A/C Heater Control Vacuum Switch or...
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Drifting
Joined: Feb 2005
Posts: 1,583
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From: Richardson Tx.
A/C Heater Control Vacuum Switch or...
The '79 will not blow any air out of the dash vents (Max, Norm or Vent), nor the top (defrost) vent as well. It will only blow air down the floor vents. The recirculate door also does not open on the pass. side kick panel when the A/C switch is set to Norm. I removed the A/C Heater Control Vacuum Switch and performed the well known procedure of taking it apart and applying di-electric grease to it. I put it back together but there is no change to the air flow. I verified that there is vacuum on the black line (vacuum source line) coming into the back of the a/c switch (at the rubber vacuum line junction)- not strong, but detectable vacuum.
To test the actuator that controls the air flow to the vents, I used a hand held yacuum pump , removed the rubber vacuum junction, and put my hose connection into the hole whose line (black with Tan) goes to that actuator. With the A/C on I pumped away and if I continued for a few seconds the air would start coming out of the dash vents as designed. As soon as I stopped pumping the air would return to the floor vents.
Trying to figure out of the problem is:
1) A/C Heater Control Vacuum Switch still leaking
2) Not enough vacuum flowing to open the actuator (how much should there be?)
3) Faulty Actuator (hope not - its real hard to get to)
thanks!
To test the actuator that controls the air flow to the vents, I used a hand held yacuum pump , removed the rubber vacuum junction, and put my hose connection into the hole whose line (black with Tan) goes to that actuator. With the A/C on I pumped away and if I continued for a few seconds the air would start coming out of the dash vents as designed. As soon as I stopped pumping the air would return to the floor vents.
Trying to figure out of the problem is:
1) A/C Heater Control Vacuum Switch still leaking
2) Not enough vacuum flowing to open the actuator (how much should there be?)
3) Faulty Actuator (hope not - its real hard to get to)
thanks!
