Air conditioning FIX
 

My A/C would only work on speed 1 and sometimes 2. I followed these instructions. R12 feels amazing.



Category Five Motorsports

Power-FC A/C MOD

This mod will enable your air conditioner to work when installing a Power FC in FD3s. This will also fix the problem of the a/c not working on one or more of the fan speeds.

The reason the a/c does not come on is because as the car ages, the ground signal going to the ECU’s (wire 1E) is receiving a fuzzy ground signal. Some cars have no problem with the signal, but some do; the last FD I worked on the a/c did not work on any speed. My mod will interrupt the signal going into the Power FC and redirect it through a simple Bosch relay. This will also let the Power FC still control the IAC and switch the a/c off at wide open throttle.

Locate wire 1E (Violet wire) - it is the third wire from the end on connector one. Cut the wire 2” from ECU. On the harness side you will hook 1E to (86). On terminal (85) on the relay will go to ignition +. Terminal (87) will go to 1E that was cut on the Power FC side. Terminal (30) will go straight to chassis ground. Now when your a/c is turned on, it will receive a nice healthy ground. If you have any questions contact me via email.

Freddie@catfivemotorsports.net

I just did this and it worked . I now have ac on all settings .

Sweet ;)!

have you ever encountered this . I'm trying to figure out if this is the power FC , or some other underlying issue

my fans work at all speeds . BUT my AC controls DO NOT WORK I cant switch hhere the air comeso ut , I cant turn on the AC nothing lights up when I press the AC button , or the recirc button , nothing works I thought it was a faulty control unit so I tried another one form a friend that was working and nothing did hte same thing . its as iff its not even recieving any power , the hazard lights work , and the cluster dimmer works . the fan speed works , but the temp , nor the directional flow controls work .

I'm wondering if this is caused by the Power FC . or if this is another underlying issue ..

I've checked all the fuses they seem to be good . I'm going to check the relay hope the relay has something to do with the controls .

Oh also I tested all the equipment manually using a test light nad they ALL OPerate
so its not that they are broken

Also my little fuse cover lost the label , I thought I read one fuse that said hazard /ac in whats left of the paper . But Now I'm doubtful . as I'm reading the FSM , Wiring diagram , Z68 , it says that the rear Wiper fuse is what feeds power to the AC controls ? is this correct ?

I got it figured out I just spammed this thread for nothing sorry!

What/which bosch relay and any pics?

Those relays are all the same.

"On terminal (85) on the relay will go to ignition +." Is there a certain location or color I'm looking for? Just want to confirm and clarify. Thanks. Would be nice to have all 4 AC settings, than just setting 1, lol. Thanks again.

I use one of those Greddy turbo timer harnesses that have a few wires hanging out. One is switched ignition that I use for my water injection, the other is Hot and I used that for the relay.

I've got these issues with my 93. However, I do not have Power FC. Would this fix still be implemented? If so, does anyone know a thread with more instructions or pic walk through?

Here it is.

pictures? :D

This is not kinder garden or grade school.
That is what the FSM is for, to find where things are and how they work to some degree.

You either have the knack or pay someone to do it.

As mentioned in my original question - these instructions all reference having a Power FC mod.. which I do not have. Hence why I am looking for more details because these instructions are very specific to the wiring of the PFC. While I have the same symptoms - these might not provide the same resolution if they are specific to PFC issues... so no, I am not asking to be taught like a grade schooler, simply asking people broader questions to clarify the original op's posting. Thanks

Applies to the stock ecu the same as the PFC. The wiring change will relate to any ecu that uses the AC switch and fan speed in the same way as stock, and controls the idle speed.
Only would be different if the AC was greatly modified over stock.

The AC could be wired to not even connect to the ECU as the ecu connection is only for ISC control.

If you understand basic DC circuits and read the manuals for the AC, then you would understand.
If you do not know electronics or basic wiring, do not try it alone.

I just follow the op's instructions and it worked perfect for me. My pin 1E was black with a yellow stripe on my 93 touring, but it worked just the same. I had a/c in fan speed 1 only before the mod. Now after the addition of the relay all 4 work great. Very good stuff!

I performed this mod and the AC is working on all 4 settings. Still running into some issues that I don't think are necessarily tied to PFC. I will be posting further about this once I get them well documented.

I am considering doing this mod but after thinking about the logic of the relay, I'm wondering something: Why not just splice the 1E wire directly to a clean chassis ground rather than have it switch to the chassis ground only when the ignition switch is turned on?

Maybe I'm missing something in the logic? With this relay mod, when the ignition switch is off, wire 1E coming out of PFC is disconnected from the ground, and when the ignition is turned on, wire 1E is then connected to the chassis ground. Without the relay mod, wire 1E is always connected to a chassis ground (albeit a fuzzy one).

So wouldn't the more logical solution be to simply splice or cut and connect wire 1E coming out of the PFC directly to a clean chassis ground?

Yes you are missing something, not understanding how the circuit works!
Go back and study Freddy's mod, and also look at the manuals FSM Section F and the Wiring manual for the AC.

Your way is fine if you want your AC running 100% of the time.

HAHAHAHA!

Ah - I see what you're saying. I was thinking that the 1E on the harness side was going straight to chassis ground, but it actually is only switched to ground when a signal is activated to turn on the AC compressor through a myriad of circuits.

Thanks for the clarification!

Fan Speed Fix
 

I concur with previous posts, just follow the directions as posted. Took about 1 1/2hrs.

Thanks much Freddie.

Gents,

I tried to reach Freddy, but found that his email no longer works. I'm hoping that someone can drop some knowledge on me ? My question is as follows:

I plugged in a bosch solenoid as per the instructions, and the solenoid clicks when I hit the AC button, the AC light illuminates, and the cooling fans come on (I have them set way low on the PFC when AC is active).

I'm still not getting the compressor to engage however and I've tried troubleshooting but I'm stuck: I have the pressure sensor jumpered (system isn't charged right now) and i can get compressor engagement if I jumper the AC clutch solenoid (see attached wiring diagram). So, my thought process is that the AC compressor clutch solenoid isn't getting a ground from the PFC.

It appears that the control wire for the solenoid terminates as an input at 37 into the PFC (which is pin 1L). This is where my understanding breaks down - how does the PFC control the solenoid if pin 1L is an input?

Thanks in advance for anything that you all can offer

Aaron

How did you get on with this? I am having a similar issue myself.

I live in Australia and have a s8 (2001) fd with a power-fc. The wiring diagram/pinout is a little different, but AFAIK, the wire colours have remained the same. I tested the whole system extensively as I thought my compressor clutch was the issue. Turns out the power FC is not activating the A/C relay. I traced the wire and tested it for continuity. Everything seems fine. I am tempted to just bridge the relay in the short term as it is summer here. But I would like to know if there is a more permanent solution.

I tried the relay mod on the violet wire, but this has not helped. The fans come out and it seems as if the idle is being compensated, so surely it is not too much of a stretch to get this relay to activate.

I guess I would be prepared to either wire in another relay or rewire the current relay so it activates off the A/C switch in cabin. I can always turn it off easily if driving in a spirited fashion.

Still stuck! Getting ready to take the car out of winter storage, and I'm eager to get this sorted out. Maybe it's something to do with the evaporator sensor to prevent icing?

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.

Blower fan levels
 

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

https://cimg8.ibsrv.net/gimg/www.rx7...eb4aa58b8.jpeg
Ac off
https://cimg7.ibsrv.net/gimg/www.rx7...0ca7819b0.jpeg
Ac on

This is the later ECU pin out, presume it’s 4V ac switch that needs the relay fitting to it
https://cimg8.ibsrv.net/gimg/www.rx7...8e46d0423.jpeg

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!