heater
Fleet Mechanic
Joined: Jan 2011
Posts: 1,709
Likes: 4
From: 8600 ft in Colo
The function switch is the **** you trun to select floor, vent, or defrost. On the back of that is a multi-line vacuum connector. The black line is the vacuum supply line coming from intake vacuum on a gas engine, or the vacuum pump on a diesel.
Senior User
Joined: Nov 2007
Posts: 435
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From: Los Angeles, CA
There is a small vacuum powered valve that directs the air to and from the defroster. The line to it breaks down over time.
The valve is located near the passenger hood hinge, by the heater core, on top of the heater air box.
The line to it is a hard, white plastic tube. That tube has a high mortality rate.
Replace the tube with a few inches of rubber vacuum hose and you'll be fine.
My computer is disconnected, so I can't send a picture. Search the forum for "white vacuum" and you will see many entries and photos.
The valve is located near the passenger hood hinge, by the heater core, on top of the heater air box.
The line to it is a hard, white plastic tube. That tube has a high mortality rate.
Replace the tube with a few inches of rubber vacuum hose and you'll be fine.
My computer is disconnected, so I can't send a picture. Search the forum for "white vacuum" and you will see many entries and photos.
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