2010 Durastar AC Issue

Sounds like a classic case of a failing electric motor. Motor drags, draws more current, trips the breaker. Replace the blower motor.

 

Change the 20A breaker to a 30A. Rule of thumb is not to have more than 65% load on a circuit, and that system is pushing between 18-21, so more than likely that's the problem. Also check the terminals, they should not be lose, they need to be tight and that could cause some heat. I've also seen the ground lose on the linear power module, and that can cause similar problems.

 

Blower motor runs a 30 amp breaker. If the breaker is hot the breaker is either no good, or the terminals it plugs into is loose and causing a bad connection which is causing the heat. This is one problem. If the a/c works after a key cycle, you likely have a problem with the pressure sensor or circuit. Once the system detects a pressure problem, it will shut down the ac until the next key cycle. Check the pressure sensor connector for any corrosion. The high pressure sensor can be changed without evacuating the system.