Heater core shutoff valve?
Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,392
Likes: 218
From: Merritt Island, FL
Heater core shutoff valve?
My recent A/C issues have gotten me wondering about hot water flow through the heater core, which in these cars (my ZR-1, and I think all LT1/LT4 cars) occurs regardless of A/C setting, from what I can tell. It seems like having 200+ degree coolant in the heater box, when trying to deliver cold air just inches away, is counterproductive and likely to reduce ultimate cabin cooling capacity. I know there's the blend door, which closes fully when the Temp is set to "60", but I would assume there's still some heat being radiated through that door and perhaps through the plastic heater box housing into the underdash space and into the cabin.
Has anyone installed a valve to block off coolant flow into the heater core in the summer months? Or does someone have a reason why this would be a bad idea? Or am I just making something out of nothing?
Has anyone installed a valve to block off coolant flow into the heater core in the summer months? Or does someone have a reason why this would be a bad idea? Or am I just making something out of nothing?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
The early cars like my '87 had a vac operated valve that physically isolated the heater core when A/c engaged.
When my valve went out , I just installed a manual valve on one of the heater lines to serve the same purpose.
Turn on in winter ; off in summer
When my valve went out , I just installed a manual valve on one of the heater lines to serve the same purpose.
Turn on in winter ; off in summer
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
With hot coolant passing full time through the core , you are reliant on the blend door to seal correctly and prevent the passage of air across the heater core.
Every pre '90 blend door I have pulled out has the edge seals in bad cond so stopping coolant flow to the core can only be off a benefit
Every pre '90 blend door I have pulled out has the edge seals in bad cond so stopping coolant flow to the core can only be off a benefit
