A/C's quit working

[ggourlay]

1999 32' Holiday Rambler 30amp 2 Duo-therm A/C units. Plugged into 30amp service camping for 3 days alternating front & rear A/C all fine. 3rd day A/C units quit working. All other 120v appl. still fine. No breakers tripped.
While at home a day later tried running A/C's again, both worked (alternately) for a short time but soon quit working again. No problems leading up to this 2nd trip requiring A/C running all day. Have tried all troubleshooting I know of, any suggestions?

 

[Kirk]

Re: A/C's quit working

Greg,
To do any real trouble shooting, first a few questions that may help.

First of all, do you have a 30A or a 50A RV system? Does your RV have one of the power management systems to alternate the two A/C units or were you doing this by hand in some manner?

If you let it rest, will it once more repeat the problem with them working for a short time, then fail?

As a guess, I am suspicious that you do have a power management system that does the alternating of the two units. If I am correct, try leaving one A/C turned off and run just one to see what happens. If the one you try first should stay on line for an hour or two, then shut it down and try the same with the other unit.

Have you measured voltage inside of the RV at all? If voltage is low, alternating current motors will draw a higher than normal current and that will slowly cause them to over heat. Most of those motors have an over temp. device to protect the motor from just this type problem and it will open, and then eventually re-close when temperatures return to near ambient. If your interior voltage falls much below 108V there is a chance that this could be the problem. If the voltage inside the RV, with the air operating is less than that, say down around 100V or less, then the likely-hood of this is much greater.

Let us know what you can and this may help.

 

[ggourlay]

Re: A/C's quit working

Hey Kirk, Thank you so much 4 ur time!

1. 30amp rv
2. NO power mgmt system (1 unit at a time off 30amp or both if gen. is running)
3. After rest it WILL work temp. & repeat & fail

I am baffled a bit because for a week over the 4rth of july while plugged in I ran the A/C ALL WEEK without a hitch & the 1st 3 days of this trip the A/C worked perfectly up until the last day
when the failure 1st occurred.
The ONLY other power concern up until now is the fact that my battery charger/power converter cooling FAN will not engage & the unit gets quite hot. When I asked the dealer that sold me the RV about this they said it was normal & that the fan would eventually engage when it got hot enough. (still hasn't engaged).?????
Don't know what to check from here.
Thanks,
Greg

 

[Pillaz]

Re: A/C's quit working

An overheating converter can pull more power and cause what Kirk is talking about. What other a/c current appliances are you running at the same time as the a/c. You may be maxing out your 30amp service and causeing low voltage to your a/c units. The other thing to check is your a/c filters and fins. If they are clogged it will over work the fan and overheat the condensor.
Just a thought. Good Luck and let us know how you made out.
Oh, one other thing. Was the ambient temp very hot and humid? This will make your a/c work much harder.

 

[Kirk]

Re: A/C's quit working

I really don't see much chance that the converter is having any effect on the air conditioners. The converter draws current, depending upon what the state of your coach battery is and any other 12V demand. The only thing that is associated with the air conditioner which uses 12V power is the thermostat. If it were to loose power that would cause the a/c to shut down, but I seriously doubt that is a factor. If you want to make sure, nearly all converters are connected to the 120V power via an outlet plug so just pull that plug to isolate it from the system. If it should happen to be hard wired, open the circuit breaker that supplies it and you will know that it isn't a part of the problem.

Do you have a good digital multi-meter that you can check the voltage to the RV with? It should be no less than 108V and no more than 132V with the ideal being 120V. That voltage should not drop more than 5V when the a/c is running from what it is when not operating. It may dip more when the compressor first starts but it should come back up to near what it was without the load. A soft power line might cause your problem.

You also need to know what is happening when the a/c units stop working. Have they lost power (as I suspect) or is there some other problem with them? As an electrician, I find it strange that both react the same way, when you are selecting them manually. Do you turn off one and then turn on the other? Do you always allow the one you turn off, to sit for at least five minutes after running before starting it again? They need several minutes for the compressor pressure to bleed off.

Have you tried just letting one a/c run to see if it will operate continuously to see what happens or if there is a problem? In all RVs that I have seen there is a separate circuit breaker for each a/c unit which also means that there is separate wires from the distribution panel to each one. Unless the problem is some issue with the power it's self, it is hard for me to see why both would fail at the same time. But in order to know, voltage readings are important.

 

[Guest]

Re: A/C's quit working

I agree with Kirk on this ,, also i'm gonna thow in some stuff too ,,, ck u'r plug real close and make sure u don't have a burnt prong ,,, also ck the pedistal ,, they may have dropped something on their side ,, like a loose wire on the recptacle ,, but just a few other options to consider :approve:

 

[dugnmarn]

RE: A/C's quit working

Is the trailer perfectly level? I once had a problem with the A/C not working well when the trailer wasn't level. Also, what is the relative humidity in your area. The A/C units I have experience with work better in dryer conditions (ie. Arizona). In humid conditions, they struggle to keep up.

DUG