Andre The Giant

Since I got the car in 2013 I have yet to notice the AC fan ever turn on, so I would like to know what test can I do either voltmeter or something else to verify the operation of this fan.

I have included a picture of the system. I also saw as per WSM that there is a low pressure switch and a temp sensor attached to the condenser, can I also test those items and how. Please keep in mind I am technical but only in computers, not mechanical.

WallyP

On the '85, the Aux Fan is controlled by:
- Coolant temp sensor in left bottom of the forward face of the radiator.
- Air Temp Sensor in the top of the intake manifold. (Only for slower run-on after hot shut-down, with ignition off.)
- ATF Temp Sensor in automatic transmission.
- Refrigerant Temp Sensor on stem of Receiver/Dryer. Not very effective. I think that installing a relay that controls the compressor clutch and the aux fan is a better idea. Takes the load off the undersized relay in the HVAC head unit, and ensures that the fan runs whenever the compressor is on. You also need a diode to prevent a coolant, intake manifold, or ATF event from operating the compressor clutch.

The only test of the refrigerant sensor would be to check continuity thru the temp sensor when the refrigerant is hot.

bureau13

A super easy test to see if the fan itself works is to unplug the wires from the temp sensor on the radiator (front, driver's side near the bottom) and bridge them together.

My sensor has a broken connector, so I have for now just permanently bypassed that sensor...the fan always runs. Next time I need to drain the radiator for some other reason, I'll replace the sensor.

PorKen

'85-'86 ONLY if equipped with factory towing package.

Temp switch is installed in the header of the external auto trans cooler.



('87-up autos have a sensor in the output line of the cooling circuit.)

MainePorsche

Andre,
You could try troubleshooting the electrics from the controller unit under the passenger seat. Will tell you if current is being sensed and sent to the fan appropriately. If controller/amplifier checks out well then only need to test for voltage at the connector to the fan to see if it is a wiring fault to the fan.

Add: the delineation of the pins are on the cover of the controller unit.

bureau13

'85 has the belt-driven primary fan and the single electric aux fan...none of that new-fangled-under-the-passenger-seat ****e

bureau13

The forum is censoring ****e now? Lol when did that ****e start?

MainePorsche

So no controller for coolant temp, torque converter ATF temp, air intake temp, and AC refrigerant pressure/temp ??

Andre The Giant

Thank you Jeff I will check that, when I return from frenzy.

Andre The Giant

I don't think I have the towing package ! But I will check for that connector. Thank you.

Andre The Giant

I am glad I don't have that extra ****e to check . LOL

MainePorsche

My bad Andre.
When I copied those pages from Ligeti.com, I thought it was for a pre S4.

Andre The Giant

No problem, you were trying to help and that is all I asked for.

hwyengr

It's also possible that your belt-driven fan is in good shape, and living up North, nothing ever gets hot enough to trigger the fan. Mine only seems to kick on during really hot days when I'm stuck in traffic, or on really-really hot days after I shut it off.

Andre The Giant

Thank you Jeremy. That is entirely possible, but that is why I would like to test it's functionality now before it's too late and it heats up in long traffic on a hot day.