Just had the PCV valve, the intake plenum gasket and the valve cover gaskets replaced. Ever since this repair everytime I turn the heater on the car surges and the rpm's run from high to low from high to low from high to low when the compressor is engaged. The compressor is engaged in the following heater positions: floor, floor and face, floor and defrost, defrost.

Do you think that this problem might have something to do with the PCV valve hose not fully connected?

I don't find it normal that the compressor would become engaged when the heater is turned on to floor or floor & face positions. None of my past cars have done this and even the mechanic found it quite odd.

Thank you for your time.
Dominique