My 2003 Grand Marquis check engine light on. Temp gauge stuck on cold. Blowers working but not at full force. Not overheating so I'm thinking thermostat stuck open or a sensor problem?
I appreciate any input..

 

You got it. Its one of the two. With the engine cold, go for a drive for 3 or 4 miles and and then feel the upper radiator hose or radiator inlet. It should be hot enough so you can't hold your hand on it very long. If its only warm or cool, I would change the thermostat. I'm assuming you have checked to see that the system is full of coolant.

 

Thanks bulldozer, I'll check it out

 

Blowers working but not at full force. Not overheating so I'm thinking thermostat stuck open or a sensor problem..

 

I took it to the FORD store, they replaced the thermostat and all is well with the world. Thanks guys for your help. This is a great forum/