Heater Control Valve
Thread Starter
Advanced
Joined: Sep 2008
Posts: 55
Likes: 1
Heater Control Valve
My 86 Vette has a heater control valve in the lower line going to or coming form the heater core. The upper heater core line has a line that T's off and goes to the intake. Two questions; When does the valve operate and what's the purpose of the line going to the intake. I read somewhere that the valve only closes when the AC is on so as to bypass the heater core. The valve appears to be electrically operated but everything I've read and on other cars I've worked on it's been vacuum operated.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Two questions; When does the valve operate and what's the purpose of the line going to the intake. I read somewhere that the valve only closes when the AC is on so as to bypass the heater core. The valve appears to be electrically operated but everything I've read and on other cars I've worked on it's been vacuum operated.
and IIRC is intended to prevent heat bleed from the heater core when the A/C is on by stopping coolant flow through core
Like to rear of intake is air/ steam bleed from rear of heads
Thread Starter
Advanced
Joined: Sep 2008
Posts: 55
Likes: 1
Thanks. Still trying to learn my way around the Factory Shop Manual for answers. If a description was in there, I couldn't find it. The bleed line hose to the intake has a small leak at one of the connections. Replacing it is pretty straight forward but I was curious as to its purpose.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Allows use of reg heater hose; not OEM with the nipple.
Port for tube @ intake takes 1/8" NPT plug IIRC
Thread Starter
Advanced
Joined: Sep 2008
Posts: 55
Likes: 1
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
GM engineers obviously thought there was a requirement for it
Many of the aftermarket TPI replacement intakes don't have provision for it
( or even the rear coolant passage it connects to)
and there is no mention of guys overheating engines with those intakes
Mine has been gone 8 years ( stock TPI )
Many of the aftermarket TPI replacement intakes don't have provision for it
( or even the rear coolant passage it connects to)
and there is no mention of guys overheating engines with those intakes
Mine has been gone 8 years ( stock TPI )
