HI guys. I have a 95 f250 7.3 and in the five months I've owned it, it has never gotten up to normal running temperature. I live where it get's pretty hot and the temp gauge never gets past the N in normal and now I just tried to use the heater and it's not blowing hot. Blower works because the a/c blows cold and I found the hot cold switch works trying to get to the heater core. Side note- it runs on veggie oil or diesel and the heater tubes also heat the veggie oil. Not sure if that has anything to do with it.

 

What thermostat do you have?
Have you tried testing it?
You might need the higher temp one.

How is the veggie line tied into it? Have a diagram?

 

I haven't tried testing it. I'm sure I can reference YouTube to figure out how to test it. As for the diagram, it just looks like there is a few T splitters on the intake and return heater tubes that lead into the fire wall to the heater core.

 

Is the blend door in the heater box working correctly? Junk can fall down the defroster vents and block the door from working correctly. Removing the panel located on the front of the heater box directly behind the glove box will allow you to check out the blend door.

 

do you have a restrictor at all? I have seen some people tee off and with out a restrictor you can have odd results. Also a tee can create a venturi and work opposite of intended use if you don't plumb flow going into the middle of the tee


These diesels run cool, don't take much to take the heat away


test t stat with pot of water and a temp probe on the stove


some like the higher 200 f t stat for heat