I have a 1991 Volvo 740 Turbo with an AC/blower problem. The air quits whenever I step on the gas pedal and comes back on after the pedal is released. The temp is fine - just that air problem. Any ideas on what causes this and will it cause an arm and a leg to fix if I take it to a mechanic. Thank you very much for your help.
First impression is a vacuum issue, a leak somewhere in the system if it’s vacuum operated. On a car this age it could be anywhere from the vacuum motors at each blend door to hoses or connections, and multiple leaks possible as well.
I agree with ken as to the likely problem. The cost to fix it really depends on how hard it is to get to. I have no idea how accessible it is in a 91 Volvo.
There is a vacuum reservoir under the hood that has a check valve in it that is there to prevent this very problem. Check it for a leak somewhere or broken connection.
What everyone wrote may be true. You are hamstringing us a little with your description. What exactly do you mean by “air quits”. Do you hear the blower stop? Check to see if the air output moves from the dash outlets to the defroster when you put step on the accel pedal.