A/C on shore power trips breaker after 30 minustes

[wpatters1229]

2006 Four Winds top side A/C works fine when running off the generator but when on shore power it only stays on for about 30 minutes and then trips the 20amp breaker. Have cleaned all the coils etc. Could this be a bad breaker?

[time2roll]

Really need a volt reading in the RV and a clamp-on ammeter to do some actual diagnostics.

Although at least verify the fridge and water are off or set to propane only. If the battery was low that converter will also draw significant power for 30 to 60 minutes.

[wpatters1229]

I like to solve problems and this one is bugging me. I have a generator for power outages and it has a 30 amp output on it. I may just fire that up and hook up the shore power cable to it and see if it will keep the A/C going. I have a feeling that 20amps service is not enough even though it should be.

[bobndot]

Ext cord going to 30 amp adaptor is too light.

You can get away with a 20 amp cord but it has to heavy enough gauge wire. 10-12 ga.


Or , Use the rv’s 30 amp cord direct to a 30 amp socket or use that 30 amp cord thru a 20 amp adaptor if you don't have a 30 amp socket at your home.

[wolfe10]

wolfe10 wrote:

wpatters1229 wrote:
What could be the difference between shore power and generator power?

Could be VOLTAGE.

What is voltage on that 20 amp shore power with extension cord with the A/C running?

Do you have an ATS? If so, have you checked that the connections are clean and tight and that the wires are not burned?

Please, before you go buy an extra/spare A/C, tell us what the VOLTAGE is with the A/C running!

[valhalla360]

wpatters1229 wrote:

It is just the internal breaker. The RV is in my driveway. I just replaced the extension cord (50 ft) with a heavy-duty gauge wire. I did feel the connection on the smaller cord where it connects to the adapter and it was warm. Maybe that smaller wire created too much load along with the A/C. Nothing else is running. The 30-amp breaker is for the whole RV. The rest of the breakers are all 15 amp. I have not tried the A/C with the larger cord. I think that may have been the problem along with the 99-degree heat here in CA. I am about to go turn on the A/C with the heavier cord to see if that was the problem. It takes about 20 minutes before the breaker trips.

When you say "heavy duty" is it a full blown 30amp RV cord or one of the orange extension cords. Even a good quaulity orange one is typically smaller gauge wire than a 30amp cord.

Also, how long is the total cordage. If you are stringing together 100+ft of cords, that's generally not good for running heavy loads.

This comes into play as smaller gauge wire and longer wiring rund will result in votage drop. When this happens, you get higher amperage and that can heat up the wiring which further reduces the voltage...if it's on the edge of popping, something like the battery charger kicking on may push it over the edge even though you didn't see or do anything.

If you have a multimeter, you should check the voltage at one of the RV outlets while the aircon is running. Ideally, it should be up around 120v. 110v or higher is OK. Down to 108v is marginal but technically in spec. Below that and you start to risk burning up the aircon compressor motor.

If you don't have a multimeter, you can pick up a voltage meter that just plugs into a wall socket. We have one that we leave always plugged in. When we set up at a new site, we typically take a look to see that the voltage is reasonable. Also, when we kick on the aircon, we check as it can pull the voltage down bye 4-5volts if the park power isn't strong.

[wpatters1229]

OK, I started the A/C and it did the same thing. I am going on a month-long trip to Montana so I will see if a dedicated 30 amp in a RV park will work. I also ordered a backup portable A/C unit to keep me from frying. Worst case I can run the generator but that seems too disruptive for other RVers. I am thinking that I may not have ever run the A/C at home except to put a load on the generator to maintain the generator each month.

[wpatters1229]

valhalla360 wrote:
Where are you looking at the breakers (pedestal or internal panel)?
- If the pedestal, you should be plugging into the 30amp outlet. A 20amp might work but it's marginal. It's not separate for the microwave.
- If it's the internal breaker panel (inside the RV), the 30amp should be the main breaker that kills power to all the other breakers. They often don't do a good job of labeling.

Are you trying to run the microwave at the same time as the air/con? If yes, there's your likely problem.

Easy way to check if it's the microwave breaker is to flip it off. If the clock on the microwave goes off you found the microwave breaker.

What is the voltage arriving at the RV? It's relatively common for park voltage to sag during peak demand on hot summer weekends. As voltage goes down, amperage goes up to compensate. Especially if the aircon breaker is getting weak, this could be enough to pop it. (The generator is only servicing your RV, so voltage should hold up fairly well).

It is just the internal breaker. The RV is in my driveway. I just replaced the extension cord (50 ft) with a heavy-duty gauge wire. I did feel the connection on the smaller cord where it connects to the adapter and it was warm. Maybe that smaller wire created too much load along with the A/C. Nothing else is running. The 30-amp breaker is for the whole RV. The rest of the breakers are all 15 amp. I have not tried the A/C with the larger cord. I think that may have been the problem along with the 99-degree heat here in CA. I am about to go turn on the A/C with the heavier cord to see if that was the problem. It takes about 20 minutes before the breaker trips.

[wolfe10]

wpatters1229 wrote:
What could be the difference between shore power and generator power?

Could be VOLTAGE.

What is voltage on that 20 amp shore power with extension cord with the A/C running?

Do you have an ATS? If so, have you checked that the connections are clean and tight and that the wires are not burned?

[wpatters1229]

One other thing. I have an extension cord going to a 20 amp wall socket that hooks up to my 30 amp cord using an adapter. It has never been a problem. Especially since the load is less than 20 amps. Still confuses me how my generator puts out the same AC 120 volts to the same circuits and the AC runs as long as needed. What could be the difference between shore power and generator power?

[valhalla360]

Where are you looking at the breakers (pedestal or internal panel)?
- If the pedestal, you should be plugging into the 30amp outlet. A 20amp might work but it's marginal. It's not separate for the microwave.
- If it's the internal breaker panel (inside the RV), the 30amp should be the main breaker that kills power to all the other breakers. They often don't do a good job of labeling.

Are you trying to run the microwave at the same time as the air/con? If yes, there's your likely problem.

Easy way to check if it's the microwave breaker is to flip it off. If the clock on the microwave goes off you found the microwave breaker.

What is the voltage arriving at the RV? It's relatively common for park voltage to sag during peak demand on hot summer weekends. As voltage goes down, amperage goes up to compensate. Especially if the aircon breaker is getting weak, this could be enough to pop it. (The generator is only servicing your RV, so voltage should hold up fairly well).

[wpatters1229]

I just looked at the circuit breaker and the one that trips is 20 amp and next to it is a 30 amp breaker. The tags on the power door say the 30 amp should be for the A/C and the 20 Amp for the Microwave. Maybe that is the problem? What is weird is we have never changed anything with the electrical panel and have had this unit since 2010. Could it have really been wired wrong and now decides to fail? Does the Microwave only need 20 amps?