Heater Problems Got any Ideas???

[99MBSport]

My heater on my 97 Ranger 4X2 seems to be on the fritz. When I turn the heat control knob it makes NO difference. The heater blows HOT all the time. The center knob that controls the temp is a wired knob not a hose type. There must be a relay or a control somewhere that regulates the heat. Has anyone had this problem? If so please let me know it's driving me batty trying to figure this one out.

[rhandwor]

Check the vacuum line coming from the engine it opens a blend door on the heater box.

[Selectron]

I'm not familiar with your vehicle but I had a look at the wiring diagram for it and it seems likely to be a problem with the Blend Door Actuator circuit. First check would be fuse 10 (7.5A, located in the interior fuse panel). If that's ok then you'll need to start checking the circuit - the procedure is explained in detail on this page.

I believe this is the wiring diagram for your vehicle - the wires leading from the temperature control knob to the actuator should be grey/red, dark green/orange, and yellow/light green. The testing procedure is very well-explained so I can't add anything to it, but if you need any help on the electrical fault-finding side of things, interpreting voltage readings etc, then let me know.

[Selectron]

Oh, I was typing while you were posting, Rhandwor. I came to the conclusion it was operated by an electrical actuator but so long as one of us is pointing in the right direction, it should enable 99MBSport to make a start on fixing it.

[99MBSport]

Had some time and researched the problem and found that the Blend Door is a common problem with Ranger/Explorer. I see where the actuator has a 90 degree swing to open the door inside the heater box BUT the area is more like 65 degrees. So the door is under constant pressure when fully closed causing the shaft to break at the top. There are numerous places that can be searched on this subject. I took a dremmel and opened up the heater box from the bottom and removed the door and put it back together with pins and some epoxy. Works great now and saved myself over $1000. The stealer wanted to take the complete dash out and remove the entire heater/AC unit to do a replacement of the heater box door. By doing a hole in the bottom there is no need to tear the dash apart. You can epoxy the heater box back together and being on the bottom, you can't notice it unless your on the floor looking up. NAPA also sells new heater box doors for $10.99 plus shipping. Very simple fix and saved a crap load of money. Do some research on Google for Ford Ranger Blend Door repairs and you'll be astounded as to what you can do. Hey the $$ is better in my pocket than the stealership.

[99MBSport]

http://www.explorerforum.com/forums/...d.php?t=214332

Here's the link for the repair to the Blend door.

[backerm1]

$1000 just for the heater repair?!! now there's some intelligent engineering.