AC Fan does not work at all on 1987 Mondial 3.2

(This is part of a PM I rec'd from OCFerrari -- I'm posting it here because I need to use jpeg/attachments and can't do so in a PM.)

OCFerrari said:

...87 Mondial cab.

My ventilation fan doesn't work. I see in the threads it is fairly common for it to only work on "high," but mine does not work at all.

I think my AC compressor does kick in.

I've checked for 12V at the W connector, it checks correctly (12V with ignition on, 0 when off). My W connector is pristine white, no burning or discoloration at all (the car only has 6k miles).

I ran the checks on the relay on the PCB.

ignition key "on"
tab 30 is still at +12V relative to ground - This checks out.
tab 87 is at +12V relative to ground - this checks out


the voltage between tabs 85 and 86 is +12V (or -12V depending on which probe of your voltmeter is on which tab) - this one, I'm not 100% sure what you are saying. I am using a 12V test light. Are you saying to run the test light between 85 and 86? I haven't done that, but I think it would check out.

I switched the relay with another 113 relay. No change.

The 3 black relays on the AC unit (I think they call it the condensor unit) under the dash - all three click when I turn the fan switch to "almost high" (about 90%). I can hear a tiny fan go on under the dash, I think, which I believe is a fan on the air temp sensor.

Thoughts on what to test next?...

 

OCFerrari -- I only have the wiring diagram for a euro Mondial 3.2, but I would be somewhat surprised if the AC system was different if yours is a US version, but:

1. Please confirm what version Mondial 3.2, and

2. If you can get to connector C12 on the AC unit itself -- please confirm/deny if the wire colors and pin count are the same.

If so, we can go from there.

Getting +12V at the large+small MN (brown/black) wires exiting the w connector (key "on") indicates everything on the fuse-relay board is OK, and the problem is either on the AC unit electrics or the blower motor itself.
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OK, how I would start is:

1. the large 2.5 MN (brown/black) wire is the same one as the MN wire leaving the "w" connector -- turn the key "on" and confirm that this wire goes +12V (relative to a good ground) at the C12 connector.

2. If it does, (still with key ""on" and everything plugged in), using a jumper wire, connect the 1.5 VR (green/red) wire to a good ground -- if the blower motor runs full speed, that's a good sign that the blower motor is OK, and something is wrong with relay "c", or what's controlling relay "c". When you turn the speed control knob to "full speed", the relay "c" should actuate/click -- you did check the 1A fuse in the speed control ECU yes? You can also connect your test light between the MN wire and the CG (orange/yellow) wire -- when you turn the knob to "full speed", the test light should illuminate if the speed control ECU is working OK. If the blower motor doesn't run full speed with the jumper in place = bad blower motor.

Try some of that, and report what you find please.

 

That's good.

Not good -- either the fan motor itself is dead, or (if you are lucky) there is some connection fault between the C12 connector and the fan motor (you can see from the schematic that the MN wire should be directly connected to one brush of the motor and the VR wire should be directly connected to the other brush of the motor). Sadly, I'd have to conclude that the fan motor is toast, but the next test level would be to do the same thing, and measure the voltage directly at the fan motor brush connections -- if it's still +12V there, but the fan motor doesn't run, no option but to get a new fan motor.

This shows correct (command) operation of relay "c" when requesting "full speed" -- but even if relay "c" was bad (i.e., it "clicked", but it really wasn't connecting terminal 30 to terminal 87 when energized), the fan motor still should've ran when you grounded the VR wire.

Same as previous.