Will the power fc still control the a/c on a FC? The reason i ask is because my a/c worked fine before i installed it and i never tried it after the power fc install. The a/c light comes on but the compressor doesnt and i didnt want to spend money to have it charged if this was my problem. Thanks

 

Compare the FC A/C wiring to the FDs and then read up on the best FD-PFC A/C fix using a relay. It can be made to work without much problem.
That is if you are DC circuits compatable.

 

Well looking at the 94 wiring diagram, it looks like the a/c relay output wire is y/b. Does that mean yellow/black i assume? My problem is i dont know which pin or wire that would be on the power fc. I read a few write ups and it says its the third wire from the end on connector one. Which one is connector one? And thanks for the help.

 

Use the FD FSMs.

 

I am but it still doesnt help me as i dont have fd wiring. I just need to know which pin on the power fc because i cant go by the color.

 

Ive been looking at pages 71-72 and it shows the wiring, but it doesnt help me. Does anyone know, which pin/wire if looking at the powe fc, is the one i need to wire in to?

 

The A/C main relay wire is 1L it is blue/white stripe it does not change position exiting the PFC to the S5 harness. The refrigerant pressure switch wire is 1E on the PFC and switches position to 1O on the S5 harness it is blue/orange stripe.

 

Thanks alot!

 

friend of mine has no problem with A/C on his s5 AP Engineering PFC...

 

And in most cases the FD PFC runs the A/C without problems, but then there are the FD owners that have an issue, so there is a fix. Looks like there are FC owners that have the same issue, wouldn't matter if it was AP or the FD unit being used.

 

Well i just took a look at everything on my car and those two wires already match up through the Banzai harness. I checked all the connections for the a/c and everything is hooked up. Nothing has been changed on the a/c system since i took the stock ecu out and installed the pfc and it used to work great. I dont really know where to go from here. Anyone have any suggestions? Thanks

 

Find a real FC mechanic/tuner to work on your car, or find someone who really knows auto electronics.

 

Thats got to be one of the most unhelpful comments ive ever heard. Since your such the expert what would the problem be? Thats right you dont know do you. Everything is hooked up as it should be, same as it was with the factory ecu and it still doesnt work. Its getting the signal from both the a/c relay and the thermoswitch(wire 1o), so your right i dont know what the problem would be. Im very knowledgable and i dont need your ignorant comments.

 

Sometimes you have to look through the section to find the answer, the A/C issues have been discussed over and over. Here is a link from a thread that is entitle A/C fix that is located 12 threads under this one.

https://www.rx7club.com/showthread.p...ghlight=ac+fix

 

my old plug and play Megasquirt did not have support for controlling the A/C, so I had to bypass the ECU altogether. I don't remember the pins exactly (and it was an S4) but I cut the two wires going into the ECU harness plug (A/C signal from logicon to ECU wire and the A/C signal from the ECU to the compressor) and soldered them together. Thus the logicon directly switched the A/C compressor, and I lost the functionality of A/C idle up and turning off the compressor under load.

I suggest you try this, not as a long term solution, but just to see if it would work so you can narrow down the problem. Those two wires should be on the Banzai harness I think... cut them and splice them together temporarily and see if the A/C compressor cuts on then. Then you may need to figure out if you need a relay or something else to get it to work.

 

see s5 FSM page F2-77

hmm... on a series 4 car you would jumper pins 1E and 1F on the ECU plug to bypass the stock ECU completely. That is what I did on my Megasquirt because it had no A/C control.

Looking through the FSM for the s5 turbo ECU (not sure if you used an N/A or turbo harness), it is S5 pin 1O (letter "o") that has the signal from the A/C logicon switch and 1L that goes out to the relay. It switches from ignition +12v to ground when activated on both pins. So if it were me, I would either jumper or cut and solder those wires first and to see if the A/c turns on when the PFC is bypassed.

If it does, I would verify that the A/C is showing up under "sensor check" on the commander when activated (at least I think it should show up there as long as the PFC sees the ground on s5 pin 1O), then verify that the PFC is in fact switching ground. That would be done by first checking to make sure there isn't +12V coming out of s5 pin 1L when the A/C is switched on. There should only be +12V coming from pin 1L when the A/C is OFF. Then I would check to see if ground is coming from pin 1L by placing the black lead of the multimeter on s5 pin 1L and the red lead on something that is supposed to see +12V. If there is ground coming from the PFC it should complete the circuit and you should see +12v on the meter.

From there I would proceed to I would try using a relay to trigger a stronger ground. The relay would be wired like so:

85 pin --- comes from s5 pin 1L, ECU side.
86 pin --- goes to ignition +12v
87 pin --- goes to a known good ground
30 pin --- connect that to the harness side of pin 1L .

Thus the ground from the PFC switches the coil on the relay, which in turn pulls the chassis ground out on to pin 1L and to the A/C relay. If ground isn't even coming from the PFC but pin 1O (input signal from the logicon) is behaving correctly, I'm stumped.

That's how I would hypothetically attack it at first, just thinking about the problem for a few minutes. Good luck.

 

ok I just re read your posts... I see that you have already looked at some of the stuff I just mentioned. You do have a confirmed ground coming from s5 pin 1L, is that what you're saying? What I just proposed was similar to the "official" fix, except it is on the output side of the PFC instead of the input side. By trying the bypass diagnostic test I proposed, you will see if the ground signal coming out of the PFC is too weak to switch the A/C relay.

 

Well i tryed just bypassing the ecu and that didnt work which leads me to believe its the original a/c relay. I went ahead and did the other checks you mentioned and i see 12V on 1L no matter if the a/c is on or off. I checked to make sure the pfc is grounding and it is. So im down to thinking its my factory relay. I went ahead and wired up a relay to send a better ground and still nothing. Couldnt i just bypass the factory wiring and make a new circuit? Just use the thermoswitch wire coming off the compressor and the wire coming off the logicon. Ive called around and nobody lists a factory a/c relay so i dont know what to do. And thanks for all the help.

 

I'm not sure I understand what you are saying. According to the s5 FSM page F2-77, s5 pin 1L (output from ECU) should see +12v with the A/C switch off and "under 2.5V" with the A/C switched on. s5 pin 1O, the input to the ECU, is the same: "below 2.5v" when the A/C is on, and "Approx 12V" when the A/C is off. Ground and +12V are opposite polarity, you can't have them both at the same time in the same place.

If you are seeing 12V on the output side (s5 pin 1L) no matter what, the PFC is not generating the correct output, either due to internal problems in the PFC or due to an improper input signal on pin 1O. If Pin 1O is not behaving according to voltage specs, you need to go to the refrigerant pressure switch, as is mentioned in s5 wiring diagram section G-2a, page Z-76. Look through there and trace the circuit to figure out which component is misbehaving.