‘91 940 Turbo
 

I hate to post another thread on such a common issue, however I haven’t found anything thus far to clear things up, so here goes:

I’ve never had functioning HVAC in my 940 and thus, recently, I removed the blower motor and tested it by connecting two wires to the blower motor and the ends to the battery and got nothing. I went to the junk yard and retrieved a blower motor from a ‘90 n/a 940 sedan, went through same procedure and it whirred to life! Home free? Not quite. I installed the junk yard part and again, had no airflow from any vents at any speeds. I checked to see if the plug had any power getting to it, and low and behold it did not.
So I checked the fuses, none blown. I read about a vaccuume line that runs through the firewall, but I assume that in order for that to be the problem, the blower motor must have power to it. I also understand that if the blend door is at fault, the fan will work intermittently or only on speed four. Finally, I read about some confusion regarding a relay behind the glove box, however I’m fairly confident that there are no relays in this system.

Any assistance appreciated!
Again, I hope I’m not wasting anyone’s time by creating a new thread regarding this issue if this information already exists.

There is no 1990 940, 1991 is the first year...
Is your 940 an SE or a plain 940? They have completely different HVAC systems.

on the 740/940 (non-SE) there is a resistor brick near the fan motor, and the front panel fan switch, which is labeled like off, 1,2,3,4 or ssomething, each setting goes to a different 'tap' on that resistor block. When that resistor block dies, it usually cooks and looks blackened/charred, and will often still work in the highest position, but not in lower settings

as lev says, the 940SE (91 only, always a turbo) is a very different beast, and has the electronic climate control system from a 760/960, and has an electronic power module instead of the resistor brick. the climate control system fan control has an AUTO position, and the temperature knob is marked in degrees instead of just cold----hot (or blue.....red). pretty sure the SE uses a completely different fan motor, too.

Apologies, the junk yard part came from a 740, I mistyped. But mine is a non-se '91 940 turbo, so it would have a resistor block, however there is no current getting to the blower motor at any speed and therefore does not work on any of the speeds. Should I still still check the condition of the resistor block or would that be a waste of time?

check the voltage from ground from each of the resistor leads, ONE of them should have voltage at any given speed setting. if not, then either the speed switch is broken, or the speed switch isn't getting any power itself

ok, looked it up, the switch has 0 (off) and 5 speeds (1-5). 5 goes to the same end of the resistor block the motor is connected to. 1 goes to the opposite end of the resistor block, and 2-3-4 go to the various middle taps. the power for the switch comes from Fuse 16 in the main fuse panel behind the ash tray. fuse 16 gets its power from the ignition switch pin "X", on in accessory and run

What about the controller, in the dash? They often go bad. Have to resolder the connectors on the circuit board...

the fan speed doesn't go through the controller board, such as it is. its a rotary switch with 5 outputs that goes directly to the resistor block.

now, for sure, its a good idea to check for power going into fan switch pin 1 (with the ignition switch on or in accessory). full speed is fan switch pin 2, so with the switch at '5', pins 1 and 2 should be connected