Well my f150 302 heat gauge was say it was getting to hot. Now it will get up to opp. Temp, then drop down to cold and stay there. Drove an hour to work today and it hardly came off cold. I don't have as much heat as I should but I think that maybe a blender door issue not for sure though. The temp gage has been fluctuating from too hot to not hot enough. But I think that might be a temperature sending unit issue. I bought a new unit but I can't find where it's at on the engine. It is a single wired unit but I can't figure out where it's at on the engine the guy autozone tried to show me where he thought it might be but I don't take a lot of faith in what he said. he showed me that it look like it was underneath the air compressor on the driver side towards the front. It is the unit for the gage. Tell me that my thermostat might be stuck open is a brand new thermostat so I don't see how to be stuck open is there a way I can test it to see if it's stuck open. Thanks for all your help this is a great forum I've learned a lot.

 

Thermostats are cheap and every time I buy one I buy 4 and i have had 3 of them be bad...I check them in water on the stove with a gauge...

Sounds like you might have a bad one....

blender door can be an issue and you should hear it change when you work the controls...

the temp sensor is the Single wire sender on the Intake manifold...

 

Please be more specific where at on the intake what side uper, bottom I need layman's terms

 

Lower part of the intake manifold drivers side front.... single wire sensor...when you unplug it the gauge wont work...thats how you'll know

 

I'd say bad tstat too...I've had many a bad ones. You may have to love yer harness to see the sender.