Heat Consistancy Issues

[Chambers]

Hi all, lately when I'm commuting I will get heat on and off, sometimes its hot enough that you have to turn it down, and others its blowing ice cold air. I know having a little air in the system can cause these symptoms, but in the manner I am having troubles and when they occur lead me to believe it to be a different problem.

Today, when driving I had the windows down and I turned on the heat, but it was a very dull heat, I could barely feel it compared to the temp of the outside air. Then all the heat sopped and it blew ice cold air, but it wont stay at the same fan speed when it does that, I had it in Hi, and it went to a higher speed, such as when you turn the AC on, it will blow a larger volume of air out. It does the same thing when the heat goes out. I then put the windows up, and the heat came back. ??? I have no idea on why this is, lol. It's quite comical. If I put the windows down, the heat goes away again, lol.

On occasion when I'm driving and I have heat, really good heat, I will go to turn the temp down and as soon as the temp leaves 85 and goes to 84 the heat stops, and the larger volume of air will start pumping out again, with cold air. Then the other occasions it will work just fine, the temp will gradually go down degree by degree.

All of this has lead me to electrical issues, but I don't know where to start, I know the climate control will have to come out and be inspected but I wouldn't know what to do when I get it all apart, such as which resistor needs to be replaced etc... I plan to take the car off the road and take the dash out to re-wire the starter solenoid, so I will be able to inspect the wires for the heater system. Any help on where to start would be great. Thanks.

[mkiiisupra]

stab in the dark here, but if it acts funny when you roll down windows maybe has something to do with the temperature sensor?

[Chambers]

Is that located near the passenger side air duct? Thanks.

[mkiiisupra]

yes, i think its that little square blue plastic bit

well blue in my car anyhow lol

[Chambers]

Ok, thanks, I will be sure to check that out when I have every thing apart.

[ddmcse]

sounds like the classic heater vsv to me

toyota Supra pictures heater issue

value works off vacuum ,

no vacuum, no value going up and down = no heat

[Chambers]

Ahh that makes sense, thanks for the link but I don't quite like the idea of the heat being dependent on my pedal, I will see about it if I cant fix it other wise. Today I had heat for almost my entire commute, the last five minutes the heat went out again, so I'm still leaning towards electrical, but I could be the valve. Thanks.

[mkiiisupra]

i rerouted my vac lines on mine awhile back so it is always open when the car is on.

[supramacist]

Hello Chambers.

I don't know why no one has said this yet.

Heater core. Heater core. Heater core.

Those are classic symptoms of a shot heater core dude.

[Chambers]

Well dam, would there be any way of telling if the core is bad if I had it out, or is one of those things you hope is bad and spend $$$ on replacing it? lol.

I will have the dash out and have access to the core when I get a more suitable daily driver, my trucks get horrible fuel millage.

Thanks!