Hello All From A Newbie,
Anybody out there know anything about how the heating system works on our Marquis? I have a problem with my '79 and I just don't know enough about it to fix it. I have diagnosed it at least part of the way..........
After checking everything out, the problem appears to be in the vacuum motor that operates the hot air door under the dash. All the controls seem to operate fine and select all the proper operations. Here's the problem. The vacuum motor that moves the hot air door does operate except from what I can tell, it moves the air door all the way to the closed position and wont adjust to the open position to allow the hot air into the cabin. If I disconnect the vacuum line going to the vacuum door motor, the door goes back to the rest position and allows the hot air into the cabin. I checked the vacuum line while it was disconnected and found that as you moved the temp control, it changed the amount of vacuum at the hose which is I'm assuming how it regulates how far the air door motor moves. However, when it is hooked backed up to the air door motor, it moves the motor all the way closed and won't adjust it. Can anyone help me? Once in a while it works as normal but usually not. I can't tell what would cause this. Obviously not a bad vacuum motor since it does operate and it doesn't appear to have a vacuum leak anywhere. It's almost as if it has too much vacuum and overcomes the spring in the air door motor.
Thanks in advance for any ideas guys.
Sincerely,
Stuart D.
Portland, OR
Anybody out there know anything about how the heating system works on our Marquis? I have a problem with my '79 and I just don't know enough about it to fix it. I have diagnosed it at least part of the way..........
After checking everything out, the problem appears to be in the vacuum motor that operates the hot air door under the dash. All the controls seem to operate fine and select all the proper operations. Here's the problem. The vacuum motor that moves the hot air door does operate except from what I can tell, it moves the air door all the way to the closed position and wont adjust to the open position to allow the hot air into the cabin. If I disconnect the vacuum line going to the vacuum door motor, the door goes back to the rest position and allows the hot air into the cabin. I checked the vacuum line while it was disconnected and found that as you moved the temp control, it changed the amount of vacuum at the hose which is I'm assuming how it regulates how far the air door motor moves. However, when it is hooked backed up to the air door motor, it moves the motor all the way closed and won't adjust it. Can anyone help me? Once in a while it works as normal but usually not. I can't tell what would cause this. Obviously not a bad vacuum motor since it does operate and it doesn't appear to have a vacuum leak anywhere. It's almost as if it has too much vacuum and overcomes the spring in the air door motor.
Thanks in advance for any ideas guys.
Sincerely,
Stuart D.
Portland, OR
, 
, All options except dual exhaust. Currently looking for 2 front seats: Heated, Memory, and Light Graphite color!!
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