Hello,

I hope Chris can help me with this problem. I have already searched and checked around but still confused. BTW, I got my power fc from rx7.com. I turned on my a/c but I'm not getting cold air and took my car to shop and found out that my high and low pressure is same. when i turn on my a/c, rpm goes up and there is some change in engine load. I'm not 100percent sure if a/c compressor is working. Do I need to change expension valve or is this caused my power-fc??

thanks

 

This is a known issue. Blame Mazda, not RP.

https://www.rx7club.com/power-fc-forum-47/new-version-powerfc-faq-573647/

Check that FAQ out. It taught me a lot

 

This issue could be a PowerFC issue or a general AC problem. I'm assuming that the AC system functioned fine immediately before the PowerFC was installed. If so, check to see if the system is working on any fan speeds. Also, look on the PowerFC Commander on the sensor/switch check page and see if the AC switch illuminates when the AC is engaged (try all fan speeds). It is most common to have an issue with fan speed three, but others have been known to be an issue also. The root of the problem is insufficient ground signal to the AC input of the PowerFC. There are several solutions we will discuss after more information is given. Hope this helps.

 

You'll find a fix in the PowerFC Section of the forums: THE power FC A/C fix!!!

 

Copied from the "Power FC A/C Fix!" thread referenced above:

"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 or similar heavy-duty 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"

 

Sorry to bring back this thread. But tried emailing Freddie, seemed like the email domain doesn’t work anymore.

I’ll copy paste the question here:

So I took apart the hvac dash per original post saying add by tapping an extra ground to the fan switch ground wire and cleaning off the switch. (Do they still sell new fan switches?)

I popped it out and cleaned it but putting it back together it seemed to be reverse in polarity (fan switch). I don’t know how I could have reinstalled that switch piece incorrectly.

Anyway those did not help with getting the compressor back on. In any fan speeds w the AC button on.

I looked in the power fc sensor reading and the AC doesn’t seem to be high lighted when pressed on.

Do you think doing the relay mod that you mentioned by the ecu would work? Any 40 amp 12v 4 prong or 5 prong?

thanks guys

 

Post #5 simply can not be more clear about what to do. What you're talking about with taking the dash apart and adding a ground I have no idea. Simply follow the directions on post #5.

 

Just recently did this mod myself and it worked perfectly. The only real question here is whether to use the Banzai patch harness or cut the OEM harness... I would recommended getting the patch harness to keep it clean.

 

the issue is fitting the patch harness in that tight space under the panel. modding the stock harness for this can be done cleanly.

 

I recommend the patch harness, it's so hard to work in that tight space under the dash. I'm getting old =D

 

250$ for a patch harness to install a 20$ relay for the sake of convenience. some you guys discretionary income is truly impressive lol