89 Roadster, Electronic AC controller module, Inside LH center firewall.

Before I lost all function the Fan only had one speed. full, and then wouldn't shut off with the ignition off, so I unplugged it, then it completely stopped, so I bought a blower relay only to find it doesn't have one, Previous to that no heat control, Only hot.

All lead to this being the likely problem component, having replaced the Dash Control unit and it not clearing up the first problem, and now developing into no AC functions at all and am getting tired of no heat or defrost. (except when moving at speed and warmed up, And that only because I manually control the heat door, if going around a corner doesn't turn it off)

I have all the info on repairing it found in previous posts or will just try and find another if I can't fix at least some function.

Before I tackle it, Any tips from anyone who's removed it besides removing the seat for big guys like me to be able to at it easier?
Looks pretty tight up in there with poor visibility and it not covered in my Haynes as to procedure. It also looking like not much if anything else needs to be removed to get at it, but.....? Thanks in advance.

 

http://members.shaw.ca/dankai/AC%20Electronic.pdf

 

Thanks, I got it already as well as the rebuild instructions for the programer, But now....

At one time I thought I was able to get a code out of the controller, I can't seem to get one now and it showing no problem codes. Being a convertible doesn't have a rear defrost, but think that the mirror defrost serves the same function.

Playing with the buttons, I can only get a "00" then appearing to run up the fan speed and temperature. Neither of which work, Ignition on or running, though do get a clicking under the dash of which I think is the mirror defrost relay clicking on or off and something else when it isn't that's possibly associated with the outside temperature. That light goes out with a click among other clicks.

Unless I'm doing something totally wrong. Daylight I'll have to try some other tests, but pretty something needs to be replaced.

 

If the blower is high speed only and/or continues to run with the ignition off, the first thing to check is the 5 amp fuse that protects the circuit carrying the actual blower voltage back to the Control Panel. That circuit is spliced into the hot side of the blower (Purple) and the fuse is mounted on the Firewall to the left of the Evaporator Core. Find the Purple wire and you've located the fuse. If it's opened, replace it and see if the Blower works correctly.

If the fuse is good, Blower gets it's power from a Module mounted on the left side of the Evaporator case. There are two connectors. The important wires are Red - hot from a fusible link from the Starter Motor. Tan - a low voltage signal from the Dash Control. Purple - the output voltage to the Blower. And Black - ground which is spliced into the Blower Motor ground and terminates on the frame below the Blower Motor. Check the Red for 12 volts. Check Tan for about 2.5 volts with the Controls at "1" and 6 volts at "10". Check the Purple for 4 volts at
"1" and 12 volts at "10". Ohm out the ground from the Module to the frame. The Module is used for all GM electronic a/c's so if you need it, you can get it at any Dealer or NAPA has a stocking number.

Diagnostic Codes are of limited value on the '89, but "00" means there are none. If you had a Code "01" - open in the Temp Door Motor return voltage signal, you would suspect the Motor, it's wiring or the Programmer, but you apparently don't have any codes. If a code was set, the LED at the Outside Temp Indicator would be blinking.

Air Temperature is controlled by a door in the Evaporator Box that's moved by the aforementioned Motor. View the door by removing the Blower Module and as someone operates the controls, see if it moves between 60 and 90. If not, the linkage is connected to the motor with a plastic clip and it may have broken. Access the motor and it's linkage by removing the Passenger's side hush panel and the ECM. If you disconnect the motor's electrical harness, nothing will work again until the Control Panel relearns the position of the door and the Outside Temp Readout may display a -32. Control Panel determines door position by cycling the motor/door from fully opened to fully closed. Takes a couple of minutes. You should disconnect and reconnect the battery first.

If the door works, the heater core is probably plugged up. You can try to flush it with a garden hose or compressed air. If it is plugged, check the cooling system for galvanic corrosion and if evident, make sure it doesn't have a leaking head gasket.

 

Thanks, When I originally had a problem someone told me the door motor rarely fails and to replace the controller. Coincidentally the heater core also went, so the core has been replaced as well as the controller and most of the dash is still apart so I can still get at everything. Then someone said it was likely the module inside above the gas pedal.

I disconnected the rod from the motor so I occasionally have limited heat control.
Thanks for tip on how it works and how to test and reset it, I can't remember where it was fixed when I disconnected it.

It's been a while since and then the problem with the fan speed started after sitting a long time outside in long wet weather. then it not turning off at all and failing completely shortly later.

All fuses good, Never seen any flashing lights on the controller and switched to outside temp to see if anything happens.

For the diagnostic, I thought the numbers were preceded by a -, And do get 01 etc starting with 00, and it appearing to run up as I press the buttons. pressing the warm switches back to temperature, but according to the manual is supposed to cycle to the next function diagnostic, but seeing it appears to start at 00 isn't registering any other problems?

I'm presuming that's another module where the two plugs enter the evaporator case on top inside the engine compartment beside and above the Blower inside the evaporator case or is this module in reference to the inside on the left center firewall above the gas pedal? The wiring diagram doesn't appear to show where everything is or I'm just not reading it well enough and printer is working to take it with me when I look.

The color of the wires sounds right for the plugs inside the engine compartment on the evaporator case, but the tan looks more brown on mine, it smaller so suspect it's a low voltage wire and I'll check them next and or pull out the unit to see if it can be fixed. Easy to get at.

 

Ok the Blower Module is the one on the Evaporator Case mounted on the right side of the Firewall. The two connectors have 6 wires. Red is Power. Tan or Brown is the Blower Input from the Dash Controller. Purple is the Output. Black is Ground. Green is compressor Ground and Green/Yellow is the Compressor Signal from the Dash.

The Programmer, above the accelerator does send the electrical signals to control the Temp Door Motor. Looks like you've verified the linkage. With the dash apart, you should be able to access the motor and it's harness - I would make sure that it isn't going through a reset procedure first - so disconnect and reconnect the battery and then turn on the ignition and see if the motor cycles. Otherwise, Tan/Black and Yellow are the signal wires. In one direction, one will be hot and the other ground. Voltage is reversed for the other direction. If there's no voltage on these wires, you probably need a new Programmer - though some have resoldered/replaced board components. Not too difficult to access. Just get on your knees at the driver's side and look above and to the right of the accelerator to see it.

I too have come up with an "00" without having to page through any of the Modules and I've guessed that's because it's allready at Mode 8 or the Diagnostic Mode. See what happens after disconnecting and reconnecting the battery or you can pull the Courtesy/Clock Fuse which is Memory.

 

Thanks, Right on !, Forever indebted,

Re : Door Motor, Much easier to understand than the manual. I wish I had this info when the problem first started and saved the price of a new controller. And suspected this needed to be tested, but no one could tell me how to test it. Let alone that it needs to be reset . At least now I should be able to isolate which is the problem now.

If it's the programer, I have a good friend who likes to work on electronics, but being a big guy the programer under the dash is a little hard to get at, but doable if it needs work and I'll at least get him to look at it with the rebuild instructions before buying another.

Fortunately that side of the dash is also still apart, The top pad is still loose also, so pulling it out might put more light on it.

 

I finally got around to the easy diagnostic on the module on the evaporator case.

I'm using a digital tester that seems to occasionally register something even when not hooked up or minimal voltages. 000- 004-005v. Tested not quite like procedure in the manual, but should still get the same kind of results.

With the ignition on, Climate control set on Economy and fan speed set at 1, The tan wire registered 6.71v+-, At 10 it registered the same 6.71v testing a couple times comes up with 005-010 variances,
(And this why the fan only ran at high before failing)

12.05v voltage on the red, (but did get a couple errant no volts) this also hot with the ignition off.

The purple wire testing odd. but conclude 004v at fan set at 1 & 10 but also got no (004v) voltage on the purple wire at 1 and at 10 fluctuated minimal voltage and flashed "-" and -000v. This being the power wire to the blower and isn't getting any juice.

So it looks like this module isn't working anymore to turn the blower on (or off), (This unit also non serviceable) or the controller isn't working properly to send the appropriate low voltage, (If not too high? The manual indicating 5.5v expected at the brown wire) for the slower blower speed

Ignition off, And purple and red jumped together produces fan speed, Looking at the wiring diagram, This is normal because the red wire is hot all the time and the AC/Climate control circuitry and this module is supposed to stop the voltage when the ignition is off.
(As explained in an earlier post and the functions of all the wires seem to indicate no power or interruption comes from elsewhere)

Now it's looking like the controller head is next if the errant voltage on the brown wire isn't caused by the the module that controls the blower speed, In lieu of testing the control head yet and so far looks like it's not connected to the inner module that might be connected the door motor next on the agenda....

 

2.5 volts should be the input to the Module at "1". However, the Dash defaults to a high blower if the return voltage is open. That's the 5 amp fuse on the firewall and with nothing getting to the Blower, nothing is getting back to the Dash. If the fuse is good, still sounds like you need a new Module.