A/C keeps tripping from noon till dusk

A dirty condenser lessens the ability to condense hot gas discharge to a liquid which increases the load on the compressor and electrical system. A dirty evaporator does not effectively expand the entering liquid refrigerant, therefore reducing the load on the compressor. A dirty evaporator is not good, but has nothing to do with the breaker tripping.

if its a Dometic Brisk Air it may be that the tiny screw inside the thermostat is set too high. I explained all this on the other air conditioning thread nearby. the A/C repair guys I've talked to didn't even know it was there.

Glad to hear it :B

Update- The problem has been fixed!! Low voltage during peak heat time was causing the A/c breaker to trip. We installed the Hughes Autoformer and it fixed the problem but also installed a Dometic hard start kit and replaced the inside breaker for good measure. The Rv is now nice and cool in Texas heat. Thanks everyone!

Freon pressure and compressor load definitely increase with temperature.
Dirty condenser or evaporator will increase effective temperature and compressor load.
Yes low voltage can be an issue too.
Amp draw over max rating indicates the sealed compressor motor is failing. (assuming correct voltage and clean coils)

Ivans21 wrote:
Just to clarify things a bit, it’s the 20amp A/C breaker inside the rv that’s tripping. We’re connected to 50amp shore power with a Surge protector and 50to30 amp cable.

That's even more of an indication it's low voltage. An AC compressor load remains about the same but as voltage goes down, the motor will draw more current as it tries to maintain enough HP to drive the compressor (power = volts x amps). And if the 20 amp breaker is drawing close to it's rating, the bi-metal element that trips a breaker can warm up enough to trip more quickly, esp. if it's adjacent to the 30 amp main breaker (in your panel) that is running high current. (UL has a standard that limits how hot various parts of a breaker can be.)

That's my take on it anyway. The 20 amp breakers protecting AC units don't trip very often. If it were the 30 amp breaker in a pedestal that was tripping lot, I'd say it's almost sure to be that breaker. The pedestal breakers can be in abominable condition and sometimes it's a wonder they work at all. They're subjected to seasonal temp. and humidity changes that they never see in buildings plus they get switched on/off a lot and they don't have a switching duty rating.

The breakers in RV panels are on the cramped side and have the converter in the same enclosure which contribute to more heat that the breakers are subjected to. And when the inside of an RV is like 90F and higher in the summer, the breakers can't adequately dissipate the heat generated inside the converter/panel enclosure (being plastic won't help either). Breakers *should* be able to carry their current rating indefinitely and this article has a bit of info. on the effect of heat on them.

Note that the lower the voltage gets, the lower the current draw is for resistive appliances like hair dryers, toasters, coffee makers, electrical griddles, electric HWH, electric fridge element, etc. The output of these (in watts) drops as the square of the voltage. At 104 volts (the point at which a PI EMS will cut out), you're only getting 75% of the appliance's 120 volt rating.

Dennis12 wrote:
myredracer I think that they are talking about the shore breaker. ???. And it is still possible that the breaker in the unit is bad or weak.

Yes the shore breaker.
What I have done is manually flip flop from one outlet/breaker to the other before things heat up and trip. Repeat as needed till things cool down.

Even if it's not the cause, I would replace that breaker. They don't like tripping a lot. It can make them weak so they will trip at lower current. One sign that it's weak is if you feel warmth when you touch it.

Just to clarify things a bit, it’s the 20amp A/C breaker inside the rv that’s tripping. We’re connected to 50amp shore power with a Surge protector and 50to30 amp cable.

I just picked up a Digital multimeter from my local store and will be testing voltage later today. Thanks for the tip about the Autoformer, it really seems like a good investment.