AE_Racer

iTrader: (1)

Hey guys,

Finally appears I have my a/c going in my car after lots of trials and money lol. My car is a JDM 92 with a power FC.

The compressor clutch is kicking on, and the a/c cools great in cruising. However, its not turning the engine cooling fans on low as it appears it should. The fans turn on fine at their set coolant temp through the power fc (Fan1 a/c, 89C, Fan1 no a/c 90C, Fan2 92C).

Should the fan1 a/c setting be lowered, or should the fans automatically go to low when I request a/c? Everything im reading makes it seem to be the latter but just want to be sure.

Ive spent the past couple hours researching but most of the info I find is about the power fc and the cabin blower fan. Just want to make sure there’s not something simple or stupid im overlooking before I go digging into the relays and wiring. Thanks a lot.

DaleClark

iTrader: (55)

The PFC shows 3 fan speed settings but that only applies to the later 96+ JDM cars. The ECU in the 92-95 cars only has control of 1 fan speed input. I would just set those 3 values to be the same.

You'll have to go through the shop manual and troubleshoot why it's not coming on. There's no computer control, it should just be if the AC button is on in the dash the fans kick up 1 fan speed.

Dale

AE_Racer

iTrader: (1)

Great info. Will update when I figure out the issue. Thanks as always.

IRPerformance

iTrader: (41)

Is the ac light coming on in the sensor/switch check menu when turning on the ac? If not the pfc might not be seeing the ground signal from the climate control panel. Wiring in a relay usually fixes it. The other thing I had a recent problem with is the climate control logicon where it wasn't engaging the ac even though the orange light was coming on. Switched out the control panel and it resolved it.

AE_Racer

iTrader: (1)

I will check that. The light comes on the hvac a/c button and the a/c works great, just no fans running so once you stop moving it blows more warm.

AE_Racer

iTrader: (1)

A/C does illuminate on commander when requested.

DaleClark

iTrader: (55)

It sounds like the AC is all doing what it should but the fan part of that system is what's not happening. I would start with the relay.

There are 4 fan relays bolted to the passenger side shock tower. There is going to be one that has a larger 6-pin connector, that should be fan relay #1 which is the AC relay. It's in section B-2 of the wiring diagram. I would check that connector to that relay and maybe bypass the relay with a wire to see if the fan will come on. You can also see if the relay input gets 12v when you turn the AC on there.

Dale

AE_Racer

iTrader: (1)

Thanks Dale, will check that out tomorrow.

AE_Racer

iTrader: (1)

I can jump the wiring at the relay plug and turn the fans on. Im seeing +12v at the large blue wire, and the smaller black and yellow stripe wire, regardless of a/c on or not.

the other large wire, yellow, I jumped to turn the fans on. No power at pinkish colored one.

found the b-2 diagram but kinda lost when looking at those.

AE_Racer

iTrader: (1)

Think I figured it out, the pink wire should be ground? this is done through the hvac brain?

edit: yep. Grounded pink and turned fans on with relay in place. Digging deeper lol

AE_Racer

iTrader: (1)

Best I can tell this is something to do with the control unit or a/c switch not grounding the V/P wire? Have another i'll swap in tomorrow and see unless someone here thinks of something else.

AE_Racer

iTrader: (1)

Swapped hvac control panels this morning. Same result.

DaleClark

iTrader: (55)

Yep, grounding the wire going to the heater control in the diagram will kick the relay on. Next step is to figure out where that wire goes and why it's not grounding.

Section G in the wiring diagram.

Dale

AE_Racer

iTrader: (1)

It goes into the hvac control unit which ive just tested along with the thermosensor and the wiring in between as outlined in the work shop manual. So gotta be somewhere between the control unit and that relay.

AE_Racer

iTrader: (1)

This is what im trying to decipher so far. It looks similar to the US diagrams but then again not.

nmoffatt

iTrader: (15)

Bumping this thread as I am having a similar issue and am completely stuck. Been studying the wiring diagram and countless posts over the last couple of days and this post seems to be the closest.

Problem: Relay #1 that controls the cooling fans when the AC is turned on no longer de-energizes when the ignition is turned off (Accessories ON or key removed). So in my case the cooling fans never turn off (Opposite what the OP poster reported) and will keep running until the battery is dead. When the ignition is turned on the relay de-energizes (fans turn off) and the AC works normally. The relay will re-energize once I click the AC button and turn the fan on any speed and de-energize once I turn the AC off.

How I got here: I've been running the PFC for a few weeks now and decided to do the PFC relay fix to get the AC going again. That part worked and the AC is fine but I noticed right away that the fans would come on the moment I reconnected the negative terminal on the battery. Nothing else was touched which is weird.

What I have tried so far:

1) Came across the Mazda fan recall in my searching. Thought maybe this might have something to do with it so I removed both harnesses. Unfortunately this had no effect.
2) Tested all 4 relays and they all work fine. This is where I found that it was relay #1 that was causing the issue.
3) Rolled back the PFC AC fix and reconnected 1E back the way it was and retested. No help there either.
4) Unplugged the PFC altogether and re-tested. Same behavior. Fan control for the AC should not be affected whether the ECU is plugged in from what I am reading. Like I mentioned it works as expected when the key is turned to ignition.
5) Put back the stock ECU and retested. Same result.
6) Checked the thermoswitch on the AC unit and tested as per the FSM and it passed.
7) Set up a multi meter on the ground going into the relay coil. This is supposed to be a switched ground once the AC button is pushed to energize the relay and turn the fans on. (positive side always has power from the battery so the ground controls the fans). I can see it is always grounded UNLESS I turn the key to ignition. Then the ground switched off.

So what I am banging my head against the wall to figure out is what controls this ground signal to the relay? At first I thought it had something to do with what I changed with the AC fix but have recently come to accept that there was another issue that came to the surface that I stumbled across or disturbed. Any advice would be appreciated.

Thanks!