Vacuum Lines
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From: South Australia
Vacuum Lines
Have 2 pipes one larger than the other coming from firewall on American passenger side. Can anybody tell me what part they play in the hvac system
1988 Iroc Z TPI
Thanks
Gary
1988 Iroc Z TPI
Thanks
Gary
Joined: Sep 2005
Posts: 28,036
Likes: 2,502
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Vacuum Lines
If you're talking about vacuum lines:
One brings vacuum in from the reservoir system, which is fed off of the manifold; it goes to the little vacuum switch thing on the control head, which then sends it to the various doors that control airflow. One door selects between defrost and everything else; another selects the everything else flow to the floor, the dash vents, or a mix of the 2; a 3rd selects the blower motor's intake between cabin air (recirculate), and outside air (normal).
The other goes to the heater control valve. Just like the vacuum doors, the control head controls whether coolant flows in the heater core. There's a vacuum operated valve that performs this action.
They used to be color-coded; one was "white" (really more of a light greige kind of shade), the other purple. "White" is the supply, and purple the HCV, if memory serves.
If you're talking about 2 tubing connections that are about 5/8" and ¾" dia, those carry coolant to the heater core. The smaller is the hot water inlet, the larger is the return to the "cold" or suction side of the cooling system.
One brings vacuum in from the reservoir system, which is fed off of the manifold; it goes to the little vacuum switch thing on the control head, which then sends it to the various doors that control airflow. One door selects between defrost and everything else; another selects the everything else flow to the floor, the dash vents, or a mix of the 2; a 3rd selects the blower motor's intake between cabin air (recirculate), and outside air (normal).
The other goes to the heater control valve. Just like the vacuum doors, the control head controls whether coolant flows in the heater core. There's a vacuum operated valve that performs this action.
They used to be color-coded; one was "white" (really more of a light greige kind of shade), the other purple. "White" is the supply, and purple the HCV, if memory serves.
If you're talking about 2 tubing connections that are about 5/8" and ¾" dia, those carry coolant to the heater core. The smaller is the hot water inlet, the larger is the return to the "cold" or suction side of the cooling system.
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