'97 with little no heat

[jbd172002]

I just bought a great '97 XLT to add to my ever growing collection of Explorer/Rangers. It has a few issues I need to address.
Currently it puts out moderate heat, at first I thought it was a thermostat because the temp was staying cool on the gauge. More like not rising at all.
I've come to decide it's a separate issue. It doesn't seem to make any difference where I position the temp knob, it puts out moderate heat, it never gets cold and it never gets "hot". The fan works just fine in all speeds, the air flow works fine, always going to whatever vent I've selected. So after scoping out the car fairly well, and combing through my '96 shop manual I've decided that it must be either the temp control door, or the control of said door.
Does anyone have a similar problem, or one that they've fixed?
Also the bypass valve seems to be leaking a small amount of coolant, but again I think thats a separate issue also.
The temp gauge is baffling me though because I replaced the sender unit and it didn't solve the problem so I'm not sure why thats not working. So any thoughts on that would be good too.
Thanks for your help in advance.

 

[my98nnj]

The heat issue is most likely the blend door, a very common failure item on these trucks. Test the actuator first by taking it off and watching it move as you turn the knob. If that works, you can follow the instructions up in the stickies on how to verify the bad door and replace it.

As far as the temp gauge, did you replace the correct sensor? There are two of them, one is for the ECU and the other is for the gauge. Check the wiring before you replace the sensor as corrosion may be a factor too.

 

[jbd172002]

temp gauge

Yeah I'm pretty sure I got the right sender unit. As I understand it, there are two, one is a sensor unit, one wire, just left of the water neck. Thats the one that supplies the dash gauge. Thats also the one I replaced.
I see another to the right of the water neck, which appears to be a two wire, as I understand that it's just a switch sender that supplies the ECU. That I have not replaced.
Am I on the right track?
I will check the one connector for corrosion, as soon as my girlfriend gets home.
I'm gonna play with the blend door thing when she gets home too.
Thanks for the info.

 

[rollinstone]

Check the "Blend Door Fix" sticky here.

 

[Turdle]

Low coolant will cause both symptoms. Also, since the bypass valve is leaking it may not be working.

 

[jbd172002]

I replaced the bypass valve and checked/topped off the coolant. No leaking now, but heat still the same. I think it's the blend door, I'm not looking forward to that, but it must be done. Right now I don't have enough heat, but I know soon I'll have too much so a proper fix needs to be done...Meh.

 

[jbd172002]

Update: Now have heat, works great.
I got the doorman blend door repair kit, cheap only $12, it comes with everything to do it properly assuming you pull the airbox out of the dash. Given the current weather and my apartment living situation, removing entire dash was not really a practical option. So upon searching and reading all of the blend door fix threads and websites I could find. I took my harbor freight rechargeable "dremel" tool and cut a large section of the front of the airbox out, directly behind the glovebox, that piece came out very easily (and consequently went back in very easy.
then I cut a fairly large section out on the bottom directly where the door swings and was able to remove the broken door out the front, sticking my hands in both the bottom and the front.
The old door was as I assumed broken in the normal spot where it connects to the actuator.
To this point probably took maybe 30 min to do.
I worked quite awhile longer and had to shave more plastic off the bottom of the box to get the new door in.
After some aggravating moments and cutting more plastic than I originally intended to, I got the new door in.
I reinstalled the actuator and turned the car on and checked to make sure the new door swung and operated as it was supposed to.
Everything was perfect.
So to speak.
I got my permatex 2 part epoxy and was able to fairly easily "glue" the front section back to the airbox, I used some strips of duct tape to hold the seams together while it dried.
The bottom of the airbox was another story because that didn't come out in one neat piece as the front had. So for now I used a fair amount of black duct tape and carefully taped the bottom up so that it's usable.
My next step is to get a new piece of black plastic, cut it slightly larger than the sum total of the bottom cutout and epoxy it in place.
Overall I'm very pleased with the outcome.
It works as it's supposed to, the actual outlay of money was about $15 including epoxy.
I already had the dremel tool.
the total job probably took less than 3 hours start to finish.
It also very much pleases the GF, as this X is now her daily driver.
Thanks all for help and advice.
I'll try to post a few pics when I get a chance