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GQ A/C fan not coming on

Posted: Mon Sep 04, 2006 11:23 am
by Jimbo
Ok ppl my A/C thermo fan is not coming on with the air con. I pulled the grill off and checked to see if the fan was getting power and its NOT!!! GRRRRR

I ahve checked the pressure switch on the reciever dryer and that does not seem to be it. (i unplugged it and briged the wires and the air con came on but no fan)

What other senders or switches can i check????

Do you think the water temp sender (not gauge) may be faulty?

Any help would be great!!!

Cheers

Jimmy

Posted: Mon Sep 04, 2006 11:31 am
by chimpboy
I thought it just came on when the air con was switched on, and simply picks up power from the terminal on the compressor... ie wire from the compressor to a relay, then a wire from the relay to the fan.

In other words, no temperature sensing at all.

But I think these vary quite a lot between GQs...

Posted: Mon Sep 04, 2006 11:45 am
by Jimbo
Not sure i will have a look. Might be caked in mud

air con fan

Posted: Mon Sep 04, 2006 12:18 pm
by MUDDY MONTY
hi mine only turns on when air con is running ;)

Posted: Mon Sep 04, 2006 12:59 pm
by MKPatrolGuy
Check the relays under the black plate between the battery and the front guard. One of them is for the A/C fan.

Found this out because I have the opposite problem of the fan staying on (Even with the ignition off). By tapping that plate it knocks my sticky relay loose and stops the fan.

Posted: Mon Sep 04, 2006 1:00 pm
by Jimbo
ok will do

Posted: Mon Sep 04, 2006 4:46 pm
by RN
MKPatrolGuy wrote:Check the relays under the black plate between the battery and the front guard. One of them is for the A/C fan.

Found this out because I have the opposite problem of the fan staying on (Even with the ignition off). By tapping that plate it knocks my sticky relay loose and stops the fan.
Me too..pulled wire to the fan...

Posted: Mon Sep 04, 2006 6:12 pm
by NutterĀ®
Strangly my 92' GQ doesnt have one of these, yet every other one i have worked on even earlier ones have them.

Posted: Mon Sep 04, 2006 6:17 pm
by GQSWB42td
my 93 GQ is the same no fan but i have put one in.

Posted: Mon Sep 04, 2006 6:17 pm
by GQSWB42td
my 93 GQ is the same no fan but i have put one in.

Posted: Mon Sep 04, 2006 6:30 pm
by chimpboy
I understand that air con on the GQs is very variable, it really depends on who added it etc... so there are different compressors and other gear, and I guess that extends to there being different decisions about whether to add an auxiliary fan or not.

Posted: Mon Sep 04, 2006 9:53 pm
by awill4x4
Jimbo, if it's an efi GQ then it could be that it's triggered by the temp senders in the radiator. There are 2 senders on the cool side of the radiator (drivers side) one at the top of tank and one in the radiator outlet tube and I'm pretty sure these are used to trigger the AC fan.
Regards Andrew.

Posted: Tue Sep 05, 2006 9:05 am
by Jimbo
ok i check the fuses and relays and they are all fine. The A/C would not turn on with any of these pulled out.

Yes mine is an EFI. I have seen 2 senders where the top rad hose meets the engine. 1 of these is for the temp gauge and the other i think is temp sender fro computer. In my vp commodore i had a problem where the fan would not come on and it was this sensor but it used to come on woth a/c. Can u test this sensor easily with a multimetre? I might price one at nissan and change it anyway. I cant see it being too much.

Thanks and keep the ideas coming in.

Jimmy

thermo fan

Posted: Wed Sep 06, 2006 9:35 pm
by mgundle
i may be wrong but the thermo fan you are talking about may be activated when the high side a/c head pressure reachs a critcal level lets say 300psi so in doin so the pressure switch activates the relay activating the thermo fan i can remeber but thats how most older a/c thermo setups work, because if it were constantly running the a/c pressures wouldnt be effiecent for the a.c to work
not sure been a while since i have worked on one
my two cents.