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Either EXTREME cold or EXTREME heat...

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City, State
Lewisville, TX
Year, Model & Trim Level
1997 Explorer Sport
Hey everyone, Happy Thanksgiving! I've been using this site since 2009, luckily my 97 Sport hasn't been problematic. This is an A/C issue...the cold-hot knob does nothing on my Explorer. If you move it to full heat and put the selector knob on Max AC it comes out the vents ice cold... however move the selector knob up one notch to AC and it will burn your facial hair off and that's even after putting the cold-hot knob to cold. There isn't anything wrong with my blend door though...defrost comes out the top of the dash, heat or cold comes out the floor, dash and floor, etc. For the life of me I can't figure out why it blows extreme heat on the normal AC position and the compressor is running but one twist to MAX AC and it comes out ice cold and the cold-hot knob is all the way over in the RED lol. Before anyone goes there... yes, I DID replace the A/C control unit as a whole with a used one from eBay...same exact thing. The heat is so hot I can only run it for a minute or two then my wife complains so I turn it off, then she gets cold and complains so I turn it back on... imagine that on a 4 hour trip from Dallas to Houston!! Someone please help LOL. Happy Thanksgiving to you all by the way.

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koda2000

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You heater/AC plenum box has multiple doors and multiple actuators. This is what controls the air flow and temp. On Max A/C the area of the plenum which houses the heater core is bypassed to insure maximum cold air, which is also recirculated inside the cabin, so the path to "fresh air" is also closed. Some of the door actuators are electrically controlled (like the heater blend door) but most are vacuum controlled. As you don't seem to have a vacuum leak you may have a bad vacuum actuator motor somewhere. You year also has has a heater control valve, which opens of closes the hot water to the heater core. Make sure this valve is working.
 




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1997 Explorer Sport
Even though I've owned this thing since 2008 I have no idea where to start looking for vacuum actuators and motors...can you give me a starting point reference?
 




koda2000

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Even though I've owned this thing since 2008 I have no idea where to start looking for vacuum actuators and motors...can you give me a starting point reference?

They're under the dash. I know there's one on the right side of the plenum box and one on the left. Someone (Turdle?) has posted a diagram of the plenum with the motors and doors and vacuum lines. I may have it, I'll look. As far as the heater control valve, it's under the hood, passenger side, near the firewall. The heater hoses go to/through it and it has a vacuum line to open/close the valve.
 




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Lewisville, TX
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1997 Explorer Sport
I'm familiar with the heater control valve under the hood. I had a melted line from the canister near the front to it a few years ago. Replaced the line and got it to function again. The middle knob with the temp selector...that one should be electrically controlled am I right? I do remember when I first bought this Sport I couldn't get heat...so I twisted the temp knob back and forth a few times and then the heat came out but I could never get it to go back. It's been stuck on heat for 8 years.
 




koda2000

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Joined
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City, State
Lewisville, TX
Year, Model & Trim Level
1997 Explorer Sport
Koda I went outside and dumped the contents of my glovebox and saw this unit with a wire harness. So I turn the key forward and the AC on and started twisting the cold-hot knob and I hear a faint motor noise...the more I turn either way the longer the duration of the motor sound, the less I turn it the quicker the motor sound starts and stops. I can't understand what is wrong, possibly a linkage broke on the blend door or something?? I know one thing...if it requires removal of the dashboard my old lady is just going to have to get some blankets this winter lol.

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koda2000

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Yes that's the blend door actuator. It controls the amount of hot air that is introduced into the system by opening or closing the blend door, so if you have the A/C on and it's too cold in the cabin you can add some heat to the air flow to warm up the cold air a bit (blend hot and cold air). I don't know that the blend door has anything to do with your problem, but it's not uncommon for the blend door to break on these vehicles. If it does break you will not be able to regulate the amount of heat you get.

If your blend door is broken there are two ways to replace it. One is to remove the entire dash and heater plenum. The other is to cut a hole in the plenum. There's a STICKY on doing the cut a hole method repair.

The blend door actuator on my daughter's 2000 Mountaineer stopped working 2 years ago. I hooked up a piece of bailing wire to the actuators crescent gear and I open the door in the winter and close it in the summer. She doesn't want to spent the $60 or so to replace the actuator, so good enough. Her truck has the EATC HVAC controls, but both the automatic and manual HVAC controls work the same way, although the blend door actuators are different.
 




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Found the culprit...broken collar on the upper keyed hinge where the actuator goes into. I'm not taking my dash apart to change that out, super glue or two part epoxy here I come!
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koda2000

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Yep. That would be a broken blend door. I don't know that you can glue/epoxy it back together, but good luck.
 




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If push comes to shove I'll just manually move it by hand...I cut a trap door out down by the fan and heater core box LOL! It's Texas, we don't get that cold often so it won't be a pain to switch it by hand every now and then. Thanks for your insight and photo links!
 




koda2000

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lobo411

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Yep, what Koda said. Just fix it using the simple procedure outlined in the sticky. Takes about 15 mins of actual work once you've figured out exactly what you need to do (ie translating instructions to action).

If you've gotten the actuator screws out, then you've done the part that most people find most difficult.
 




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I had already cut out the hole so I could reach in and move the blend door by hand. So I just basically put a little resistance on the blend door to see if it would actually flow with the actuator transitioning from hot to cold and it did! Took a file and roughed the arm coming from the bottom of the actuator and mixed up some two part epoxy and smeared it on there evenly and stuck the actuator back in place. I will be getting back with you guys in a few hours for an update on results...it's time to watch some football lol!
 




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Ok fellas, I came out to check it... IT'S ALIVE!!!! (Dr.Frankenstein)

Man I'm so happy...the key to making this hack work is to drill a hole in the actuator arm before you put the epoxy on it, smear some in the hole and then around the actuator arm to make sure it gets a firm grip on the blend door piece that is broken. Patience is a virtue for real!
 




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Three weeks later...still working. Will update again after a few months.
 




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