Heater problem

JOHNUW93

MEMBER
FORD TEMPO

1987 Tempo with 2.3 liter. Mileage is 78K on the odometer, but I don't know if it's rolled over.

The problem is that the heater blows hot and cold. I have replaced the heater core, water pump, fan control switch (on thermostat housing) and thermostat at various points. Changing the core did improve things - before, it was always lukewarm at best, now blows hot and then usually rapidly cools when driving. Seems to warm up from time to time, then blow cool again for a while, etc. I checked the fluid in the radiator cold - full up. Water pump belt seems tight, and was recently replaced.

Changing the heater core, I inspected the ducts and doors. They move properly. Some of the foam seal on the doors is missing.

I installed an aftermarket thermostat. Is it possible that it is opening and closing at the wrong temps?

I have not replaced the radiator. The car does not overheat.

4 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

If it rapidly cools when driving, the radiator is likely fine. The t-stat does sound a little suspicious.

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Friday, February 2nd, 2007 AT 9:22 PM

TAURUSWHEEL

MECHANIC
718 POSTS

Did you replace the water pump belt od r the water pump? Or both? It's possible the blades on the pump are worn to the point where they'll keep the engine at the right temp, but can't supply the heater core. Never had these issues with water pumps years ago, another example of re-engineering, very common today.