1998 Windstar - Temp gauge goes to bottom when heater turned on! - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

seeya205 · 10-19-2011, 20:40

I have a 1998 Windstar with 3.8L engine. I replaced the intake gasket last June and the van has run great since. Today I turned the heat on and the gauge slowly drops to the bottom. Turn heat off and it slowly comes up. Changed the thermostat twice with no change. When the heat is off, the temp stays steady all the time even on the highway. Also had an emissions test after the gaskets were replaced with great results! The heat is hot when on. Grounded the temp gauge sensor and it worked fine. What would cause this?

**Bert** · 10-19-2011, 21:16

Did you ground it when the engine was hot and the gauge was low? And unplug it and see what the gauge does?

seeya205 · 10-20-2011, 18:55

No, I grounded it cold!

**Bert** · 10-20-2011, 21:15

What did the gauge do when it was grounded? What did it do when the wire was unhooked?

seeya205 · 10-21-2011, 06:13

When I unplugged the sensor, the gauge went to the bottom. When I grounded the plug, the gauge went to the top.

**R.S.LOGAN** · 10-21-2011, 08:56

Got to be faulty sensor ? Saying that , I've had a few on other cars where removing and refitting cured the fault . It just got a better earth / ground by removing .

seeya205 · 10-21-2011, 16:37

I'll pick up a new sensor and let you know!

seeya205 · 10-27-2011, 16:22

Picked up the sensor! Put it in and still same problem! I noticed that heat does get cooler if I have the heat on for a long period of time!

**Bert** · 10-27-2011, 17:32

Sounds like the gauge and sensor are working properly. The engine evidently isn't getting hot enough. Did they give you the right thermostat? The heater core would be acting like an extra radiator to cool what heat is in the system.

**Bert** · 10-27-2011, 17:35

The thermostat is different in a 3.0 than a 3.8.