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How to get the A/C fan to come on when pressing the switch?

Posted: Thu Jan 29, 2009 5:43 pm
by enthuzed
Given Melbourne's heatwave, and knowing that it's not a good thing to run the air conditioning without the fan running, does anyone know how to set up the fan(s) to come on immediately when activating A/C in the car?

Currently my A/C fan only comes on with the radiator fan, which is better than not at all, but the ECU (?) decides when to run the radiator fan.

I know not to run the A/C when stationary for very long because the heat doesnt dissipate and the A/C system pressure can go through the roof.

Haven't had a chance to look at the wiring diagram, and its too bloody hot right now to concentrate on it anyhow...but theres probably a simple solution.

Thanks...

Posted: Thu Jan 29, 2009 5:54 pm
by FST4RD
SW20 MR2's were simple.... if you unplugged the temp sensor in the engine bay as soon as you turned the car on it would start..... great for drag days....

Posted: Thu Jan 29, 2009 5:59 pm
by thrash
melbourne.. too hot??? rofl

what's the temp down there?

my ac fan is on whenever the car is on.....

Posted: Thu Jan 29, 2009 6:34 pm
by Adriano
You cant damage the a/c system with too much pressure, as there is two pressure switches that cut the a/c off.

Posted: Thu Jan 29, 2009 7:27 pm
by enthuzed
Interesting you say that Adriano, the A/C guys told me I should get the fan to work as soon as the A/C button is pushed, something about blowing seals from too much pressure. This was after they regassed it, and they deliberately left a wire off that goes to the compressor for that reason.

I dont know enough about it so I've asked the question here. Can you elaborate?

Also mate, welcome to the forums! People here genuinely try to help one another. Give each other a bit of curry for fun too, but mostly try to help...

Posted: Thu Jan 29, 2009 7:29 pm
by enthuzed
thrash wrote:melbourne.. too hot??? rofl

what's the temp down there?

my ac fan is on whenever the car is on.....
You had your heat wave last week, and now you shits have passed it southwards. You're just too kind! :wink:

Posted: Thu Jan 29, 2009 9:28 pm
by JPC
The main (larger) fan turns on when the temp (as detected by the temp sensor switch at the bottom of the radiator) reaches a certain value. The ECU doesn't have a part in this - the radiator sensor is nothing more than a temp-activated switch.

As standard (on JAs at least), the secondary (smaller) fan should come on when the A/C comes on, regardless of whether the main fan is on or not.

Posted: Fri Jan 30, 2009 8:29 am
by panda
The climate here in Mount Gambier is typically "Tasmanian", normally cool & wet. It has been 44 degrees everyday here for the last 3 days, but today is cooler, only 41 degrees. :) Don't need air cond in my car as I'm not even going outside ! :P

Posted: Fri Jan 30, 2009 9:02 pm
by redzone
JPC wrote:The main (larger) fan turns on when the temp (as detected by the temp sensor switch at the bottom of the radiator) reaches a certain value. The ECU doesn't have a part in this - the radiator sensor is nothing more than a temp-activated switch.

As standard (on JAs at least), the secondary (smaller) fan should come on when the A/C comes on, regardless of whether the main fan is on or not.
exactly what he said :)

Posted: Sat Jan 31, 2009 8:58 am
by enthuzed
Apparently it wasn't coming on properly but the radiator and all sundry items have been disconnected and reconnected, so it might be working properly now...I'll check what it's doing.

So just to clarify, proper operation is, push A/C button in, small fan comes on immediately. Right?

One of my other cars didn't do that so that's why I'm asking.

Posted: Sun Feb 01, 2009 1:04 am
by redzone
when the a/c cycles, the fan comes on..

Posted: Mon Feb 02, 2009 11:39 pm
by JPC
Don't forget, pressing the A/C switch does nothing until you turn on the interior air vent fan.