got mine working - I cut the control wire from the pfc that draws the ac compressor solenoid control circuit to ground and wired it into the Bosch solenoid-to-ground fix that was suggested earlier in this thread. The pfc wasn't pulling a strong ground on 35 in the manual (pin 1L) even with Freddie's solenoid fix. I could have used a second solenoid which would retain the high load compressor cutout which this doesn't. This does retain the pressure and thermo switch control.

 

I am still having issues as I have a 2001 model and the pin layout is different to the 93-94 spec cars which is the only wiring diagrams I can find.

I did the mod as per the instructions, Using the only violet wire in the harness, but the relay isn't being activated.

I figured out the wire that runs to the relay Yellow/Black stripe, but I am not 100% sure that the violet wire is the right one, as it is on a different connector.

If I can activate the relay then we are all good. I am considering just putting in a manual switch. Really frustrating especially when it is summer here in Australia.

 

I tried to contact Freddie too...email must have changed. I had a couple of questions.... the Violet wire, on the 93 controls the AC thermo switch, the Y/B (yellow/black) is the AC ground into the ECU, just wondering why he used the thermo ground and not the AC gound. I don't know how the relay improves the ground, it simply reconnects the wire when the ignition is turned on, can anyone clarify this?

 

TO anyone that's done this mod....where did you pick up the ignition+....is there any ignition+ going into the ECU....or somewhere close to the ECU.

 

I did Freddies mod, picked up the ignition+ from the 1B pin on the same ECU harness (fuel injector relay 12v)...the mod worked. Once the car is warmed up the FC isn't raising the RPM with the AC on so the car wants to almost stall (500 RPM). I set the FC AC idle at 1000rpm but it hasn't changed it yet.....may have to drive around for a bit.

 

How you doing guys.. I have a problem on my fd3s. I turn on the blower on 1st and 2nd level and it turn on the radiator fans.. and the 3rd and 4th work fine.. Is anyone knows how to I fix it.??

 

This can be a useful mod, but I just wanted to add that I fixed this problem by replacing the fan speed switch with a new part. Before I did that, I had AC compressor clutch function with fan speeds 1 and 2 only. With the new switch, it is working on all 4 speeds. I also used a little dielectric grease on the switch plug terminals - something I am doing on every electrical connection I touch in my FD now.

Nothing wrong with doing the relay mod, but I wanted to try a fix that did not involve changing the original wiring. For now, it is working. Fan switches are still available AFAIK- about $75 so much more expensive than a relay and some wire I agree, but this seems to resolve the problem without any wiring mods.

 

Bump from the dead just to say thank you to this forum and it’s incredible members!

Fixed my a/c in 15 minutes after searching the forum, thanks to everyones diligence in sharing their knowledge.

Cant even begin to count the number of things I’ve fixed/learned in just a couple minutes of searching over the years here.

Thanks to all!

 

I've confirmed that a new Fan Switch (now $90 from Ray Crowe) fixed my problem. Originally my fan 3 didn't work, then 2 and 4 a year later. After receiving the switch (took a few minutes to install) now all 4 fan speeds work with the AC! I didn't want to mess with the factory wiring until that option is no longer available.

 

The fan switch can be fixed by taking it apart and cleaning the contacts with fine sandpaper or a Scotch Brite pad....I did it and it works fine...saved the $90.

 

I did that to my old switch, unfortunately it only restored my fan 2 and 4 intermittently, so I went with the next option, a new switch.

 

Sorry to revive an old thread, but all of my searching is turning up nothing. I just installed a Power FC in my 93 touring, and now my a/c only works on setting 1. I took the switch apart and cleaned all of the contacts, and I wired in the relay exactly as shown in Freddie’s how-to, but still no change except that the light in the a/c button on the dash doesn’t flicker anymore. The switches aren’t available new anymore, so that option is out. Is there anything else I can do?

I did have a thought, but I wanted input before I tried it. If the reason the Power FC has trouble is because of a staticky ground signal on the switch, can I just run a new ground from the black wire on the back of the switch, to a clean point on the chassis?

 

I don't see how that could harm anything...worth a try. My problem was compounded by a bad Thermo switch, the one that sends a tube into the evaporator to control icing. I looked all over for a new switch....discontinued. You'd think with all the Denso air con on other cars there'd be a substitute part? I wound up just disconnecting the switch, the AC works on all fan settings now. The only problem would be in colder climates the evaporator may ice up.

 

Where is that switch located? I’ll go ahead and test mine to make sure it’s still good. Thank you for the response.

 

For my RHD car, its on the top left of the evaporator. You can remove the plug to it and test without removing it, just drop the top part of the glove box. I assume the LHD car is the same, just reverse the sides.

 

I wired the black wire on the harness side of the plug (not the black wire coming out of the switch!) straight to the steel dash support beam. I now have working a/c in 1, 2, and 4. It’s better than only having it in 1, so I’ll take it.

 

I want to add a note here:
Purchased a brand new fan switch last year, AC kicked on in all 4 speeds, worked great. Today, the compressor doesn't kick on in speed 3. I think the only true fix is the relay mod for the Power FC, not the fan switch.

 

I have a 99 FD I believe the issue is ECU related, basically I get a light on the ac button and I believe the relay is kicking in but I don’t think the clutch does on the AC pump. Can’t see any fluid moving in the peep hole (had the system pressure tested and regassed the other week the guy said it didn’t work at first then it kicked in so just presume it was because it was empty?) I checked the sensor check and when I hit the ac I get the exhaust temp and cat switches light up but not the ac?
Is this the earth issue mentioned here?
car has a decat btw
thanks in advance


Ac off

Ac on

 

This is the later ECU pin out, presume it’s 4V ac switch that needs the relay fitting to it

 

The Thermo sensor probe that's in the evaporator may be bad...if so the A/C will kick on for a moment, then turn off. Mine was bad, I jumped it and the A/C works fine. I've tried finding the sensor, it's discontinued, a Denso part. I tried cross referencing, you'd think with all the Denso A/C units out there, there would be something that would fit....no luck! The senor is supposed to stop icing of the evaporator....I live in Florida, so I don't think it'd be a problem to just leave it jumped.

 

The manual will tell you how to test thermosensor. I have a JDM 96 and JDM 92 evap w/ thermosensor, they are the same.

Greg, not sure if you have a JDM car, but I have a spare evap with thermosensor for one. Maybe the same sensor?

 

When I jump the relay I get the ac switch on and clutch engages, relay checked out ok so I will test the pressure and thermostatic switch’s for faults

 

See attached for service manual

 

so when you jumped the AC relay and the clutch pulled in you had ac again? I did that to mine but it still doesn’t blow cold even with the clutch engaged it was pressure tested and refilled the other week and I can see movement of gas in the peep hole on the dryer???

 

Thanks for the reply AE.... My FD is a 1993 USA east coast...The AC thermoswitch is in the Mana Design evaporator. The Mazda part # for the thermoswitch is FD01-61-J20. This part is discontinued, but with all the AC units out there it's hard to believe there isn't another Thermoswitch that would fit. My AC is working well with the Thermoswitch jumped. To replace the thermoswitch involves removing the evaporator box and disassembling it, because of the long thermoswitch probe tube....it's a pain!