Engine temperature and heat fluctuation.

[lolapotter]

Okay: my engine temperature is fluctuating between "cold" and about halfway to "hot." In addition, my heat is working only when I'm going fast, like above 50, on the expressway, but when I stop at a light, it's cool again. The place I take my truck tells me they can't find the problem, so they're thinking it must be electrical. Three weeks ago, the same thing was happening, and finally the truck overheated because the radiator was empty. Today, when my auto repair shop looked, the coolant was a gallon low. SO, I'm losing coolant somewhere (condensation?), I only have heat when I'm running above 45-50 mph, and my engine temperature is fluctuating more than it should. My shop said something was blowing fuses, as the fuse to the blend door actuator was blown. Help?!!!

Let me add they replaced the radiator 3 weeks ago. Heater core, less than 3 years old. Thermostat, less than a year old.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the Ranger section. Connect a cooling system pressure tester onto the cooling system to locate the leak.

 

[McCormack]

You don't say which engine you have, but failed head gaskets are supposedly a semi-regular occurrence on the 3.0 engine, and the symptoms you describe could apply to a failed head gasket, so if you've got the 3.0 then that's the first place I'd look.

 

[lolapotter]

Oh, Lord! That's like a bazillion dollars, right?

 

[lolapotter]

Oh, and I have a 2.5L.

 

[McCormack]

More like a gazillion. Actually if you've got the four banger and it turns out to be a head gasket it shouldn't be all that bad. If that shop you went to is having such a hard time diagnosing a coolant loss problem, I would consider going to another shop.