1997 GMC Safari "heater vacuum leak" Questions

heater hoses back to the engine. Sometimes, a vacuum line could have a break causing there to be no vacuum to operate the valve. Also it should be noted that if this is your first winter with this car

...airconditioner works as well the heater but will not blow out the front vents or anywhere else? Sounds like a vacuum leak. Check the vac supply on the intake manifold. Passenger side front of

heater on - vacuum sucks to open valve. and before that make sure fuse is ok . for rear AC mine does not work either and it is leak on pipes that go from front to rear .. 10 feet of pipes and tubing $

...vacuum TO the ac/heater climate control switch in the dash? Have been looking for a vacuum leak. Found one in the engine compartment at the throttle body but no others in the engine bay. Van still ...

...Heater core must be vacuum leak tested before it is remove from vehicle if a heater core leak is suspected. Drain engine coolant. Remove instrument panel. For 5.4L (4V), if quipped, remove junction ...

...is blowing, I would guess an issue with your heater control module or a vacuum problem of not supplying vacuum to move the plenum door. Hope that helps. not a vacume leak properly a heater core ...

...or to the defroster. A leak in the tubing, ball, or motor can cause the door(s) to retract to default if vacuum drops down as it does at idle. Have the heater box and vacuum system to it checked

...vacuum leak in the heater controls. When you select heat, vacuum is directed to a vacuum motor. This motor operates a vacuum actuator that moves a linkage that moves a door inside the heater box to ...

...vacuum pump is on the passenger side of the car about half way back - front to back of the engine. What you describe sounds like the heater valve. It is used to shut off coolant flow to the heater ...

...heater control vacuum harness, or anything connected to it. Commonly disturbed by stereo installation Could also cause a rough idle. Leak could also be found between manifold and vacuum junction to ...