AC COndenser Fan - Wiring Help!!

Sunroof · 02-10-2003, 05:06 AM

I removed my front AC condenser blower motor and tested the circuit to see if any power gets to the motor. Zilch, nada, nothing!!
Its that two prong mated fitting (one brown wire and one green-white wire). I do not see it going to the fuse box.

I have no idea where the circuit is on this dealer installed factory unit. Does the fan stay on everytime the compressor goes on?
Is the blower activated by the switch for the fan for the passenger compartment? Does the power come off the relay or connection in the smugglers box? This is frustrating, but probably a simple cure............I do not know what the amps are for this small 12V motor as well.

I am at a loss and wish to avoid going to a mechanic for an expensive rewiring if I can simply make two connections for the motor, BUT WHERE? If anyone can suggest even the proper jury rigging that would help. I think the big issue for me is how the motor gets activated since it seems that the fron AC condenser needs the cooling more when the car is at a stop then not.

By the way, the 911 is a 1973.5T.

Thanks
Bob

jeff m · 02-10-2003, 10:37 AM

Bob,
Here is a diagram that may help http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg
One thing that I have in my toolbox is a relay with 30 and 87 shorted out.
When plugged in it looks like an operated relay to the circuit and has saved me lots of time faulting my cars (and my buddies cars)
I'm not convercent with the P A/C but beware of hi and low switches if it has them. These things can throw you!
Hope I've been some help, if not at least I've given you a bump.
Jeff
911T

stormcrow · stormcrow's Garage

Bob,

The condenser blower will come on when the fan switch is turned on. Looking at the wiring diagram there is a relay for the cooling fan motor (which I think is the Condenser fan motor) and one for the evaporator fan motor. The switch brings both on. The evaporator fan ac relay is powered by the switch for L-M-H speed. The switch also controls the relay for the cooling fan motor which is a single speed and the compressor clutch.

A couple things you need to check. Does the cooling fan come on when the switch is turned on? Does the compressor clutch engage when the switch is turned on? If not, then I would check the relays and the fuses to the relays.

Hope this info helps

Steve

"A Porsche does more then just go fast in a straight line"

Sunroof · 02-10-2003, 05:37 PM

Thanks Steve.............
That switch that is nested in the knee level AC vent area looks like something Alexander Graham Bell used for his first phone switch!!!!! It does have five wire fittings and does turn the compressor and interior blower motor on the same time. Luckily Ellis has 'em for $47.00, but its a Stuttgard import. If the AC front condenser fan does operate from this switch as the diagram shows, maybe a new switch is in order.

Regards
Bob

targa80 · targa80's Garage

Just out of curiosity did you apply 12 volts to the fan motor to make sure it is still functional. The one that was in my car is frozen solid, the squirel cage won't spin by hand.

Sunroof · 02-11-2003, 05:04 AM

Pat...
I did try the motor with alligator clips on a fresh battery. No deal. It too was frozen up. In fact I had to saw the squirrel fan off and pound the remaining motor shaft out. Its toast!!

I tried everything short of replacing the actual AC switch to get power to the blower motor connector. Nothing. I would hate to chase this thing til my wallet runs dry, but I will replace the switch itself since its getting worn.

I am up for any ideas, suggestions, etc.

Bob

targa80 · targa80's Garage

Bob:

As posted by jeff M the schematic for the AC is the same as is in my 80SC. I would suggest that the wiring might be the same for your dealer install. The following is a description of the operation of the circuit as I see it. http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg

The cooling fan motor is fed by a wt/gn wire. The cooling fan motor is the line going to the fan in the trunk for the front condenser. The evaporator fan is fed by a re/wt wire. The evaporator fan supplys cooling air to the interior and is controlled by the AC three speed switch. The speed of the fan is controlled by the addition of the coil resistors into the fan circuit. The coil resistors are located behind the connector in the passenger foot well.

With the engine running power is fed from the ignition switch to first of two relays. With the first relay energized it feeds power from fuse 20 (trunk fuse panel) thru the relay closed contact to the AC switch (contact C). When the AC switch is turned on power from the AC fan switch (contact C) is fed to (contact B) which supplys power to the temp switch. The temp switch is normally closed (opens when interior temp is reached) feeds power to the AC clutch assembly and also to second of 2 AC relays. the second AC relay is energized and closes its contact to feed power from fuse 20 thru its closed contacts to the cooling fan in the trunk.

If when you turn on the AC the clutch engages then you should have power to the second relay. This would allow power from fuse 20 to be fed through the second relay to the cooling fan in the trunk.

This is where I would start troubleshooting using a multimeter to test for voltage or continuity between each component's wiring.