Electronic touch climate control


Sep 2, 2001
anyone familiar with the electronic touch climate control unit? No matter what mode I'm in (econ, auto, etc) the fan is on hi speed thru the vents. I pulled the board out in the engine compartment where I hoped to find the resistors for the different blower fan speeds but found a pc board full of components instead. After doing some troubleshooting of this board, it seems ok. So I yanked the control unit from in the dash. Without a schematic, one would guess "HI" would be a full 12 volts, "LO" would be 4-6 volts, and "AUTO" would be any voltage between the others depending on the temp chosen. Well, "HI" and "AUTO" seem normal. On "LO", the voltage jumps all over the scale. OK,OK, too much info! Anyone have a schematic or another unit I could swap test with? Then again a big Frankenstein movie high voltage knife switch on the dash may be in order.


85 T
I had a simular problem but was stuck on low. So I wired a relay to switch it from low to high. I will assume the that part is bad? My friend that do auto a/c said that part allways goes bad.
If you wanted to try to switch out with mines, i'm off on mondays, if you can swing by my house.
G-man, check your mail! i think i filled your mailbox! clear it out so i can send you the rest!

G-man could you give me the part number again cause I accidently deleted all my messages in my inbox, and also you e-mails I sent you keeps on getting returned?
Its my fault!

Jackson, I stuffed g-mans mailbox with the scans of the service manual thats why your mail is being bounced back. -Rob
Electronic headache control

Jackson, can I get your cell number again? I dumped my e-mail without saving it. The part number is #25500218. Appreciate all your help. Rob, thanks for all the diagrams. I still am going to attempt to fix this @#$%& thing, after I buy a new one. Normally, different resistors are used for the blower fan speed. This @#$%& thing either uses 12v for hi speed, or get this, it pulses the 12v on the lo speed setting. No resistors for dropping the voltage to the blower fan for lo speed. They change the duty cycle on the fan. The pulses turn on and off a transistor that passes the 12v to the fan. The pulses can probably be seen with an oscilloscope. A voltmeter will just show a jumpy voltage, making one (me anyway) think something is wrong. As if anyone cares............ What really is amazing, though, is this type of technology is cutting edge, especially a car made in 1985!!!!!! Normally, this technology was starting to show up in the 1990's and later. Just more stuff to let us know these TR's are REALLY special!!!!

:D :D :D
Old cell is 754-7342(still works)
New cell is 864-4467

I price is $116.65 and retails for $155.65. Another thing you could do is get a manual high/low fan switch at a local parts store and wire it in to the fan?
resistor block and manual switch

thats not a bad idea, except the board also provides the compressor cluth signal. -Rob
Electronic headache control

Jackson, yes, I want the part. And Rob's correct. The damn board also controls the compressor clutch. So I'll just fork over the dollars and end this fiasco. Will call you if you don't call me first. Big Mahalo!!! Now on the other side of the coin, a manual switch ain't a bad idea, leave the compressor clutch on ALL the time, create an arctic zone interior, hmmmm................

:D :D :D

OK, received more info from a private e-mail. Was able to draw a schematic out which helped big time. Replaced 2 of the 3 transistors. The 3rd transistor is rated at 50 amps max collector current. Honolulu Electronic stocks it, but it's on back order right now. Maybe 2 weeks. I tried a cheap 99 cent 15 amp job from Radio Shack and it worked. Well, for a minute on HI till it cooked itself. When this is all said and done, I'm gonna be the friggen expert on this damn controller board.

:confused: :confused: :confused: :confused:
Climate control touch

I say your post about the Electronic touch climate control. If you have the service manual on that part, can you e-mail it to me ??
I found p/n number 25500218 at www.gmpartsdirect.com for $ 82.05 plus shipping. e-mail address: dadmomcat@juno.com

Did replaceing that controller help you. I have NO fan at all. Fan motor is good.

It's been soooooooo long since I worked on that module, it's all a big gray area in my mind. After drawing the schematic out, the problem kinda showed itself. There's a PNP power transistor that usually goes. It sinks a lot of current. The replacement is an NTE30 which you should be able to find at your local electronic parts supply store (except Radio Shack). This transistor is rated at 50 amps max current handling. That's why the board shares the fan housing with the blower fan: to help keep it cool. I think the part was about $15. A little soldering time and you will be up and running. You can e-mail me privately if you need more info. Just need to sort thru the cobwebs.............I should have posted my results but Chris (Turtle TR) and Rob (HI85WH1) wanted to go eat lunch so I followed and forgot what I was doing ! :D :D :D

Would it be easier to swap out the electronic climate controls to a non-electronic. Replace the switch pannel on the dash and the fan switch relay/module?
I have not looked at the non-electronic climate controls nor schematics so I wouldn't know for sure. I do know the module also contains the A/C clutch control signal so my guess would be NO, not easier to swap out. I am an electronic technician so for me it was easier to repair the module (having the needed tools, etc). If any of you guys need repair on it, I'll gladly do it for you (Hawaii gang). I spent enough time trying to figure out that blasted #@%$& module it burned an imprint on the inside of my eyelids. Hope this answers your question.