AC getting amperage spike after an hour use.

sayoung wrote:
Did I not understand what breaker is tripping ? The AC is tripping only the house or genny breaker BUT not the breaker in the rv for the AC or RV main breaker ? If that's the case, I doubt it's actually an AC issue but a wireing issue such as in your shore power cord.

It is very common for a House(residential) breaker in a garage to trip instead of the RV 30 or 20 amp breaker. Remember, his 30 amp breaker genset breaker also trips and not the RV breakers. Doug

Did I not understand what breaker is tripping ? The AC is tripping only the house or genny breaker BUT not the breaker in the rv for the AC or RV main breaker ? If that's the case, I doubt it's actually an AC issue but a wireing issue such as in your shore power cord.

ouliwei wrote:
All good suggestions. I will look into each of everyone's suggestions. The AC is a Coleman Mach 3+ (13500 BTU).

Is it advisable to clamp amp meter around the extension plugging into the generator, or on one wires connected to the compressor?

BLACK compressor wire. You only want compressor amp draw. Doug

All good suggestions. I will look into each of everyone's suggestions. The AC is a Coleman Mach 3+ (13500 BTU).

Is it advisable to clamp amp meter around the extension plugging into the generator, or on one wires connected to the compressor?

When it happens, check to see if the evaporator is freezing up. Maybe the sensor has come loose?

1. Clean both the Outside condensor coil AND the inside Evap coil.
2. Now, you state nothing else on. Not correct. When you plug in a RV, you ALWAYS have the Power Converter pulling power, and other small appliances like a TV and such even if OFF.
3. You need a AMP draw on the compressor AFTER you do the cleanings. You don't state year model. THAT is crucial to what may be happening. BAD NEWS if over 5 years old. Your description is a classic bad compressor. After running for that hour, the head pressure builds up and trips the breaker. What fools some people is, WHY the Garage breaker and NOT the 20 amp AC breaker in the RV. Because of the length of 120 wiring from your house breaker system to the garage plug and then to the RV. Your tell is, the Genset breaker ALSO trips.
4. So, you need a AC amp clamp on gauge and WHEN the breaker trips, you take a amp reading when it finally restarts. The NORMAL progression of a defective Compressor is, they start out at its normal 10 to 12 amp running rating and as it runs for that hour, the amp draw slowly raises up. The compressor amp draw should STAY at its running rating(10 to 12 amps) as long as the system coils are clean. Usually when I have your type problem, I connect my amp probe and run the AC and monitor it. Usually withing 30 minutes I see the amp draw has increased showing a bad compressor. Doug

https://www.harborfreight.com/digital-clamp-meter-96308.html?utm_source=google&utm_medium=cpc&utm_campaign=19166646406&campaignid=19166646406&utm_content=147222427387&adsetid=147222427387&product=96308&store=&gclid=CjwKCAjwhdWkBhBZEiwA1ibLmGVJLTOEh5W63MvHFa02I-_QggbwsFNCGQdK5Zbf-Pdg_yyDfN8pYxoCQMMQAvD_BwE

I find the wattage demand increases the longer I run the roof air.

What is the resting voltage (shore power)?

What is the voltage under load (shore power)?

Let's kind of ignore the house connection on a 20a breaker. It has worked in the past and trips it now. The bigger issue is that it is tripping a 30amp on my brand new 4500 watt generator, and does not do it at start up. it only does it after an hour.

I will look at the coils. The coils I am able to see are all very clean. I will pull it apart and see if any might be dirty and in need of a cleaning.

When the breaker trips is there anything in the house that stops working at the same time? Common practice to wire multiple outlets and/or lights to each circuit breaker.

Roof top A/Cs are usually less than 15 amp draw.. No problem on a 20 amp breaker if they are running well and do not need a good cleanout of the condenser coils.

WAIT. SUSPECT.. What happens if the condenser is dirty (And note on most A/C's the dirty side is the side you can not see.. AirExcell (Coleman) is the only Sucker I know of.. The rest blow.. By that I mean suck/blow air through the condenser.. Suckers get dirty on the OUTSIDE where you can see it)

Normal operation.. An A/C is a heat pump.. it pumps heat from the Evaporator to the Condenser.. then a fan blows outside air over and through the condenser to carry the heat away..

Dirty Condenser: The air does not move freely and thus heat builds up. as the heat builds up.. Charles law comes into play (Dang I went to College about 1970 and I still remember it's Charles Law.. Scary).

As The heat builds Charles law says the volume of the refrigerant increses.. And because of something called the Thermal Constant of Expansion... It increases faster than the volume of the tubing and passages so the pressure goes up up up.

Now as the pressure goes up the compressor has to work harder and harder to push refrigerant through the lines... and the harder it works the more current it draws.

Now since it's taking an hour... (It's not Really Really dirty) That would take only 15-20 minutes in my case) but I would suggest you go "Up on the roof" with the tools (#2 Phillips on most rigs) to clean the thing.

You will likely have to remove the shroud (Around a dozen screws.. take a magnetic parts tray with you) and then an inner cover.. (Assorted ways they do that some are real easy (Like 6 screws easy) some are ... "Fun" (Not one bit).

Coleman.. Take a bigger Screwdriver (like A #4) in addition to the #2.. 4 Bolts lift the shroud peal the condenser replace shroud and bolts.