I've got a 99 suburban k1500. The A/C stopped working about 6 months after I bought it and I just left. Now it's about a year later and I recharge the refrigerant only to find out (after 3 cans) that while the front is now blowing cold but when my transmission shifts roughly when I run the A/C.

I tried driving around with only 2 cans in the system and the the A/C clutch not fully engaging, or staying engaged, and I had no shifting problems. Now that the clutch stays engaged, my truck bucks with each shift, up or down. If I turn the A/C off, not a single problem.

I can personally live with out the A/C and just drive around with the windows down, my kids on the other hand, feel differently.

 

When the A/C compressor is engaged it puts more of a load on the engine. That is probably why the rough shifting.

 

Yea, so suspect vacuum leak on the intake, idle speed control solenoid, throttle position sensor, bad alternator bearing, power steering switch or belt tensioner or serp. belt may be at fault.

 

Would a missing clip on the air filter cover cause an intake vacuum leak? If it's anymore than that it'll have to wait. Two days after I posted the question I blew a brake line in my driveway and it cost me $500+ to have the lines and the front brakes and rotors replaced.