liberty cooling fans ??

Chris_Rogers · Post by **Chris_Rogers** » Sat Nov 03, 2007 9:42 pm

how do these things work?

there are 4 relays, 2 for main fan 2 for sub fan. now my thinking (and reading of diagrams) is that the sub fans come in first when the A/C is on and the main fans come in when the car is at temp.

my dilemma is this: I have a BMW 16" fan and a Benz W203 fan - 16" item is for the main fan duties and the smaller benz item is for A/C.

the BMW one is 'joggable' by switching in a resistor (call it sub fan 1.)
and the main fan is direct into that same unit.(main fan 1)

If my thinking is correct I should be able to do the same with the smaller one - IE 'jog' it and switch it full speed.

the other thing is the A/C - I have the AC Request(brn/yel At ECU) wire set off the Compressor output of the cliamte control module. the car Idles up when you push the button for A/C but I do not know what the output does. looking at it I'm thinking its positive (it drives the compressor relay which in turn firet he A/C compressor.) again am I correct?

Am I right and can someone tell me how the hell these things (fans + A/C ) are meant to operate! (this is sending me slowly nuts!)

ta!

jzk25 · Post by **jzk25** » Sun Nov 04, 2007 2:15 pm

The A/C fans in liberty's are dual brush, one brush set is for A/C operation and the other is engine cooling. The ecu switches the fan relays from fan 1 and 2 outputs(grounds). On gen 1 and 2 the A/C system is wired so both fans come on if A/C is fitted but only fan 2 will be switched for engine cooling at ~100degrees. There are heaps of variations according to year model and engine type so it is hard to explain. I think you will find on a Gen2 TT that when A/C is requested that both fan 1 and 2 outputs are switched but only fan 2 is switched for engine cooling until 110degrees when the AC is switched off for safety reasons.

The A/C request is a 12v input, A/C comp clutch relay coil is then grounded by the A/C relay wire. Both wires go through other A/C switching though(A/C request through the pressure switch and A/C relay through the thermstat control).

Hope this makes some sort of sense, it's hard to explain clearly in text.
I normally bridge the fan 1 and 2 wires when fitting an EJ into a foreign vehicle and let the comp clutch switch the A/C fan relays.

Chris_Rogers · Post by **Chris_Rogers** » Sun Nov 04, 2007 10:35 pm

nope that made sense. in my case I wish to retain the OE operation of it. the A/C side of things I sussed.

when I put a A/C request into the ECU it fired the relays (one outside and one inside.) and the OE fans (that I'm using for testing in front of the car.) worked.

where does the cooling fan come in (100 deg C)?

I have the A/C side of it working. one other question - when I make an A/C request should the compressor kick in as well? (assuming I have the pressure switch and thermal switch bypassed)

also where is the evaporator switch? I *think* I left it in the cut leftovers and tossed it. thats the only bit I'm missing on the Legacy side of it.

jzk25 · Post by **jzk25** » Mon Nov 05, 2007 9:09 pm

Yes it is around 100degrees, earlier models were 95. If you have the fans wired so the A/C requset operates them than they will work with engine temp as well. You can test them by connecting the green and black plugs and switching the ignition on. The fans will switch on and off repeatedly.

When you give an A/C request the ecu will switch the fans on, up the idle a little and then operate the compressor clutch relay. The relay output from the ecu is sometimes call AC Cut Relay Control.

The evaporator thermo switch is a solid state thing on climate A/C, it is a block that screws into the lower half of the Evap box. The fan speed resistor is above it(also solid state).
Unless you are talking about the hi/lo pressure switch which is in the drier behind the pass. headlight.

Chris_Rogers · Post by **Chris_Rogers** » Mon Nov 05, 2007 10:33 pm

ok that makes sense. by rights making a AC request should drop a -ve on the comp clutch relay. if this is the case how soon should it happen? fans take 1-2 secs to kick in after a request and I'm assuming that the comp should follow (assuming safety is bypassed - lines are not in place.)

other than that the system works as described. both fans come on low speed when requested to via A/C. unable to check the engine temp side of things because I cannot get those fans in place. by wiring it should work.

I have the pressure switch still I reused 75% of the A/C system and mae new lines to suit the evap thermo got tossed the box with the a/c box.

I'm hoping adam still has his and he's not going to use it.
do you have a spare??

jzk25 · Post by **jzk25** » Tue Nov 06, 2007 8:23 pm

I don't have any Climate parts but they are all the same as Aussie gen 2's with climate so are available.

Chris_Rogers · Post by **Chris_Rogers** » Tue Nov 06, 2007 9:07 pm

ta. what spec am I looking for in the local ones?

also can I grab your P# pls. wnat to ask a few questions if possible