Andre The Giant

I have never seen or heard this fan come on, how can I test to see why ?
As per the PET diagram, can anyone explain which parts to test and how ?
I need to make sure that if it has to come on, it will !

928NOOBIE

It's a pusher fan designed to work via a pressure switch for the AC system. It can also be triggered to run at half speed via after-engine cooling.

To test it you can close the switch manually by jumpering the intake temperature switch..that should switch the fan on half speed.

For AC once the temp/pressure of the system hit a threshold it comes on.

Engine temp can make it come on also.

Easiest way I can see to test it running is after engine cooling circuit, assuming the fuse is good....

davek9

Yep, there is a two prong temp sensor in the front on one of the Intake tubes, you should have 12v's there with the engine/switch off.
If the 12v is there jump the wires and the Fan should run as stated above, you could also try to directly power it at the white connector at the fan w/ 12v battery (i'd suggest a fuse in-line) for safety.

Dave K

Majestic Moose

I know it is triggered by the AC temp sensor on the drier (part 28) disconnect and jumper the two wires out of the sensor and that will switch on the fan (with ignition on).

The Forgotten On

For 86 and back the system has two temperature sensors that cause the fan to run. One is screwed into the top of the receiver drier and has two short wires that lead to spade connectors.

The other sensor is screwed into the bottom right side of the radiator under a boot with two spade connectors. This is the one that senses the coolant temps. This sensor is mechanical and will eventually fail.

A new one is ~$10 and they come in different temperature ratings so you can choose when you want the auxiliary fan to come on.

Andre The Giant

Great thank you everyone for the great info. I will definitely test this temp sensor # 28 and then decide what my plan of attack will be. I will also apply 12 volts to the fan to make sure it runs normally. I will post my results once I get a chance.

davek9

Incorrect, there are THREE

The Intake over temp on manifold as I mentioned is the easiest to get to

And actually there could be a fourth if you count the "trailer towing" option wires over by the Jump Post
I don't recall the 85/86 having the Auto Trans over temp, I think that started in '87 I'd have to look

Dave

The Forgotten On

They didn't have an intake temp sensor prior to the LH cars, so I digress