Diagnosing a heater fan / blower issue

Colltech

Colltech

'85 and '83
Recently, the heater blower fan on my 1985 X stopped working. Its an AC car with a 3 speed fan switch. My first thought was a fuse but the fuse is fine and the stop light switch and hazard lights all work (same fuse). That leaves only the switch itself, the fan motor, or the wiring between them as the possible problems. I’ve pulled the instrument binnacle and the radio surround to get at the switch and the plug that connects it. Before I go through the pain and hassle of dropping the heater box, I’d like to see if I can try to power the fan motor by shorting the appropriate wires in the white plastic connector to the switch.

Here’s the question – can this be done and if so, which wires should I short? None of my manuals or documentation show the correct wiring codes/colors that I am seeing on this connector – I suspect they are for older or non-AC cars. Anyone know?

Here is a picture of the connector:
20161212_235944.jpg


Thanks in advance for any help!

Ed
 
The contact with brown and black wires to it is the ground connection. Shorting the white wire to the black & brown should give you full fan speed. Red to black & brown should give you medium fan speed, and gray to black & brown should give you the slowest fan speed.

If the full speed works, but neither of the reduced speeds do, check the resistor in the left cowl area.

Also check continuity between black & brown and chassis ground.
 
OK, tried jumping the contacts and still could not get the fan to spin. Since its unlikely that all three of the power wires are severed, I think I can assume that the motor has either lost ground or that its simply fried. I am going to pull the dash vents and see if I can spin it by hand in case its "stuck" for some reason (even though I don't even hear it humming).

Short of pulling the heater box (dread that), any other good suggestions I might be missing?

Ed
 
If you have a multimeter handy, you could do a few more tests before extricating the fan:

Remove the A/C blower relay (different from the A/C control relay).
Measure continuity between the socket for relay terminal 86 and chassis ground. With any HVAC button pressed except "Off", there should be continuity to chassis ground.
Measure voltage between the socket for relay terminal 85 and chassis ground. There should be battery voltage with the ignition switch in run or start.
Measure voltage between the socket for relay terminal 30 and chassis ground. There should be battery voltage at all times.

You could also try substituting a known-good relay on the off chance that the relay is bad.
 
Unfortunately, the only way you are even going to touch that fan is with heater-AC box removal. So do all the electrical tests thoroughly first. But it is likely that the motor is dead, especially if you need to bump it to get it going. I would point you to the threads with my heater box rebuild, but I just realized that all my links to those articles are no longer working due to the new and improved site.
 
ng_randolph said:
If you have a multimeter handy, you could do a few more tests before extricating the fan:

Remove the A/C blower relay (different from the A/C control relay).
Measure continuity between the socket for relay terminal 86 and chassis ground. With any HVAC button pressed except "Off", there should be continuity to chassis ground.
Measure voltage between the socket for relay terminal 85 and chassis ground. There should be battery voltage with the ignition switch in run or start.
Measure voltage between the socket for relay terminal 30 and chassis ground. There should be battery voltage at all times.

You could also try substituting a known-good relay on the off chance that the relay is bad.
Click to expand...
ng_randolph said:
If you have a multimeter handy, you could do a few more tests before extricating the fan:

Remove the A/C blower relay (different from the A/C control relay).
Measure continuity between the socket for relay terminal 86 and chassis ground. With any HVAC button pressed except "Off", there should be continuity to chassis ground.
Measure voltage between the socket for relay terminal 85 and chassis ground. There should be battery voltage with the ignition switch in run or start.
Measure voltage between the socket for relay terminal 30 and chassis ground. There should be battery voltage at all times.

You could also try substituting a known-good relay on the off chance that the relay is bad.
Click to expand...


Bjorn,

Thanks for the advice. Last night while trying to spin the fan by shorting the switch I noticed a "click" from a relay every time I tried. By "feeling" which relay was clicking, I isolated the correct relay and swapped it with another. Still no luck.

Ed
 
LarryC said:
Unfortunately, the only way you are even going to touch that fan is with heater-AC box removal. So do all the electrical tests thoroughly first. But it is likely that the motor is dead, especially if you need to bump it to get it going. I would point you to the threads with my heater box rebuild, but I just realized that all my links to those articles are no longer working due to the new and improved site.
Click to expand...

Thanks Larry, Actually, I posted a heater box rebuild as part of my massive 83 X restoration post. So I've done one of these before and was very much hoping to NOT have to do another!

https://dl.dropboxusercontent.com/u/3359580/Ed Taylor X1:9/Ed Taylor How I came to buy an X1-9 s.pdf


Ed
 
Ed, O.K., so you know the horror then! It took me two days- two days!- to get mine back in when I last removed it. I fiddled and finagled, and then fiddled and finagled some more, and it finally lined up. Don't know what finally did it, but I was just glad it lined up.
So, I have not tried it, but you don't suppose there is any hope that just dropping the lower shell would be of any help do you? There would still be a lot of work; the heater core would need to be disconnected and all sorts of other stuff. But if it was even remotely a chance that the motor could be accessed with a little less work, that would be a major help.
 
LarryC said:
Ed, O.K., so you know the horror then! It took me two days- two days!- to get mine back in when I last removed it. I fiddled and finagled, and then fiddled and finagled some more, and it finally lined up. Don't know what finally did it, but I was just glad it lined up.
So, I have not tried it, but you don't suppose there is any hope that just dropping the lower shell would be of any help do you? There would still be a lot of work; the heater core would need to be disconnected and all sorts of other stuff. But if it was even remotely a chance that the motor could be accessed with a little less work, that would be a major help.
Click to expand...
I've thought about trying to drop the bottom half but if its really the fan motor itself (which is becoming more likely), I'll just end up pulling the whole thing anyway. Its sort of a "death by a thousand cuts" thing at that point.

Truth is, I would have already dropped the heater box but I'm dealing with a left rotator cuff injury which makes using my left arm in the ways needed impossibly painful! You just really can't get at this thing with one good arm! Maybe I can entice Dennis to come over and help.

Ed
 
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