Heater core shutoff valve?

[VetteMed]

My recent A/C issues have gotten me wondering about hot water flow through the heater core, which in these 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?

Thanks
Andrew

[Paul Workman]

Sounds like a candidate for a science experiment to test your hypothesis!

Easy enough to run the AC with at thermometer in the air stream: 1) with the heater core in normal config, and then 2) a simple "U" bypass installed in the heater circuit. Comparing the results would be interesting - to me at least (as I love science experiments - always have;))

P.

[VetteMed]

Sounds like a candidate for a science experiment to test your hypothesis!

Easy enough to run the AC with at thermometer in the air stream: 1) with the heater core in normal config, and then 2) a simple "U" bypass installed in the heater circuit. Comparing the results would be interesting - to me at least (as I love science experiments - always have;))

P.

Paul, thanks for the reply. I think that will be the plan, to see if there's an appreciable difference. If so, I will probably try to install something semi-permanent to act as a switchable bypass.

[VetteMed]

I just got to thinking -- the heater bypass valves that are available, are 1-in, 2-out, where one of the outputs goes to the heater core, under heat demand, and when AC is needed, the other output is supposed to return coolant to the water pump or other suitable area in the cooling system return side. Trying to figure out where I'd route the bypassed coolant back to if I were to plumb in such a valve.

EDIT: Looks like 4-port valves exist, to form an "H" in the system, I think that would be the way to go here if needed..

[QB93Z]

I would suggest that you consider the effect of having stagnant coolant in the heater core. I suspect that you will eventually have issues with clogging of the heater core and possibly corrsion. You may want to have a small amount of flow to keep the heater core coolant from stagnating.

My comparison is the Throttle Body coolant cavity. That cavity has relatively stagnant coolant in it. Every throttle body plate that I have removed has had a "goopy" mess of deposited coolant in it and a lot of throttle bodies I have seen have external corrosion issues.

Jim

[-=Jeff=-]

84-87 used a heater control valve on the Heater core lines that accomplished what I think you want to do:

here is a post from CF

http://forums.*************.com/c4-tech-performance/2172122-heater-control-valve-solution-85-87-corvette.html

On thing I am unsure of is what vacuum line to use..