Can turning on your heater take heat off of your car engine?

[Noel_Prosequi]

@Una Persson

But I said this in my post:

which means that if the thermostat is wide open - meaning that you’re already above the closing/regulating temperature. Or are we talking about something else here that’s not clear?

Nope, you’ve pinned my issue. What wasn’t clear to me was whether your experiment on your own car was done in such a way as to ensure no thermostat effect. You’ve clarified my question. Thanks.

[gotpasswords]

@Telemark

Car Talk had a puzzler once about some AMC car from the 60’s IIRC that had a switch on dash labeled “desert”. It would vent the heat outside the car rather then into the cabin, acting as an additional radiator for hot weather use. I assume cooling systems were less efficient then and it made more of a difference.

Ah, so that’s what that setting was for! We had an AMC Ambassador wagon with a “Desert Only” setting. As for efficiency, the beast had a 380 V8 (At least I think that’s what the badge was on the air cleaner) with police package (in a station wagon??) and it did have its share of overheating problems.

[Gorsnak]

In cold weather (I’m talking -40 here) cranking the heater all the way up would drop the coolant temperature in my old diesel Rabbit to the point where the gauge would be full left. This was partly because I never got around to sticking cardboard in front of the main rad, as we folk up here are wont to do in winter. Nevertheless, it’s an illustration of the principle.

[susan]

I had several Corollas and Tercels in the 80’s and 90’s that responded quite nicely to having the heat up, especially when I was driving in the mountains.

[Kent_Clark]

It happened to me on my Plymouth Colt wagon when I was stuck in traffic one particularly hot summer day. As the temperature needle climbed closer to the red, I cranked the heat up full, and could see the needle come back down.

For point of comparison, the needle came down a lot faster after I got out of the traffic jam and was able to drive at a reasonable speed.

[kanicbird]

Car Talk had a puzzler once about some AMC car from the 60’s IIRC that had a switch on dash labeled “desert”.

I thought that desert setting was so the a/c compressor ran continously, instead of cyclying, this is becasue the low humidity meant no icing of the evaporator.

[Telemark]

@kanicbird

I thought that desert setting was so the a/c compressor ran continously, instead of cyclying, this is becasue the low humidity meant no icing of the evaporator.

According to Car Talk (I never owned one of those cars) it was to vent directly to the outside through vents in the front quarter panels.

[racer72]

@MC$E

I have an 87 Corvette with a heater control valve, and I’m pretty sure I’ve seen one on other newer vehicles also. Even with a valve, most of the cooling you would get comes from the heater fan pulling in cool(er) outside air and passing it over the heater core. Without that fan on, the area around the heater will warm up to the temperature of the coolant and stay there.

I have in front of me a 2001 Stant catalog. There is no listing for any heater control valve for the 87 Vette, the last year listed in 1981. The latest for most other GM cars is 1972. I also checked with 3 large auto parts retailers (Schucks, Auto Zone, and NAPA) none lists a heater control valve as a replacement part for your car. If your car has one, someone else added it. When I attended auto technician school back in 1984, we were told then heater control valves were a thing of the past.

[MC_E]

@racer72

I have in front of me a 2001 Stant catalog. There is no listing for any heater control valve for the 87 Vette, the last year listed in 1981. The latest for most other GM cars is 1972. I also checked with 3 large auto parts retailers (Schucks, Auto Zone, and NAPA) none lists a heater control valve as a replacement part for your car. If your car has one, someone else added it. When I attended auto technician school back in 1984, we were told then heater control valves were a thing of the past.

Sorry, I guess Stant doesn’t make the part. It’s probably a dealer only item. Thanks for playing.
http://www.corvettepartsman.com/index.asp?PageAction=VIEWPROD&ProdID=2849

[Gary_T]

@racer72

When I attended auto technician school back in 1984, we were told then heater control valves were a thing of the past.

I’m sorry you were told that, because it absolutely wasn’t true. Perhaps your source had tunnel vision, only familiar with certain makes of cars and erroneously thinking what was true of those was true of all cars. But regardless, lots of popular vehicles made in the last twenty years do indeed have heater control valves.

[jimbeam]

I used to have an 83 olds cutlass that I had to get by that way once, it worked too.

[psychloan]

I agree - turning on the heat can make a big difference in the right situation. I had a Volvo 240 back in the 80s that had a tendency to overheat if I got stuck in traffic. Turning the heat on full blast would bring the engine temp back down to a reasonable level.

[Johnny_L.A]

@jimbeam

It damn sure worked on my '65 Ford pickup. No doubt about it.

It worked in my '66 MGB in the desert, and in stop-and-go traffic in L.A.

@Telemark

Car Talk had a puzzler once about some AMC car from the 60’s IIRC that had a switch on dash labeled “desert”. It would vent the heat outside the car rather then into the cabin…

Heh. I had the same idea, thinking I should have a lever that vented the heater to the outside. Never followed through on it though.

[Uncommon_Sense]

@Gary T

I’m sorry you were told that, because it absolutely wasn’t true. Perhaps your source had tunnel vision, only familiar with certain makes of cars and erroneously thinking what was true of those was true of all cars. But regardless, lots of popular vehicles made in the last twenty years do indeed have heater control valves.

I’m pretty sure my 96 Explorer has a heater control valve, since I had to replace it when it sprung a leak!