95 993 condenser and oil fan issues

[jmarch]

When I switch on the A/C, the condenser fan does not turn on. I have also noticed that the oil cooler fan is not running at temperature and the fan to cool the engine after the car is turned off does not run either. I have swapped relays and there is no difference. The electrical schematic points to the A/C control unit. Any help on this is greatly appreciated. Is there any way to test the A/C control unit or a place to send it out? Is there something I am missing (fuses are all fine also)?

[bazar01]

Originally Posted by jmarch

I have swapped relays and there is no difference. The electrical schematic points to the A/C control unit. Any help on this is greatly appreciated. Is there any way to test the A/C control unit or a place to send it out? Is there something I am missing (fuses are all fine also)?

You need to check first to make sure the relay is getting a 12V control voltage to the coil (term 85 and 86). If there is no control voltage, then the CCU is suspect.

[jmarch]

Thank you for your response. I checked terminals 85 and 86 by having the relay plugged partially in. I had a reading of 11 volts. I checked terminal 30 and it had the full 12 volts. What would you suggest next?

[bazar01]

Originally Posted by jmarch

Thank you for your response. I checked terminals 85 and 86 by having the relay plugged partially in. I had a reading of 11 volts. I checked terminal 30 and it had the full 12 volts. What would you suggest next?

That's good.

Next, pull out the condenser fan (R14) relay.
On the relay socket, put a jumper wire on terminal 30 (12V) and 87 and see if the fan runs.

[jmarch]

Thank you again. When I jumped across terminal 30 and 87 on both the a/c and oil cooler terminals, the fans on both ran. What next?

[bazar01]

Originally Posted by jmarch

Thank you again. When I jumped across terminal 30 and 87 on both the a/c and oil cooler terminals, the fans on both ran. What next?

Pull the condenser fan relay again.
Put a jumper across terminals 30c and 87c and see if the fan runs in slow speed.
Do this also on the oil cooler fan.

[jmarch]

Greetings. The fan does not run for either when jumped. There is 12v at the 30c terminal. There is also a 12v reading when I used the tester to jump across from 30c to 87c . Any significance? What next? Thank you.

[jmarch]

I went back to the schematics and see that the jumper from 30c to 87c is routed through a resistor for the condenser and oil cooler. Does that mean they are defective? From what I have read, they are part of the motor wiring harness. Is that correct? Thanks for the input. Am I getting too far ahead of myself?

[bazar01]

Originally Posted by jmarch

Greetings. The fan does not run for either when jumped. There is 12v at the 30c terminal. There is also a 12v reading when I used the tester to jump across from 30c to 87c . Any significance? What next? Thank you.

Good job jmarch!

The fan resistors are open. They are a little hard to reach. They are right there at the heat exchanger fan motors. They are round ceramic 0.6 - 0.8 ohm power resistors.
If you don't have replacement resistors, I would just join the two wires going to the resistor terminals for now and test the fan operation. Without the resistors, you will lose the slow speed operation. But at least you can test if the CCU works and operates the fans.

Good luck!

[jmarch]

The condenser fan is running when the resistor is jumped. I have not tried the oil cooler fan yet but assume that it is the same situation. Getting to the actual resistor is beyond PITA but it was a good change to clean the condenser. Thank you so much for your guidance. I hope I can return the favor in the future by paying it forward.

[jmarch]

I have one last question, does the resistor need to be re-mounted on the same spot? Is it there for cooling purposes or to monitor the amount of heat? Can it be mounted elsewhere? Thanks.

[bazar01]

Originally Posted by jmarch

I have one last question, does the resistor need to be re-mounted on the same spot? Is it there for cooling purposes or to monitor the amount of heat? Can it be mounted elsewhere? Thanks.

If you can mount it in a very accessible place, and have time to rewire and mount it on a aluminum heat sink, why not? They can get very hot when the fan runs in slow speed. The original one lasts about 15-20 years so if I have to replace it, I will just put it in the same spot and not worry about it.
Or I may even remove it so the fan runs only in high speed. I live in hot Georgia.
The resistor just provides electrical resistance to drop the voltage and reduce the fan speed when the control unit activates the slow speed section of the relay (85c and 86c)

[92964cab]

Originally Posted by jmarch

I have one last question, does the resistor need to be re-mounted on the same spot? Is it there for cooling purposes or to monitor the amount of heat? Can it be mounted elsewhere? Thanks.

yes, it can be mounted elsewhere
It's original location isn't exactly in a high air flow spot anyhow

Give me a call...
Mark D.

[cgfen]

for more than you'll ever really want to know about this..................... take a look @ Robin Sun's P-car.com site in the DIY section

964/993 Oil Cooler Fan Operation & Troubleshooting

Craig

[911nut]

Both of the resistors were shot on my car. Symptoms were the oil cooler fan not running at all and the condenser fan cycling on and off on the high speed setting when the a/c was engaged.
Replacing the resistors was a time-consuming job but required no special tools or knowledge. The oil cooler resistor was relatively easy to access but the condensor fan was a different matter.
The socket head screw that holds the condensor resistor was at a funny angle that made turning it with a key virtually impossible. I ended up smashing out the resistor and was finally able to turn the bolt out of the shroud.
While I was replacing the condenser resistor I was able to clean the trash that had accumulated in front of the condenser and renew the condenser-to-bumper foam seal that had perished.