[Wheels427]

I'm just finishing up my S10 350/350TH conversion, carbed motor.
I have eliminated the computer controls and now need to wire up the heater blower. I know the blower is supposed to run anytime the key is in the on position but I've never messed around with the controls that regulate blower speeds.

Can anyone shed a little light on wiring needed to get the blower running with all the various speeds? Schematics? Even random thoughts?

As it stands now I have power to the switch on the dash but don't know where to take it from there, I think it originally went to the computer. The truck is a 95 and yes, I need the AC to work also.

Thanks for any help anyone can provide

Its not the heat, its the stupidity

Wheels

 

[TooMany2count]

what i would do is go to the boneyard & get just the AC/Heater wiring harness from a 90 or older cause it doesnt go through the computor (are you sure yours did??). that way you make sure you get all those "little" pieces you may not know you need & that way its all pre-made...........joe

 

[Wheels427]

Thanks Joe, that may be the way to go. I thought I might be able to run a few new wires from the switch and one from the ignition switch If I could gain a better understanding of how to wire the resistor for the blower speeds.

Whatever way I resolve this issue, I'll post in this thread but for now I need to get packed and head to Detroit for the NAIAS to see all the new junk that I can't afford to buy and couldn't work on anyway.


I do appreciate your taking the time to share your ideas, this site has been a great source of info. Best site on the web , IMHO.

Wheels

 

[lanierledford]

can't get heat

99 s-10 blazer, Problem, it won't switch from air to heat. I got to the switch on top of the heat-air box under the dash, took the glove box door off, and can just barely see it. How do I get to it without removing the dash. Can I remove the air bag on the passenger side and reach it. I got a printout from GM and it shows its held in with 1 screw. Any help, even where to get a how to manual would help.

p.s. I've jumped out the switch on the dash and it doesn't help, I'd check for voltage there, but I haven't yet and don't know what I should get? Any help welcomed.
Marcel

 

[docvette]

Bcm

I'm just finishing up my S10 350/350TH conversion, carbed motor.
I have eliminated the computer controls and now need to wire up the heater blower. I know the blower is supposed to run anytime the key is in the on position but I've never messed around with the controls that regulate blower speeds.

Can anyone shed a little light on wiring needed to get the blower running with all the various speeds? Schematics? Even random thoughts?

As it stands now I have power to the switch on the dash but don't know where to take it from there, I think it originally went to the computer. The truck is a 95 and yes, I need the AC to work also.

Thanks for any help anyone can provide

Its not the heat, its the stupidity

Wheels

Doc here, imp:

It appears That your truck has a BCM (body control module) that controls the Heater / AC functions...

After looking through no less than 21 schematics for your truck, I can find NO reference to that module and it's terminations....It's like it was a state secret or something...But, this is where you need to isolate all the wires.From what I can determine the system works this way...:

Signal and power------->Switch------->BCM|--------->Heater Controls
|---------------------------------------------------->A/C Controls

You need to isolate the wires in/out of the BCM (when you locate it) and determine if they require low voltage Signal...Or power to bypass them.

If you STILL are using the BCM, Use Care, General Misery Warns about using ESD equipment (Electronic Spark Discharge) Tools around These circuits & Switches..as they can render permanent Damage to the system..

I assume because (the big state secret box) BCM has MOS or CMOS chips inside of it, where a static discharge from hands, clothes tools, can blow a micro hole through the chip substrate..

I can tell you that the Heater / AC motor has the resistor mounted on the outside (Firewall side) of the plastic shroud, plugs in like a fuse , and is held in place by one screw at or near the motor plug....(if that helps at all..)

Best bet is locate that BCM and backtrack the wires...

If you removed the computer PTM (powertrain module) The BCM MAY still be in operation..as all the wires I could locate were inputs to the module, not power or grounds...but low signals...And if I determined correctly , lots of other stuff would be inop if it were not at least partially working, like lighting, warning lamps and buzzers, wiper speed controls, Air Bags ...and the like...So If I had to -->*Guesstimate*<-- That module SHOULD at least be partially operational..

If you wanted to you COULD abandon the Harness for the system for heating and air and wire it straight for Non computerized (as mentioned before) But the task would be massive as you would have to analog wire things like vent doors, zone temp sensors, Compressor Clutch relay (s) ,Panel switching, and limits, and speed sensors..

I would research the library reference desk or try a haynes or chilton for a diagram that INCLUDES the BCM schematic and attempt repair in that direction..before going the other way..

Sorry I couldn't be more help..

Doc imp: