Power FC THE power FC A/C fix!!!
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Mr rx-7 tt I think your issues maybe a poor grounding issue for the relay. Since your PFC works fine in another car but not yours. And also the fact that you used a different PFC on your car with the same result. This indicates that the problems now lies with the PFC not playing well with your AC in your car. So start trying all the easy fixes first then work your through it. I am in the process of doing the quick fixes now
Quite simply the PFC operates on differrent voltages (or tolerances) for the A/C control wire than the stock ECU. That is why it does not operate the A/C correctly.....
Knowing that... what other sensors and switches does it read inconsistanly.....or not at all?
Knowing that... what other sensors and switches does it read inconsistanly.....or not at all?
Originally Posted by HYDOUKEN
Mr rx-7 tt I think your issues maybe a poor grounding issue for the relay. Since your PFC works fine in another car but not yours. And also the fact that you used a different PFC on your car with the same result. This indicates that the problems now lies with the PFC not playing well with your AC in your car. So start trying all the easy fixes first then work your through it. I am in the process of doing the quick fixes now
Originally Posted by HYDOUKEN
Do a quick search and you will find sooo many post about this. I personally think your situation is a ground issue.....not a low freon or anything like that.
Thread Starter
Joined: Apr 2002
Posts: 2,194
Likes: 2
From: Dayton, OH
Update
After seeing other people try this fix and have no positive results, I wondered if my car was on the edge of tolerances and the diode was just enough to keep it on the green. It looks like that was the case. Recently, my a/c stopped working on fan speed 4.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
Originally Posted by poss
After seeing other people try this fix and have no positive results, I wondered if my car was on the edge of tolerances and the diode was just enough to keep it on the green. It looks like that was the case. Recently, my a/c stopped working on fan speed 4.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
Originally Posted by poss
After seeing other people try this fix and have no positive results, I wondered if my car was on the edge of tolerances and the diode was just enough to keep it on the green. It looks like that was the case. Recently, my a/c stopped working on fan speed 4.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
Thread Starter
Joined: Apr 2002
Posts: 2,194
Likes: 2
From: Dayton, OH
Yes, of the wires coming directly out of the fans switch, the red one is the ground. You'll notice it changes to black at the first connection. I used 14 gauge wire. I probably should have gone with some 12, but that's what I had lying around and it works.
My air worked all weekend; so-far-so-good.
My air worked all weekend; so-far-so-good.
Thread Starter
Joined: Apr 2002
Posts: 2,194
Likes: 2
From: Dayton, OH
That's backwards from what the problem normally is. Do you have a commander for your PFC? Go to the sensor check menu (etc.->sw/sensor check I think) and see if the A/C indicator is on for fan speeds 1-3. If it isn't lit up, it's probably a grounding/voltage problem and see above "fixes."
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Originally Posted by poss
After seeing other people try this fix and have no positive results, I wondered if my car was on the edge of tolerances and the diode was just enough to keep it on the green. It looks like that was the case. Recently, my a/c stopped working on fan speed 4.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
So I went back to the old tried and true method cleaning the switch and adding a ground. Unfortunately, I don't have any pictures, but the switch cleaning is pretty self explanitory. Everything comes apart without any complexity and goes back the same way. After I cleaned the switch I tested it to no avail, however I did notice that the ground wire developed some heat in the short amount of time during testing. That fan motor must draw some current! Anyway, I spliced in a ground wire to the red wire coming out of the back very close to the switch itself. I then ran the ground wire to the dash support beam. There is a slot welded to the beam directly behind the a/c panel that I connected it to with a ring terminal and screw/nut. Mine had a thin layer of rust that I sanded off first to ensure a good connection. I put everything back together and woo hoo, I have air again.
Originally Posted by powermalex
OK
Here's the deal.
I installed the stock ECU with the M2 Stage 3 map upgrade just to make sure the AC does work. blows 38 degrees (Nice!)
Next installed the PFC A/C only works on SW1.
I grounded the purple wire on the ECU just like the switch does drove it and its back to 38 degrees. THis was a temp wire just to make sure it works.
Next I installed relay at switch location to ground the green wire when switch is on. The relay also gets its ground from the switch. Since the relay is not voltage sensitive a bad ground through the switch still energizes it. It needs 9 to 12 volts for the relay to work.
Now my AC works with the PFC just like the stock ECU. I beleive the real fix is to replace the switch. BTW I did order a new Switch that will be in next week for $75.00 which I will install. The relay should be the fix but I don't like to bastardize any of the electronics.
Also I beleive a grounding kit for the FD is needed. I found anywhere from 1 to 3 volts from ground to ground.
Here's the deal.
I installed the stock ECU with the M2 Stage 3 map upgrade just to make sure the AC does work. blows 38 degrees (Nice!)
Next installed the PFC A/C only works on SW1.
I grounded the purple wire on the ECU just like the switch does drove it and its back to 38 degrees. THis was a temp wire just to make sure it works.
Next I installed relay at switch location to ground the green wire when switch is on. The relay also gets its ground from the switch. Since the relay is not voltage sensitive a bad ground through the switch still energizes it. It needs 9 to 12 volts for the relay to work.
Now my AC works with the PFC just like the stock ECU. I beleive the real fix is to replace the switch. BTW I did order a new Switch that will be in next week for $75.00 which I will install. The relay should be the fix but I don't like to bastardize any of the electronics.
Also I beleive a grounding kit for the FD is needed. I found anywhere from 1 to 3 volts from ground to ground.
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Just to let you know I just add the one diod that connects the white wire to the green (the silver striped side on the diod is towards the green wire). And I am going to add an extra ground wire to the red wire coming off of the fan switch. And before I reinstall the switch I am going to clean the internal contacts and stretch the two springs back out to add more pressure to the contact points. Hopefully this works 
I am not too greedy, I just want 3 out of the 4 fan speeds to work!
I am not too greedy, I just want 3 out of the 4 fan speeds to work!
The best fix so far is from Freddie Hebert.
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 ISC 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
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 ISC 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
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Thanks for the info Chuck I will do this mod tonight....but since I have already connected the diode from the white wire to the green, is it ok to leave it attached and add this relay mod?
I will do this mod tonight....but since I have already connected the diode from the white wire to the green, is it ok to leave it attached and add this relay mod?
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Thread Starter
Joined: Apr 2002
Posts: 2,194
Likes: 2
From: Dayton, OH
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
Joined: Oct 2001
Posts: 414
Likes: 0
From: South Carolina
**pheew** I really didnt feel like taking my dash apart again to get to that diode. I will just leave it in there (to help the switch produce the best ground as possible) and then add the relay fix to add a better ground to the ecu (post#65). This is probably the best fix for the a/c not working properly with the PowerFC.
Add a diode and relay = proper grounding for a/c system for PowerFC!
Add a diode and relay = proper grounding for a/c system for PowerFC!
Piston Convert
Joined: Jan 2007
Posts: 47
Likes: 0
From: Severn, MD
Maybe somebody can clue me in here, I'm new to the FD service manual and wiring diagrams. Getting very frustrated. Looking at the wiring diagrams it lists wire 1E as being on the 20 pin ecu connector, 3rd from the end, just like explained above. But there is no color coding diagram or anything useful...they lump it all together Does ANYBODY have a pinout diagram ONLINE of the ecu? I've read thru probably 100 threads of people asking for it and nobody takes the 5 seconds to shift+printscreen and upload it. They all take the lazy way of directing people to the factory service manual which is pretty dishartening. Can anybody help me? I also need ign +12V.
Last edited by Justin311; May 27, 2007 at 05:28 PM.
Senior Member
Joined: Oct 2002
Posts: 526
Likes: 5
From: Atlanta
I'm sure I can figure this out when I have enough time... but it seems there are enough people with this frustrating problem that a "how to for idiots" complete with pictures would be helpful. Thanks.
