my a/c blower is not working, and is getting no power to the blower relay. the blower runs when hotwired. need to get the control panel out of the dash to address broken switch or loose connection.

I had the dash trim off & the control assy loose last night, but stopped before I broke something trying to get the vac lines etc off and get it out. what is the proper way to remove it for repair?

TIA~ Trace

 

Chances are, it's not the control head itself. Take it out as far as it conveniently comes, and lay it off to the side, and leave it alone.

Follow the single brown wire that leaves the "mode" switch (A/C, heat, defrost, etc.) back into the dash. About 12" of wire from the control ead, you will come upon a connector of extremely stupid design. You will find that is is burnt to ashes. Cut it off, and replace it with a set of large insulated slide terminals. Problem solved.

I've had to do this on my own car, and at least 4 other GM cars of similar age that used the same bonehead part.

 

cool, thanks. info like that is exactly why i post these kinds of questions.

still, i can't get the thing to come out more than about 1 to 2" before it feels like i'm going to break something. i was able to get the fan speed switch connector off the back, but that's it.

 

You don't have to take anything off the back, and you'll just make the job take longer and risk breakign something else by fooling with it. It's rather fragile. The thing that's holding it from coming out is the heater temp control cable, which isn't worth the trouble of taking off. Just leave the control head and all its connectors and parts alone. If you need some room to reach in there, take the radio out, which will give you some room to reach in under the control head.

 

thanks for all the help!

OK, where exactly is this plug? i pulled the radio and traced the wires from the mode switch, and they just join the wires from the fan speed selector and then head under the carpet about 6" from the panel. do i have to get at it from underneath the dash, or pull off more trim?

also, there are 4 wires coming from the selector switch (2 green and 2 brown, 1 large and 1 small guage of each color). i suspect these are the compressor clutch & fan controls. anyone know which is which, and how much voltage i should be seeing on them when they're making contact?

 

Don't worry about those. The ones that go under the carpet are headed out under the hood to the blower resistors and the compressor. Find the one brown wire all by itself that goes from the "mode" switch to join the rest of the car harness. That wire is the incoming power supply to the control head. All the compressor clutch current, and all the blower motor current in all speeds except high, has to flow through that wire. It burns the connector up.

When the car is built, each of the various sections of the wiring are separate, and are associated with their respective options. The car's main harness has a pigtail that is supposed to supply power to the HVAC system; whatever HVAC system that is installed, simply plugs into that pigtail to get its power. Power from that connection comes into the control head, and then is distributed to the compressor, each of the blower resistors, etc. each in their turn according to where the switches are set. Nothing will work if the incoming power is interrupted by a connector that's burnt to a crisp.

When you get the connector that's burned up fixed, you'll see 12V on each of those wires as their function is activated. As it is now, you'll see nothing.

 

bummer. my compressor clutch signal works, but the blower does not. found that crappy connector / brown wire, and it has power on both sides at ignition-on. it's looking to me like the problem is in the mode switch. how difficult would it be to hotwire a separate on/off switch to the fan speed selector? which wire(s) need power? the brown wire going from the mode selector into the speed selector? thanks again.

 

Bummer indeed.

Check the wire going from the "mode" switch to the fan speed switch, make sure it has power; if not, get another "mode" switch at the boneyard. If it does, check to make sure that the blue, orange, & yellow wires get their power as you select the various fan speeds; if not, get a fan switch at the boneyard.

If everything there checks out, put the dash back together, then go out to the resistors which are mounted on top of the air box, right above the blower motor; make sure there's 12V on each of those wires as the various speeds are selected; if it's there, then the problem is probably the relay.

In the 3 lower fan speeds, the 12V comes through the mode sw, through the speed sel sw, and through the resistors, then goes to the relay, which is a little box right next to the resistors. When the speed is anything but high speed, the relay is not energized, and the 12V that's been through the resistors passes through the relay and on to the blower motor via the purple wire. In high speed, the relay is energized; it then connects battery straight from the big red wire coming into the relay, to the purple wire, thus applying max battery voltage to the motor and bypassing all the other swiches & wires in the process. So, you should always have 12V on that big red wire, and whenver the fan is on but one of the lower speeds, some lesser voltage at the purple wire, and when it's in high speed, you should have 12V on the purple wire too.

As simple as the circuit is, and as easy as it is to find and replace any bad parts, I would not suggest "alternative engineering" on the system. Just track it through, you'll find the bad part, and fix it.

 

thanks. it's the mode switch.

so how do i get that mess out to replace it? do all the vacuum lines attach via connectors, so i don't have to draw / take pics of it before disconnecting? how do you unhook the temp cable?

 

You don't have to disturb the vacuum thing at all. The electric and vacuum parts are totally separate. IIRC it's 2 ¼"-head screws holding the switch on.

You might be able to get one at the parts store, I have no clue (and don't know whether you can get one either), I've never tried.

 

well, i went ahead and spliced the brown wires together (hot to the whole control assy, and hot to the fan speed selector), which got me thru a few cold mornings when i needed defrost, but obviously makes the blower run all the time when the key's on.

so i finally found a complete control assy cheap at a yard, so i'm going to clean up & lube the salvage one & replace the whole thing. so, back to the original question... how do i remove the control assy? recommended order of ops? how do you remove the temp selector cable? are the vac lines on "plugs" so i don't have to label/draw/take pics? any other advice?

also it looks like it would help greatly to remove more of the console than just the bezel around the stereo & controls... but how is that done? the only fasteners i see are under the bezel & armrest?

thanks again! :hail:
Trace

 

The vacuum thing is one big "plug", that has 2 little push-on metal retainers. There are some differences from one year to another, so you may need to take the one off your existing control head and put it on the one you get. 2 (I think) ¼" screws.

The heater control cable has a plastic tab with a (I think) ¼" screw holding the housing on; the cable inner just kind of wraps around a tab on the thing the **** is attached to.

It's really simple, everything is easy to see, no mysteries to any of it.

It's alot easier if you take the console top off. Take out the radio bezel and the radio, remove the parking brake handle & shifter ****, the shifter bezel, some Torx screws around the shifter, 2 10mm head screws under the front edge of the lid, 2 more of those same screws under the 2 back corners of the "carpet" in the glove box, lift out. Then you can take out the metal plate that the radio and the control head screws to, and everything is wide open.