No A/C Blower - 1995 W124 E300 Diesel

[austxjr]

My fairly new 1 owner (before me) 1995 E300 Diesel does not have any blower for the climate control anymore. Here are the symptoms and what I've done so far to diagnose/isolate the problem:

• 1995 W124 with OM606.910 diesel engine - 132,000 1 owner miles
• Car still starts, idles and runs fine - A/C/Heater blower and recirc blower don't blow.
• It did this a few times and then worked again, but has finally stopped working. Nothing happens when either of the fan switches are pushed nor when temp dial is changed... cold, hot, etc.. nothing.
• SRS Light comes on shortly after starting engine and driving with A/C Climate control on - I noticed this the first couple of times the blower stopped working. Next time car started the blower worked until recently.
• ABS light also sometimes comes on after a few minutes if Climate controls are turned on (blower switch - auto and both A/C and temp must be in position and compressor going).
• Checked ignition switch and steering wheel airbag to see if they had any effect on SRS light - none.
• Compressor comes on and A/C lines get cold fast - when switched to external air and driving on hwy, cold air comes in for a while.
• I can hear the flaps opening and closing when switching between A/C modes. Fresh air does come in when proper switch is pushed.
• I'm assuming blower is still good because each time it resumed working it ran just fine and the 30 A fusible link (or is it 15A?) to the blower is still OK.
• Hissing comes out of A/C vents when A/C is on for a couple of minutes after start (I turn it off quickly so as not to damage climate control)
• Auxilliary fans in front of radiator do not come on at all
• I have removed and tested the OVP relay - it shows 0.51v when tested in diode mode - no rattles. I'm assuming it is good, though I may replace it as a precaution. I have not opened it up and checked solders yet.
• Red light on recirculation fan switch comes on but recirculation fan does not blow either. I'm guessing that a whole circuit with both fans is turned off because of a over or under-voltage or current condition but if it isn't OVP then what is it?
• When I drive on the Highway without the climate control engaged the SRS and ABS lights do not come on at all and when tested in a parking lot the ABS works quite well (no, I haven't tested the airbags for SRS and don't intend to do so).
• I have acquired the workshop manual and schematics and am beginning to trace the issue down, but that is a big task.
• Next Step: I'm going to have the alternator, battery and the voltage regulator tested and inspected to make sure that voltage isn't down below 13v. After that I will likely open up the fan housing and test the fan independently (and replace the motor if need be - replacement fan is about $90) to eliminate that possibility.
• Thought 1: it could be one of the temp sensors going out, but there seem to be about six temp sensors and I'm not sure where to start or how to test them properly.
• Thought 2: I hope it isn't the control unit for the blower because of price, but it certainly is possible, however, I'd like to eliminate all the other more common and less expensive options so any feedback is welcome.
• I'll probably test some variations of having the Climate control on - does SRS and ABS only come on when cold/compressor are engaged or does it happen with heat and blower turned on?

I hope this is enough good info for those of you inclined or experienced enough to help with the diagnosis. If there is something else you want to ask, just let me know.

It sure seems like a voltage condition because of the intermittent nature at first and also the fact that SRS and ABS lights only come on when the climate control is turned on. Any hints, ideals or experiences that might bear on this would be greatly appreciated. I've already taken a bunch of pics to document the process of finding the OVP relay and testing it and will fully document the whole troubleshooting and testing process of getting the A/C blower working again (I'm currently an unemployed technical trainer and computer consultant so documentation for knowledge bases is what I do).

Thanks in advance for whatever informed feedback or info you can give me.