Pontiac Repair: A/c shudder, mass air flow sensor, mass air flow

Question
When I turn on the a/c (occassionally) the car shudders.
Turn off a/c  - car is OK.
Do you think it is the compressor or freon low??
2003 suburban 5.3L 70K miles.
thanks

Answer
Hey Foster

it can be a few things The compressor can be bad starting to seize up and putting a load on the engine but I doubt it If that were the case the belt would start slipping and making noise. It may be an issue that the extra load on the engine is making the engine run bad.m I would check the basic stuff like a plugged fuel filter or air filter. That's a long shot but you never know. It could have a MASS air flow sensor that's acting up and not seeing the extra load on the engine when the compressor is on. if you have any kind of aftermarket cold intake kit on this those air filter contaminate the mass air flow sensor all the time I'd look at that. Any service engine soon lamp on? You could have an issue with a plugged "lean" injector and the extra load on the engine make it run worse. Usually it' cylinders 7 and 8 that plug up due to the orientation in the fuel rails the dirt winds up in the rear cylinder injectors.
Good luck :)