Shdwjim

I backprobed C3 dark green and orange and it's still showing about 9volts. I checked it again at the blower resistor module terminal C dark green and yellow and it's showing the same voltage. I supplied 12 volts to the terminal C dark green and yellow but it didn't make a difference. I verified 12 volts at the red terminal B and the ground at terminal D. I also checked for any spread terminals and they look good.

PatternDayTrader

Well I certainly see why you already replaced the blower module. I would be expecting it to work. The 9 volts seems suspicious, but if nothing happened when you applied 12 volts then maybe not. I'm sure you cant substitute it with a known good part.

Shdwjim

I was hoping that by installing the NOS part that I was eliminating the chance of it being bad. I did notice that the 9 volt voltage appears to be slightly different depending on temperature. When I checked it again the next day when it was hot out again. The voltage was back up over 9 volts and when I cooled off in the evening it dropped back down slightly under 9 volts. I'm not sure if it's just coincidental. Do these cars have it set up for the blower to not blow easy until they warm up or cool off? This car is blowing hard on auto as soon as I start it. I'm kinda grabbing at straws at this point.

Shdwjim

Something else that may be of interest. Where is the compressor diode located. I was guessing that it was built into the compressor clutch because I don't see any place for it. The original connector was cut off the compressor and the harness so I had to install a new set of connectors.

PatternDayTrader

The temp thing doesn't concern me. I'm sure you are right thinking its coincidental. As long as the voltage at the back of the control head is the same out at the connector. The blower blows like crazy on startup (auto setting) because its attempting to achieve whatever temp the control head is set on. For purposes of solving this issue, I would say don't do any testing on auto. The compressor may or may not be requested on auto depending on the temp sensors. So for testing, use the coldest temp setting and manual blower.

PatternDayTrader

The diode is located literally at the clutch connector. The ends of the diode at literally crimped into each terminal of the connector along with the wire. The diode parallels the clutch coil. If its installed backwards, I would think the clutch wouldn't engage but it should also blow the circuit fuse. Maybe take a look at that again to be certain.

Shdwjim

The diode issue is throwing up a red flag. I'm pretty sure that there's no diode in this system right now unless it's built into the compressor clutch itself. The guy who installed the power switch cut the connector off the compressor and off the harness. I don't see any indication of a diode.

PatternDayTrader

In my mind, I'm not getting why there's just 9 volts for the compressor on input at the blower module (terminal C drk grn and yellow). It seems like there should be 12. Does that circuit voltage go to zero when you turn off the ac ? Seems to me, that terminal is just the base of a transistor with terminal A of the two wire connector as the collector and terminal D of the four wire as the emitter. I guess I would want to verify dr grn and yellow (terminal c at the module) from the control head is actually turning power on and off to the blower module, with the ac request. I'm reasonably sure that how this circuit works based on the schematic, but maybe not. The next thing I would verify is that the ground at terminal D of the four wire connector can actually carry some amperage. Its entirely possible that a test light, could light, using that as ground but something with a few amps like a compressor clutch may not. In the field, a tech would scab up an actual headlight as a test light to allow a meaningful amount of amperage to pass through that circuit. You might be able to do something similar. In any case, if that ground cannot carry some amperage then the circuit wont work. One things for sure, you definitely have an interesting problem with this one.

PatternDayTrader

This is typical.

PatternDayTrader

The purpose of the diode is to prevent voltage from spiking the system when the compressor is turned off and the em field collapses back through the clutch coils. I would expect it to work without it, but cause problems with the other electronics. In the event there is a diode somewhere, and its installed backwards, this could wreck al kinds of havoc.