a/c problems

[red83]

it is a brand new module from gm. i found one in wisconsin at a dealer. the fan was working with the old module, but it started staying on all the time and then quit working at all. so i replaced the module and still nothing.

your right on the wires. i was looking at the letter and numbers on the head unit plug(s). i checked those plugs unplugged i will check them plugged in.

this may help also...............................
i am getting approx. 5 volts to the purple jumper wire from the control module to the fan, but when i hook the purple wire to the fan it goes to zero volts.


could it be the head unit?

 

[red83]

The reason you check the purple wire from the A/C control unit to the blower motor plug/connector is to make sure it's good between those two points and not cut or an "open circuit" between them.

It was a resistance check between the two points in case the purple wire was bad that feeds the blower motor out of the control board.

Wiring colors are for an 86 year car, last available with the climate control.

In your previous test of voltages the colors appear to be the same on your module?

One is C1 (5 wires) and the other is C2 (two wires).

Do the voltage tests with both plugged in as exactly laid out above it may tell us something.

Otherwise it appears the module is bad from the data so far. :frown:

everything checks out except the purple wire. it has 0.00 to 0.01 volts.

you can unplug the ground wire that goes to the fan motor and it read almost 5 volts. but no fan movement.

thanks for your help. keep it coming please. because i am lost on this eccc.

 

[salvageV6]

The 5 volts out of the module should be over 10 volts on HI.

It appears there is no current behind it as well so when you put the fan load on the circuit by hooking up the black and purple, the module can't drive the fan and the voltage drops to 0 with no current flow.

Is the black wire on the module itself C2 pin B grounded well try a separate ground at that point to the battery or firewall ground point.

If the light green/blk stripe wire and the RED solid wire are both over 10 volts the fan should come on with over 10 volts on the purple wire.

Unless the connectors and attachment points to the board/module are bad it sounds like the "new" module is also bad. :frown:

 

[red83]

ttt... anymore opinions. tested the head unit and it checked out to be good.

 

[GNVenom]

Take another look at:

http://www.installationinstructions.com/FYI/climatecontroltech.pdf

and

http://www.installationinstructions.com/FYI/climatecontrol87.pdf

and finally

http://www.installationinstructions.com/107146.pdf

I think you have wiring issues if the control head and module all check out. The connector to the module has a common problem with corrosion and the bow connectors on the control head have connectivity problems as well.

 

[red83]

i spoke to you on the phone. you are the one that helped me establish the head unit was good. i replaced all connectors to the module and still the same.

the last two links will not open for me. never mind they are pulling up now

thanks for the help

 

[GNVenom]

Aah, now I remember...
Did you check the terminals on the brown 5 way connector? Or better yet, replace them. That's the usual source of the problem. Also, the AC clutch, has that been resolved? There is a tie-in internal to the control module.

the links are on www.installationinstructions.com - /FYI/ along with many other tech items. Look for climate control related stuff. They're all in PDF format so be sure you have a current version of Acrobat Reader installed.

 

[red83]

havent chased the compressor down yet. i did replace the teminals.

 

[GNVenom]

Another thing you'd want to check would be the diode integrated into the AC connector (spike diode). If that shorts, it'd feed back thru the module and potentially cause questionable operation of the blower circuit.

Also, if the diode is open, the spike could cause a problem. Assuming that the clutch is electrically operational.

 

[red83]

how do you check that! or would it be easier to buy a new one and replace it? i think i have bought one of these at radio shack. is there any precautions to take when sautering it (diode) on the connector? i am on my way to town now and will pick up a new diode if i can.

thanks
greg

 

[GNVenom]

Unplug the module, then at the AC connector, using an ohmmeter at the x10 scale, attach the leads to the two terminals in one direction then the other. One direction should show resistance, the other direction should show infinite (open).

 

[red83]

got some new results. i can now get the clutch to engage by adding a ground wire. initially i had to tap the clutch to get it to engage. now it will engage on its own. (with the help of the ground). i believe there was alot of build-up in between the clutch from it sitting for a long peroid of time.

is there a ground wire from the compressor that runs to the control module?
or is the ground wire on the compressor maybe grounded to the back of the head. the reason i ask this is. because i did do a motor swap. i am 98% sure i got all the ground wires on the back of the head

also, i can run a hotwire to the big purple wire on the 2-prong plug on the module and the fan will run on high.

so, i believe my new gm module may be bad?

thanks again for everyones help!

 

[GNVenom]

There are separate grounds, one on the clutch connector and one on the harness for the control module. The Caspers module runs the positive feed separately to the battery instead of through the harness/connector system, sidestepping any potential feed problems.

I suppose it's possible that the new module went bad, however, unlikely unless maybe the diode on the clutch connector is open, possibly spiking the transistor and destroying it.

You're close, real close...

 

[red83]

there is a 4 prong plug that plugs in behind the heater box. it only has three wires running to it. and the black wire is a dead-end wire(meaning that there is no wire on that terminal on the main harness). should there be one there?

is it possible this is my missing ground wire for the compressor?

 

[GNVenom]

The four cavity connector (two or three used depending on the options) runs thru the firewall with a fuse linked feed to the heater system. The blue wire is a control wire. As I recall, the AC clutch gets its ground from the electronics grounds found on the rear passenger side head, one of the 7wires there.

Feel free to ground the black wire on the AC connector to any suitable engine ground. That will eliminate at least one problem wire if that's the case.

 

[red83]

i will do that. now i just need to figure out my blower motor. damn eccc!

 

[salvageV6]

With the Electronic C68 compressor controls the ground for the compressor goes through the HIGH pressure switch on the line behind the A/C compressor and below the alternator. According to the manual:

It should have two black wires on it Pins A and B are the contact points on the connector.

Opens above 430psi. and closes below 200psi.

Measure the black wire on the compressor with an ohm meter on the X1 scale and see if it reads directly to ground Pin B on the compressor connector black wire.

The switch may be defective or the pressure not correct to allow it to pass ground to the compressor.

That would also cause you to read +12 on both wires when testing accross the clutch connector two wires. No ground present.

The open ground Pin on C497 that 4 cavity connector is where the ground would be on a Vin A motored or manual A/C Vin Y (V8) and manual A/C vin 4 (V6) car that explains the missing wire on the connector.