911 SC -- AC blower (over condenser in smugglers box) -- is it dead or not?!

[white-tt]

Hi all,

I have an '83 911 SC.

Since I bought the car 3 years ago, the AC blower fan (center vents, NOT the fresh air fan) has squeaked and clicked. Well, it flat out didn't turn on the other day. After leaving the AC "on" for a couple minutes, smoke creeped into the cabin from the center vents (AC vents). Dead fan, then?

So, I pull the AC blower fan out from the smuggler's box (PITA), and it looks perfect. It doesn't have any obvious play about the shaft. It does seem a little difficult to rotate, but not "notchy". Just tight-ish. Easy enough to spin by hand, but no way would it continue to rotate without some small force.

So I hooked it up directly to a 12V car battery, and it spins! Not fast... but it DOES spin. So before I replace it, how can I know for sure it is bad?! Should the squirrel-cage spin more freely? Where did the smoke come from if the motor looks fine? Is there something else that could be smoking through the vents?

side question: I have a spare fresh air blower fan (bought the wrong one at a swap meet - D'oh!). The motors wouldn't happen to be interchangeable, would they? Does our host sell the motor I need? I couldn't seem to find it.

Thanks all!

[Bob Kontak]

In Pelican's parts list

Pelican Parts - Product Information: 911-624-899-00-M207

Griffiths sells a high output blower motor direct. Big price difference. Not sure if they are the same part but from pics looks like the PP blower has add'l hardware for mounting. A few phone calls would be prudent.

911/930 Kuehl Wirbelsturm Evap Blower Motor 70-85 911 evaporator blower motor, 930 evaporator blower motor, 901-624-901-00, 90162490100, 901 624 901 00, 901.624.901.00,911-624-899-00,911 624 899 00,91162489900,911.624.899.00 [911930KuehlWirbelsturmMo

Fresh air blower is not the same motor.

[wwest]

Originally Posted by white-tt

Hi all,

I have an '83 911 SC.

Since I bought the car 3 years ago, the AC blower fan (center vents, NOT the fresh air fan) has squeaked and clicked. Well, it flat out didn't turn on the other day. After leaving the AC "on" for a couple minutes, smoke creeped into the cabin from the center vents (AC vents). Dead fan, then?

So, I pull the AC blower fan out from the smuggler's box (PITA), and it looks perfect. It doesn't have any obvious play about the shaft. It does seem a little difficult to rotate, but not "notchy". Just tight-ish. Easy enough to spin by hand, but no way would it continue to rotate without some small force.
The squirrel cage should turn VERY freely. Clean and lube the porus bronze bushings/bearing at each end of the motor shaft.

So I hooked it up directly to a 12V car battery, and it spins! Not fast... but it DOES spin. So before I replace it, how can I know for sure it is bad?! Should the squirrel-cage spin more freely? Where did the smoke come from if the motor looks fine? Is there something else that could be smoking through the vents?

A good test would be to measure the current flow while connected directly to the battery. Someone here will know what it should be.

side question: I have a spare fresh air blower fan (bought the wrong one at a swap meet - D'oh!). The motors wouldn't happen to be interchangeable, would they? Does our host sell the motor I need? I couldn't seem to find it.

Thanks all!

Your A/C operates in recirculate mode by design. The primary cabin air intake is behind the passenger floor footpanel and there is a HIGH POWER resistor set used to control/limit the lower speeds, mounted within the inlet. If the blower motor stalls then the resister set will "click" open as a result of current flow HEAT getting too high, then close as things cool off, etc, etc.

Don't forget to check for mouse, nests, droppings, even baby mice.

[skrufy]

Blow out any dust, etc with compressed air, then lube the bushings really well- you may be able to save that fan motor-....... for a while.

Tim

[kuehl]

At 12vdc, providing at least 12-15 amps, with the blower fan attached to the motor, it will spin quite fast, fast enough to fly out of your hand. Hence it sounds like your motor is shot.

Best upgrade with detailed instructions is this one hands down:

Pelican Parts - Product Information: 911-624-899-00-M207

[wwest]

$375.00 is a LOT of DIY modivation.

Disassemble the motor, use emery cloth to burnish the commutator, replace the brushes, clean and lube the sleeve bearings/bushings.

[kuehl]

edited

[wwest]

Originally Posted by kuehl

What the host wishes to charge is up to them, the reader can google the motor
other places naturally, however

the Kuehl motor puts out over 30% more air

More SNAKE OIL, expensive SNAKE OIL.


, has bearings rather than cheap bushings
so it will last longer and its an easy upgrade.

Yes you can try to clean the commutator and replace the brushes
however lubricating a bushing that is worn won't replace or reshape the worn metal.... that is
all a temporary fix.

"modivation", sounds like a idiosyncratic western language, lol,
keep digging wild west, keep digging deeper,

Given the inlet, outlet restrictions to airflow, plus the resistance to airflow by the evaporator itself, I rather doubt that a 30% improvement could be had in actual use.

Proof...?

[white-tt]

Originally Posted by Bob Kontak

In Pelican's parts list

Thank you for the links! I will consider them if I can't get my existing fan back running

Originally Posted by wwest

Your A/C operates in recirculate mode by design. The primary cabin air intake is behind the passenger floor footpanel and there is a HIGH POWER resistor set used to control/limit the lower speeds, mounted within the inlet. If the blower motor stalls then the resister set will "click" open as a result of current flow HEAT getting too high, then close as things cool off, etc, etc.

Don't forget to check for mouse, nests, droppings, even baby mice.

Thanks for the explanation and tip. Per your suggestion, I checked back there. It looks like it hasn't seen a single photon in 30 years (probably hasn't). Brand new. Nothing in there as far as I could tell. The resistor pack looks brand new as well.

Originally Posted by skrufy

Blow out any dust, etc with compressed air, then lube the bushings really well- you may be able to save that fan motor-....... for a while.

Tim

Thanks, I am planning on giving this a shot.

Originally Posted by wwest

$375.00 is a LOT of DIY modivation.

Disassemble the motor, use emery cloth to burnish the commutator, replace the brushes, clean and lube the sleeve bearings/bushings.

Agreed. I would really like to avoid that $375!!

As much as the Kuehl motor seems like a nice way to go.. I have to wonder.. the inherent cooling of the AC system will not be changed by the blower, correct? I haven't looked at refrigeration cycles since my last thermo class a few years back, so I don't remember a lot. The big gain of the supposed 30% MAF improvement would only serve as forced convection when the ducts are aimed at the passengers. Living in california, I don't think I need the extra flow anyway. I will avoid spending on this project if I can. I have other goodies I want, and I set a very specific budget for the old girl. You'll see me at swap meets if I can't revive this AC fan.



other note: stuck a multimeter on the fan plug from the car. With the AC turned on, it is getting its full voltage, so all the wiring up to the fan looks good. I think it's just tight on the shaft. I'll post my luck at reviving it from the dead

Thanks everybody so far! You've been very helpful

[wwest]

30% more system airflow will only help if the evaporator core temperature doesn't rise accordingly(***). Provided the evaporator temperature remains fairly low the big gain would be quicker initial cooldown of the cabin.

Most of us "turn" to more moderate system airflow as/once the cabin cools.

*** In my opinion the major shortcoming of the Porsche factory air of this era is the lack of adequate condensing capacity. Follow Porsche's lead on this, the very first substantive improvement they made was to add the condensor/blower behind/under the front bumper. And then there is the aftermarket providing various versions of additional condensing capability.

So, provide enough condensing capacity and the evaporator core temperature might well remain (more) stable as the rate of airflow rises.

[white-tt]

Hey wwest,

how did you get the motor apart? I've got it out of the plastic housing, but I'm not sure how to split it. There's no bolts/clips in sight.

[wwest]

Originally Posted by white-tt

Hey wwest,

how did you get the motor apart? I've got it out of the plastic housing, but I'm not sure how to split it. There's no bolts/clips in sight.

Been awhile..pictures of yours to jog my memory?

[white-tt]

pictures attached:

[white-tt]

The motor looks to be in OK shape, but it definitely has some resistance. I am not confident that even if I could get it apart that I would be able to truly revive it. There is a small motor repair shop 20 min away. I'm going to drop by tomorrow and let the pros revive this old hunk of metal. I can't imagine it will be too much $.

[wwest]

Originally Posted by white-tt

The motor looks to be in OK shape, but it definitely has some resistance. I am not confident that even if I could get it apart that I would be able to truly revive it. There is a small motor repair shop 20 min away. I'm going to drop by tomorrow and let the pros revive this old hunk of metal. I can't imagine it will be too much $.

Use a small cold chisel to drive back (gently) the "sweges" holding the front end cap in place.

But first I would use WD40 to clean/rinse both shaft bearings and then soak the bearings with light machine oil (10 weight) before and while the motor is running. A lot of end-play would indicate a need for a thrust washer replacement. I would replace the commutator brushes simply as preventive measure.

The pictures seem to indicate that the brushes are on their last leg....

[wwest]

Great pictures!

[white-tt]

Well, the local shop was completely unhelpful. After a 25 min drive each way, I am no further. I called before and they said they can take a look and it shouldn't be too hard. After I got there, he took a look, seemed to be very confused and said it would take him a while so I'd have to come back in a couple weeks. Great.

I called Bosch, but they said the motor was only made specifically for Porsche, so only Porsche sells it.

I will be looking for good-condition used motors. We'll see what comes of that.

In the mean time, I guess it's back to breaking it apart. I'll get a chisel. Thanks for the help, wwest!

[86 911 Targa]

Originally Posted by white-tt

Well, the local shop was completely unhelpful. After a 25 min drive each way, I am no further. I called before and they said they can take a look and it shouldn't be too hard. After I got there, he took a look, seemed to be very confused and said it would take him a while so I'd have to come back in a couple weeks. Great.

I called Bosch, but they said the motor was only made specifically for Porsche, so only Porsche sells it.

I will be looking for good-condition used motors. We'll see what comes of that.

In the mean time, I guess it's back to breaking it apart. I'll get a chisel. Thanks for the help, wwest!

Here you go:

Porsche AC Evaporator Fan HVAC Blower Motor Bosch 0130007002 New | eBay

The only "tricky" part in replacing these motors is removing the old one without damaging the allen set screw.

Good luck,

Gerry

[white-tt]

Originally Posted by 86 911 Targa

Here you go:

Porsche AC Evaporator Fan HVAC Blower Motor Bosch 0130007002 New | eBay

The only "tricky" part in replacing these motors is removing the old one without damaging the allen set screw.

God luck,

Gerry

Isn't that the motor for the heater fan?

Do you mean the allen set screw on the squirrel cage? Mine came loose quite easy. I hope I didn't break something. It seems to screw back on just fine.

[86 911 Targa]

Originally Posted by white-tt

Isn't that the motor for the heater fan?

Do you mean the allen set screw on the squirrel cage? Mine came loose quite easy. I hope I didn't break something. It seems to screw back on just fine.

not according to the posted description.