A/C fan squeal and then it died
 

My A/C fan has always had a periodic squeal on the 2 slowest speeds but not on the high speed. The other day while on the high speed it did one squeal and then cut off. The condenser nor fan cut on now. I have check the fuses and relays.
Any suggestions?

it's called "death rattle" new or rebult fan is in order. It's the bearings/bushings that fail on these. You can rebuild them yourself.

Putting direct 12v to a siezed fan is a good way to first ruin it totally and second to possibly start a fire.

It squeeled because it was freezing up inside and now you get to have it removed and overhauled if possible or buy a new one. Next time it even starts to make a noise like that, fix it then and maybe you can salvage the fan. Doubt that this one will make it...

Joe A

What am I missing here? I haven't looked at the wiring schematics for the AC system, but if the fans are unfused how can one blow a fuse? :confused:

What you are missing here is that the squeeling is usually froim the bearings siezing in the fan. Once the fuse for the fan blows it usually a lump of hard metal called a boat anchor!

Seriously guys, many 911's have been totaled by the front condensor fan siezing and the circuit not having a fuse in it, and then the fan finally gets tired of the abuse and starts a fire, burning the car up.

There was a Porsche factory mod going to the front fan that introduced a fuse in the circuit. Some cars may not have this mod, and if so its just a matter of time.

When my front condensor fan bit the dust it blew a 25 amp fuse. I don't know about the AC fan being fused but there is a relay that can go bad.
You can test your condensor fan with 12V but not the AC fan if it has seized.

Probably done.

I had my fresh air fan crap out many years back on a Massachusets to NJ drive in a similar manner; Made a noise and gave me a nice spew of smoke and burnt smell out of the vents upon its death. I wouldnt keep it turned on or apply 12v to it. Time to replace it.

It sounds like you mean evaporator (ac) motor is giving you issues. You can test it. Open the front trunk, lift up the carpets open the 'smugglers trap door', locate a black wire harness with a white 'T' shaped connector (molex), unplug it, the end the leads into the black evaporator box will have two terminals, red is positive and brown is negative, from your battery or using a battery charger apply 12 volts positive to the terminal with the red wire and negative to the terminal with the brown wire. If the fan does not operate either your fan blade has slipped down on the shaft of the motor and is scraping on the motor's support plate (plastic) or the motor is shot. You can either buy an OEM motor such as this:
Pelican Parts - Product Information: 911-624-899-00-M100 or a Kuehl Hurricane motor which puts out 30% more air, here:
911/930 Kuehl Wirbelsturm Evaporator Blower Motor 911 & 930 , installation article here:
http://forums.pelicanparts.com/porsche-911-technical-forum/472352-anyone-here-1986-done-kuehl-wirblesturm-hurricane-evap-motor-upgrade.html

Occasionally your fan speed switch fail, you can find them here:
Pelican Parts - Product Information: 911-613-243-00-M100
or if you want to upgrade to a full variable speed switch you can find them here:
Kuehl Evaporator Fan Variable Speed Controller Porsche 911 & 930

The AC schematic is here,
http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg

Other reading materials:
http://forums.pelicanparts.com/porsche-911-technical-forum/397009-c-upgrade-project-starts-tomorrow.html


PM if you need more help.

On our '86, fuse #2 (25A) is used for the A/C.

We use fuse #2 for the condensor motor and fuse #3 for the evaporator motor to "share" the current load thereby preventing this.

http://forums.pelicanparts.com/uploa...1279810732.jpg

However, the evaporator and condensor fan(s) were not individually fused.

As per Kuehl suggestion(s) evaluate the issue with your evaporator fan.

Applying a momentary 12V to your fan will not damage the motor.

I serviced our footwell blower motor as per a Pelican post.


Then, here are some additional recommendations.

1. Fuse your front condensor fan @ 10A.

http://forums.pelicanparts.com/uploa...1279809397.jpg

2. Purchase an fused evaporator relay for our host.

http://forums.pelicanparts.com/uploa...1279811102.jpg

3. Fuse your dash lights per a previous post @3A.

http://forums.pelicanparts.com/uploa...1279809704.jpg

4. Fuse your footwell blower motors @ 10A.

http://forums.pelicanparts.com/uploa...1279810246.jpg

5. Install a headlight relay kit from our host.

http://forums.pelicanparts.com/uploa...1279810403.jpg

Good luck,

Gerry

pm me as required.