degrees and the humidity is godawful, we have 'brown outs.' They usually occur between 4 and 7 pm when people are getting home from work and cutting on the a/c and other appliances. The first time it happened at home, I thought our a/c died. At work, they were kind enough to warn us so we didn't lose data. The power companies didn't announce it; they just throttled power so the grid wouldn't overload. I'm not sure if the power companies in Texas are allowed to do it, but this could possibly be a cause of your problem.

[2oldman]

Check the voltage at the CG post, and, if possible, when the a/c is running. It's common for campground power to sag when many people are running air.