I've run heaters in the summer when I had a car on the verge of boiling over in traffic. With it off.. there's not much added cooling advantage as the moving air takes heat away from the heater core. Bob
About all it does is get you a extra 6ft of circulation. However in near boiling situations, turning the heater fan on full MAY help bring down the temp, at the cost of an even hotter car interior. BILL
Any old Chevy I saw didn't have one, however they may have been present on cars with factory AC. The heater boxes were pretty well insulated so the passive heat never got into the passenger area. Bob
I had a trip in the summer of 1991 with my 1982 Chevy wagon... it was very hot out and we were stuck in traffic outside of Delaware on I95. Having the heater on was the only thing that saved up.. although the wife was not pleased. Bob
If you're going to try to cool your engine a bit, you need to have the blower running. There's very little heat rejection over the heater core with no airflow. Just prepare to sweat your butt off!
^^^^ agreed with them! Saved my but once while overheating, but it sweated me out of the cabin- must have windows down and fan on high to make that heat go somewhere! No fan=just a tad more fluid to circulate which wont help much at all. -rick.
I was maybe 150 miles from home, but it was getting dark and cooler. Great on July 3rd and 90* out with 95% humidity, a pissed off wife and sweltering 2.5 year old... Bob