1990 Toyota Supra Heater blowing cold air

SAVAGE_6988

MEMBER
1990 TOYOTA SUPRA
6 CYL
2WD
AUTOMATIC
135,000 MILES

I have a 1990 toyota supra with a new JDM motor. I let the car warm up and turn the heater up to 85 and on high it blows cold air so I replaced the thermostat and it did not help I looked at fuses and found nothing wrong there. Could it be my heater core something less. It does not over heat at all but the top hose to the radiator looks like staw when you hold one end could that be the problem.

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

Can you clarify the term STAW I am not familiar with that. Try this. Try warming the Vehicle, then carefully feel the heater hoses, are they both hot? If one is cooler than the other, You need to flush the core, or do a replacement job on the heater core. Also if the system has a heat control valve on the heater hose, make sure it is working! Also check the thermostat, and the temperature blend door, thats under the dash, in the heater plenum. You can flush this yourself, buy the prestone flush kit and install the tee in the heater return line. Disconnect the heater hose at the waterpump, clamp the hose in back of the tee you installed and back flush till it runs clear.20 mins or so.