WORKING ON ROOF A/C it runs and is cold for about 15 to 20 minutes and then it trips the 20amp breaker that it is connected to. trailer breaker box. I was thinking possibly I should use a 30 amp breaker. Do you have any suggestions

Could be a weak breaker. The head pressure may be high. Is the inlet filter clean?

Weak breakers will trip when at or near full capacity. Replacing it with a 30A breaker is dangerous. You then have no protection of the undersized wiring with the resulting possability of fire. 20A is really borderline for a AC unit, especially if it a 15K AC unit. Replace the breaker with the same size then refrain from using the AC on 20A.

Low voltage will cause the AC to draw more current, what size power cord are you using to feed it and how long is it?Next I would see what the current draw rating is on the AC unit. If you up the circuit breaker to 30 amps you may be pulling 30 amps through wires that are only rated for 20 amps. Not a good idea.

thank you all for your info. The power cord is 25ft. plugged into 30amp at rv parkthis trailer in 30amp. I cleaned the filters and gently the fins checked the wiring and connections. I turn on the a/c and it takes right off and blows cold air for 15 min. then trips the inside breaker 20amp that is a/c only. I will go test the volts to see if they are 109 or better by the way the main is 30/15 is this adequate

Possibly a "poor" starting capacitor. On the initial start, the system pressure is likely low / lower and allows the unit to start within the current rating. Probably after a bit, the A/C has cycled off and then attempts to restart. The increase in "head pressure" potentially causes an increase in current required tripping the breaker. Just a guess... as others suggest, try replacing the breaker and see if things change and go from there.

roof A/C TRIPS 20 AMP BREAKER | Good Sam Community

13 Replies

rbpru
Explorer II
Jul 25, 2015
Low voltage will cause the AC to draw more current, what size power cord are you using to feed it and how long is it?

Next I would see what the current draw rating is on the AC unit.

If you up the circuit breaker to 30 amps you may be pulling 30 amps through wires that are only rated for 20 amps. Not a good idea.
donn0128
Explorer II
Jul 25, 2015
Weak breakers will trip when at or near full capacity. Replacing it with a 30A breaker is dangerous. You then have no protection of the undersized wiring with the resulting possability of fire. 20A is really borderline for a AC unit, especially if it a 15K AC unit. Replace the breaker with the same size then refrain from using the AC on 20A.
Bigbird65
Explorer
Jul 25, 2015
Could be a weak breaker. The head pressure may be high. Is the inlet filter clean?

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roof A/C TRIPS 20 AMP BREAKER

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