I just checked the Air Conditioner Diagnostic codes on the LCD display.

I'm getting a

E0 76 (Heater Supply Unit Circulation pup (A31m1) over load
E0 77 (Heater Supply Unit Circulation pup (A31m1) over load

E0 91 A/C cmpressor ground Activation, open or short circuit.

This is the 1st time I've ever checked codes on my A/C. Since I was unsure what codes might have been "old", I cleared all codes and will recheck codes again later tonight.

What is the Heater supply unit circulation pup?

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML