'72 heater control valve???

[Tom L.]

It seems that for a few years corvettes did not come with heater control valves, I know that for 1972 there was not. a few questions???

1. Was there a reason for removing this feature from the car for this short time period?
2. Can a valve from an earlier or later year somehow be retro-fitted into the system so that cockpit temperature can be somewhat lowered during summertime cruzing?
3. Are there any ill effects in doing what is suggested in question 2?

As always, thanks for the help in advance!

[Michael W.]

Re: '72 heater control valve???

1. Cost. Only A/C cars got them in those years
2. Yes they can be retrofitted but a discreetly mounted manual shut off valve is much simpler.
3. No.

[Tom L.]

Re: '72 heater control valve???

In your reply, "cost" was a part of your answer. We all know that if the word "Corvette is used, COST goes along with it!!!

Anyway, My car is an a/c car but does not have it nor does it show one in the AIM. Was this a dealer option?

[Dick W.]

Re: '72 heater control valve???

No '72's came with one, but you can use one from a '71 by hooking the vacuum up to it as shown in the '71 service manual.

[Jack H.]

Re: '72 heater control valve???

The hot water shut-off valve was a 'marginal' feature and its discontinuance in '72 was most likely a cost saving consideration. The '71 C60 option of the AIM lists a 'truth table' for vacuum routing showing the valve was vac actuated when the system was either OFF or in an A/C mode.

That means, the heater core was allowed hot coolant when the system was in one of the various heating modes OR when the engine was shut down and vac blead off...

The last is significant because when you'd make a short stop (get fuel, eat lunch, go into the store on an errand), vac leak down would allow the valve to open and coolant would re-charge the heater core via thermal conduction/convection.

To get heat out of the heater core, you have to teach yourself a driving habit... After a short stop, run the A/C in 'MAX' mode for a few miles on the road to extract heat from the heater core again.

What others have said (install a manual, in-line, hot water valve) IS the best and cheapest 'fix'...