1968 Vent and AC Issue

[Paul B.]

As a new member, I recently purchased a 1968 Corvette with AC. I have found that hot air is entering the car when the ventilation controls are set in either AC or Vent modes. The hot air reduces the effectiveness of the AC. I spoke to a mechanic at the local Chevrolet dealer who works on Corvettes and he says that there is nothing that can be done to fix the problem. Just wanted to know if others have encountered this problem and if there are any fixes. Thanks!

[Bob D.]

Re: 1968 Vent and AC Issue

Paul

Welcome to the NCRS. I have a '71 A/C car and I don't get hot air when the ventilation controls are set in the AC mode. I do get some hot air when the vent mode is in operation, but that depends on the ambient temp. Have you checked the vacuum valves under the dash and the vacuum controls on the thumb wheel in the console. The thumb wheel which adjusts your modes has a bunch of vacuum lines attached. It could be one of the vacuum controls or valves is not operating properly. Hopefully some other folks with more experience than I will check in.

Bob

[Jeffrey S.]

Re: 1968 Vent and AC Issue

Paul,
WELCOME! I would look at the water shut off valve which is located mounted to the inner fender on the passenger side on A/C cars. Its function is keep hot coolant out of the heater core area when the A/C is on. It is vacuum operated from the heater/A/C control head on the console. If this is not operating, hot coolant gets to the heater core and when you select heat or A/C the air around the core is heated and gets into the cabin. Just a guess.
Jeff

[Paul B.]

Re: 1968 Vent and AC Issue

Jeff, Thanks for your advice. I will check on the shut-off valve.

[Paul B.]

Re: 1968 Vent and AC Issue

Hi Bob, Thanks so much for your prompt response. I'll need to follow-up on this. PJB

[Jim T.]

Re: 1968 Vent and AC Issue

Paul the hot water shut off valve on my 1970 only works when the dial is on MAX air. The setting on MAX sir sends vacuum to the vacuum operated hot water valve to shut off engine coolant from moving through the heater core. My 1968 does not have factory air conditioning like my 1970, so I can only speculate that your 1968 factory air Corvette functions the same.