I just had a brand new (not reman) Denso compressor installed in my car but started out blowing cold then as I drove the 45 minutes home from the shop I noticed it alternating from warm to cold then finally a few miles from house completely warm almost hot. I'm taking it back first thing in the morning. Just wanted everyone's thoughts before he tries to make up something stupid. He said he did flush the system and fully charged with Freon.

 

Likely he either didn't tighten the lines going to the compressor or there's a leak in the system he didn't catch.

What led him to replace the compressor?

 

A good while back my compressor completely locked up, so I'm just now able to afford to get it replaced. Hopefully its something that simple and he honestly fixes it.

 

Improper refrigerant charge. If it works fine when cold then starts acting up when the car heats up, it's probably overcharged and cycling off the high pressure switch. Let the car cool off then try it again.

 

That, or look into this... DIY: No Heat? Repair the Heater Control

 

Yep most likely overcharged with freon. Thats when it'll start cycling from warm to cold air.