1G AC switch not turning fans on

ErikTande · Aug 8, 2015

When I turn the ignition on and turn the AC switch on (light goes orange and green like it should) the fans should come on as well right? Even if the car isn't running?

I ask because mine don't come on with the switch. What would cause them not to come on?

Dhan · Aug 8, 2015

I had a similar situation on my FWD turbo. I started by seeing if I had voltage at the fan itself using a multimeter and traced back from there. Double-check grounds also.

With my car I had fitment issues with the J-pipe and the stock radiator fan. I ditched the radiator fan and left the A/C fan in and just hit the snowflake button whenever I'm at a stop light or whatever.
Anyway, one day the fan didn't come on. Traced the problem to faulty wiring in the fusebox that's in the corner of the engine bay nearest the driver. Cleaned and soldered the bad wiring and harnesses and it worked again.

Check the easy stuff first.

And yes, the fan should come on when the car is off but the key is in the "acc." position.

ErikTande · Aug 9, 2015

Yeah, they kick on at stoplights, etc, but not when the AC is is pressed. I'll check the drivers side fuse box. Thanks!

DSM1G90 · Aug 9, 2015

Also, there are relays under the black box by the passenger strut that controls these fans. When you flip the fan switch, it closes a relay to activate both fans since both comes on when AC button is pressed in. One could be hanging up. You can swap these relays around to find the bad one.

ErikTande · Aug 9, 2015

DSM1G90 said:
Also, there are relays under the black box by the passenger strut that controls these fans. When you flip the fan switch, it closes a relay to activate both fans since both comes on when AC button is pressed in. One could be hanging up. You can swap these relays around to find the bad one.

Good, info, thanks. I tried swapping the fog light and fan relay on the passenger side, no change. And I know the fog light relay was good, because the fight lights turned off when I unplugged it. So I know that part is good.

ErikTande · Aug 9, 2015

Dhan said:
I had a similar situation on my FWD turbo. I started by seeing if I had voltage at the fan itself using a multimeter and traced back from there. Double-check grounds also.

With my car I had fitment issues with the J-pipe and the stock radiator fan. I ditched the radiator fan and left the A/C fan in and just hit the snowflake button whenever I'm at a stop light or whatever.
Anyway, one day the fan didn't come on. Traced the problem to faulty wiring in the fusebox that's in the corner of the engine bay nearest the driver. Cleaned and soldered the bad wiring and harnesses and it worked again.

Check the easy stuff first.

And yes, the fan should come on when the car is off but the key is in the "acc." position.

I checked those harnesses up by the drivers side, they all look good. I unplugged and replugged, no change. This VFAQ shows if I jump pins 1 and 3 the fans should kick on, but they don't. (They used to, I tried this before on my car last year). http://www.vfaq.com/mods/wayback/1gcoolingfan.html

What should I check next?

Dhan · Aug 9, 2015

Yeah I would just check to see if the fan is even working. May have burnt out.

In the photo I posted, it shows the A/C fan harness. The upper left pin is 1, upper right pin is 2. Bottom left pin is 3 and bottom right pin is 4.

You jump pins 3 and 4 to test if the fan powers on. Pin 3 gets power, pin 4 gets the ground.

Also check the resistance of pins 1 and 2. I got about 1.3 ohms on the two A/C fans I have (and they both work). I don't have the FSM in front of me so I can't tell ya what the standard spec is.

91-GS · Aug 9, 2015

Did not see that here, but have you checked the switch itself? There is a chance that it got corroded on the inside (either a liquid splashed on it, or just from age) and that caused it to stop working.

JKart · Aug 10, 2015

It could be 3 things. 1 blown fuse, busted relay or worn out blower motor.

ErikTande · Aug 10, 2015

Dhan said:
Yeah I would just check to see if the fan is even working. May have burnt out.

In the photo I posted, it shows the A/C fan harness. The upper left pin is 1, upper right pin is 2. Bottom left pin is 3 and bottom right pin is 4.

You jump pins 3 and 4 to test if the fan powers on. Pin 3 gets power, pin 4 gets the ground.

Also check the resistance of pins 1 and 2. I got about 1.3 ohms on the two A/C fans I have (and they both work). I don't have the FSM in front of me so I can't tell ya what the standard spec is.

The fans themselves are definitely working. They turn on when the car is stopped and warm.

DSM1G90 · Aug 12, 2015

to your original question: Fans operate with the key on ACC, not in the off position since there is no delay relay in the circuit.

Also, the fan switch has to be on, even on first click with your AC button pressed in-either orange or green, to get both fans to come on.

I do this trick if I'm really stuck in stop and go traffic to pull air through the radiator to keep the coolant temp at a operating level...I have no AC which was removed, but the electrical part remains intact.

Good luck - DSM

Dhan · Aug 12, 2015

Well, if the fans are working and the A/C is blowing cold, it sounds like the system is working well enough. If it's just not coming on when the car's off and the key's in the ACC position, its gonna be hard to diagnose over the net. Would have to pull out the wiring diagram in the FSM then use a multimeter and 12V power source to test for the problem.

I would just keep poking around with the wiring and the switch.

1990TSIAWDTALON · Aug 12, 2015

Erik, make sure you have the fan switch in an "on" position. I keep mine on low and it should kick the fans on. Just pressing the button won't get them to turn on. Just fyi.

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