Lenox A/C repair question - Blown circuit breaker

I have a Lenox A/C, about 12 years old. - when the a/c compressor running it trips the 30 amp circuit breaker when it recycles. It starts from a cold start ok, but after it has been running a while, it will trip the breaker. Any suggestions. - I know I'll have to call a technician but I would like to have a idea of what it could be.

thanks

The cheapest thing it could be is a bad circuit breaker. For $10 you could find out...

When the compressor runs, on one side the pressure goes up to maybe 250 psi and the other side it goes down to maybe 20 psi - no surprise. When the compressor is off, the compressed refrigerant continues to flow through the system until the pressure is equal on both sides of the compressor. A compressor likely can't start against a large pressure difference. When the compressor can't start it draws a high current and trips the breaker (or an internal overload unit). This behavior is normal (including, for example, refrigerators) when the system tries to restart too soon. There should be enough time delay built into the thermostat to prevent short cycling from happening.

You might want to time how long the system runs and now long it is off.

-- bud--

Bud, - thanks for the explanation, I had a tesh service it and they found it to be over charged. Some valve was installed the wrong way, he corrected it and it works fine.