I was driving home the other day and and my electric fans quit working and the truck temp got to up to 220. I got the electric fans to work again but now the truck doesnt want to warm up. Going down hill it actually cools down. I know the electric fans are not running until 190. I clean the IAT sensor and checked the themostat and it is fine. I cant figure out why it won't warm up now.

 

I know you mentioned that your thermostat is fine, but when my truck wouldn't warm up my thermostat was bad. I got it fixed real quick because driving around like that killed my fuel mileage. Goodluck

 

Sounds like a thermostat or bad temp sender.

 

you might have a air bubble in the coolant system. have you tried to burp it?

 

There is no air bubble in the coolant system.

 

It was either the t-stat or coolant sensor but I am leaning toward the coolant sensor becuase milage never went down.