1989 Supra heater system

[whocando]

Hi,

Just bought a 7M-GTE 1989 supra and the heater is not working (ie. it blows but there's not heat).

Can anyone give me an idea what the heater system looks like.

I can't find this in any manuals I have. I know where the water starts out the engine but from there on what happens?

Am I looking at a heat exchange or what?

Regards

[banana_socks]

Don't have experience with a Supra in particular, but I've worked on a few Toyotas of that era and they're all very similar. There should be two reasonable sized hoses running through the firewall, inlet and outlet. Inside the cabin is a small heat exchanger. There should also be a heater tap on the inlet hose, generally mounted on the firewall just before it goes through.
When the temperature control is on hot, the heater tap is open and all the interior air is passed through the heat exchanger. When its on cold, the tap stops coolant flowing through the interior circuit, and the interior air is diverted past the heat exchanger.

If you're getting no heat, its likely to be one of three things: heater tap stuck closed, interior air diversion stuck closed, or coolant completely rerouted. Be warned as sometimes if the heater core starts leaking ppl will just eliminate the heater circuit.

[whocando]

Thanks banana_socks,

Does the heater slide on the dash have any resistance?

Is it cable or electronic?

[banana_socks]

I'd be pretty confident the heater slide will be cable driven. My 1991 Corolla was completely cable driven. My 1990 MR2 has the vents controlled electronically, but the heater slide itself is still cable driven. They can get sticky with age, but there shouldn't be anything restricting its movement.

[whocando]

No there's not any restriction. It's very easy to slide. That's why I thought it was electronic. It's too easy for cable.

[crowncustom]

Supra temp control is electronic.The tap is on the passenger side on the firewall.Hose comes from the top of the head to the tap.Drivers side it comes out of the firewall to a steel pipe just behind the head.Also check to see if its running a thermostat.This is for a NA 7M Supra but GTE should be the same.
Cheers Brett.

[Daddio]

Your Supra has a vacuum driven heater valve...its as said, on the fire wall passenger side. There is an electronic solenoid which contrls vaccum (driven off the heater control panel)
To test try running vacuum direct to the heater valve (ie bypass the solenoid) If it doesnt work then, the vacuum bit is fubar...get a new one. If it does work, then the culprit is likely the VSV, again get a new one to fix it...

MkIII heater valves are a bit hit n miss...if you get stuck, pm me, I think I have a spare one somewhere....