Blower Fan replaced - still a strange issue

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08 May 2015 16:52 - 08 May 2015 16:54 #18266 by mm928
Hey all,

I just finished a 2 part upgrade. New blower fan replacement and a re-conditioned HVAC head unit.

My old blower was working but has been squeaking for the majority of 2 years so I decided to upgrade. Unfortunately, on the way to get that put in, the Head unit stopped altogether. Then it started back up a few minutes later and worked fine until I got to the repair shop.

Since you need the head unit to send the start call to the blower, and we really wanted that part to be working before we did the blower upgrade, I ordered a reconditioned Head unit from Roger. Looks great, works great, bench tested etc. Well my mech got everything going, then he told me the fan took a minute or two to come on with him, then worked fine. Started right up for me at his house, then later when I started it up to leave work, same thing happened to me....2-3 minutes later, I tuned it off/on and voila! Worked fine all the way home.

Based on our understanding of the related issues while trouble shooting with things, it seems we have eliminated both the blower and head unit (problem has been seen inside the unit, and both are now new, sort of). Also, when it does not work, there is no blower whatsoever, you do not hear the internal flaps in the dash moving when you turn it on like normal, and if you put it on defrost there is nothing either. We know it is supposed to run on full when on defrost by design.

It just happened today, so I am going to drive it some this weekend and Monday and try to see what kind of other indicators and characteristics can be seen.

It sounds like there is something going on that essentially makes the head unit stop working or have no power or send no signal to the blower, compressor etc.. I do have a spare relay in case that is doing weird things. But before I pull that, I thought I would post to see what other may say.
I guess it could be wiring or a switch somewhere along the way, but not sure where to try and start.

Anyway - I will report back in a couple of days to see if I can add any more info.

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -
Last edit: 08 May 2015 16:54 by mm928. Reason: added text

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08 May 2015 21:06 - 08 May 2015 23:21 #18267 by billvvSU
Replied by billvvSU on topic Blower Fan replaced - still a strange issue
Relay IV is energized when the ignition switch is in 'RUN'. If the cigarette lighter works, that relay has power at its coil (as long as the wiring in the CE panel is OK). The output of that relay provides power to the HVAC control switch via pin G18 of the CE, which provides power to the flap solenoids.

I'd try that one first. Weak coil, maybe. As the car runs and charges the battery and system voltage raises enough to let the coil decide to pull in the relay. Maybe.
Last edit: 08 May 2015 23:21 by billvvSU.

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08 May 2015 22:17 #18268 by mm928
Hey Bill thanks, good info to know, I had not seen that. I have also learned that fuse #9 apparently provides some power to the head unit, in a back handed way, even though it says it is for mirrors etc. So let's see what it does tomorrow on a couple of runs.

I will report back

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

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09 May 2015 19:28 #18269 by mm928
FIXED! Fuse #9

HVAC not run at all this AM, so I pulled fuse #9 and it fell apart in the needle nose. But, it was not popped in the middle like normal, it had broken at the top and was blackened there. So it would have been hard to see anyway.
The fuse sheet does not say #9 is the blower but it does say Air conditioner and Remote mirrors. Tried Remote mirror while driving... did not work - aha moment occurs.
Put in a new 8 amp #9 and it worked immediately and all day afterwards.

So looks like it was failing and did have some corrosion on the bottom as well which might explain the heating up and driving making it work after a while. But it would not run at all today.

So I did learn a lot by all this odd coincidence of something breaking just as we were going to work on another part that was related to it. The replacement motor from Roger is indeed smooth, quiet and has a really good airflow, even on #1 setting. The rebuilt HVAC head really lubricated well and seems to be working great. Looks good as well for a 32 year old piece of equipment.

Note however, early models likely need some housing changes/tweaks to get the replacement motor to fit right. But it will work if you are careful and good with electrical tape :)

Put this one to bed!

Thanks Bill

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

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10 May 2015 12:23 - 10 May 2015 13:40 #18270 by billvvSU
Replied by billvvSU on topic Blower Fan replaced - still a strange issue
Are you sure it wasn't fuse 6? Fuse 9 is 'telephone' according to Alan's diagram. Was your car imported from Japan? That might explain the difference.

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Last edit: 10 May 2015 13:40 by billvvSU.

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10 May 2015 13:30 - 10 May 2015 13:34 #18271 by mm928
Probably just the difference between an 83 and 89,





Never noticed that in the chart before,,,I am sure there are probably others,

MM

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

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Please log in or register to see it.

Last edit: 10 May 2015 13:34 by mm928.

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10 May 2015 13:42 #18272 by billvvSU
Replied by billvvSU on topic Blower Fan replaced - still a strange issue
Ah. thought your car was an '89 for some reason.

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