OK fellas long post but bare with me. I have a 94 Explorer 2 wheel drive with 175,000 miles. recently it started not blowing hot air (heater). this is what I have done so far. New water pump,new thermostat and radiator cap, new heater control valve, radiator rodded out (guy said it was very clean inside already but side tanks had small leaks), heater core about 2 years ago and flushed and backflushed within the last 2 weeks, 1 1/2 gallons of new antifreeze. now it still wont blow hot air. Water temp gauge dances between just below the N to just between the R and M in normal. As soon as it gets to the M it drops back to below N and then immediatly starts climbing back to the M. I am curious do I have the 2 heater hoses going to the control valve switched? would that make a difference? PLEASE HELP!

 

Go to the Recall/TSB portion of the FTE site and look up your truck. I have a 92 that suffers the same problems. There are 2 TSB's that deal with our problem, but they don't offer a solution. I plan to get in touch with my local dealer and see if he will divulge the contents of the TSB's. If I figure it out, I'll let you know.

--John

 

Thanks for the info...I think I will contact my local dealer as well..but with almost 170,000 I dont think they will be much help.Also these things didnt start until just recently. Before that the heater would run you out of the truck, now it hardly blows warm much less hot.

 

Check the heater hose after the truck has run a while. If both hoses hare hot you are getting hat water to the heater core. If only one side is hot it is still plugged. The back flush should have fixed that. The next thing is the plenium chamber. This is where the amount of air going thru the heater is controlled by a air blend door. Try to figure out if that door is opening and closing sufficently.

 

Avanti is on to it. Check those hoses in and out of the heater core. The core shouldn't be plugged but your heater control valve could be your problem. You may have piped this up wrong during your repair. I have a 95 which was the model change. It has 4 hoses hooked to it which can be easily turned around. The actuator motor (vacuum) could be malfunctioning also, something else to watch. Maybe someone with a 94 Exp can describe the way their heater control valve is plumbed. Good luck.

 

OK fellas...I checked it out again and DID find that the heater hoses were in fact crossed. So I now have hot air coming from the vents. BUT I do also still have the crazy acting temperature gauge. it goes up and it goes down, like a crazy roller coaster.I guess I can live with the gauge acting like that as long as I have heat. Im curious though, I wonder if installing a real temp gauge would show the same irratic behavior?

 

Well at least you got your heat back. Not sure where you live but here in Iowa we can't go long without any this time of year. Get yourself one of those automotive multimeters. They have dwell, volts, ohms and some also have a type K thermocouple. This thin lead can be used to measure temperature quite accurately. Attach it to your radiator hose and see if the meter does the roller coaster routine. If not, replace your $15 temperature sender and your good as new.