Here is what I've got going on. I replaced the orings, baked the reciever/drier, checked for leaks, vacuumed and charged the system with the amount reccomended by one of the vendors here.

The a/c works GREAT, when it is operating that is. The car runs cool and passes with the wife's seal of approval.

The issue appears to be the "A/C signal" to the PFC, is the switch/sensor check screen the little dot does not stay solid with the A/C button on. IT does seem to work better at lower fan speeds and stay on longer periods of time.

I remember a thread talking about this exact problem, with a ground being a possible solution or a new fan speed switch.

I have tried searching for it with the search function, but I have been unable to find it either due to a failure in searching or my own, lol.

Thanks!
Vince

 

https://www.rx7club.com/power-fc-for...-c-fix-435420/

Hope this helps!

 

That's the exact thread I was looking for!

Thanks! Will report with results when fixed.

Vince

 

does it work?

 

Replacing the fan switch worked for me, I now have compressor function on all fan speeds. I was not comfortable revising the wire harness, just my opinion.

 

hi, mind to share how does it look like? also, where can i get it? do u think i dismantle from those 99 spec half cut will work for those 91 spec FD3S?

 

The issue is that the switch seems to develop internal resistance that confuses the PFC so that the compressor won't engage. If you are using a used switch, the problem may just continue since whatever causes the problem happens over time and a used switch is still a used switch. Just get a new one. A new switch is about $80 USD, replacing it requires that you disassemble the HVAC computer, it's pretty straightforward once you have the HVAC panel out.

I also used dielectric grease on the plug contacts to minimize resistance there, too. I have started using this on all the contacts of my FD as I service or repair something. This car has one of the weakest, worst electrical systems of any car made in the last 30 years probably!

 

stickies this

 

I forgot to reply with my findings. I took my fan switch apart and the copper inside was green! I polished it up until it was shiny and reassembled it with dielectric grease.

Afterwards, I now have a solid A/C indication in fan speeds 1, 2 and 4. 3 does not show up at all. the issue must be elsewhere in the dash harness. I'm thinking it must be one of the grounds. The fan itself is also kinda wimpy, so it leads me to believe it has poor ground.

I will need to remove dash to see why I do not have heat, I think the blend door is broken. So, while I'm in there I'll address all of those grounds and disassemble the blower fan to service the brushes and lube the bearings.

Vince