Heater core?

[Ken K.]

I have a 1977. Does the hot water run in the heater core at all times? If it does, what could be wrong? What do I need to fix?

[Steven B.]

Re: Heater core?

Ken, the '77-'82 cars heater vacuum switch shuts the hot water off but there will be water in the core. When the vacuum opens the valve hot water begins circulating.Steve

[Jim T.]

Re: Heater core?

I have a 1970 Corvette with factory air conditioning. The vacuum operated valve only closes off the circulation through the heater core when MAX air is selected for air conditioning. The rest of the time there is full time circulation of engine coolant through the heater core.