Hi. I have an 86 Rx-7 N/A. I did a turbo II swap, Put an 88 engine in it. Car runs and drives great.
A couple weeks ago my a/c clutch quit engaging. I changed the a/c relay that is under the hood. I put a new Pressure switch, recharged system,new Compressor And put a new a/c clutch. I checked all the connections with a volt meter, they all seem to be working good. The engine kicks up idle, but clutch doesnt engage.
I have been trying to fix it on my weekends spent 3 weekends messing with it almost all day. I havent gotten anywhere . Any advice will be greatly appreciated.

 

I'm not exactly sure, but there is a way to turn the compressor on manually to check and see if it engages, there's a really big thread somewhere on it.

 

At pin 1E of the ECU measure the voltage w/the AC off, but blower motor on, and then w/the AC on and blower motor on.

 

The compressor is new and it will click on if I jump a positvie wire to it. With the blower motor on and the a.c on/off the volatage stays the same.

 

Oh crap let me double check I think I looked at 1F.

 

Ok I checked 1E loses all voltage when I turn on a.c switch on and 1F the voltage stays always stays the same

 

When I checked the pins going to the a.c relay under the hood it has 4 pins. 3 pins are powered and one goes to the compressor. the relay is not getting any ground. Im not sure what could cause that.

 

Pin 1F is responsible for sending the ground to the relay.

 

Do you know what could cause the 1F pin to not send ground to the relay?

 

W/the A/C on, the relay should have voltage on the Blue/Black wire, Red/Yellow wire and the B/W wire plus a ground on Blue/White wire. I gather you have voltage on this wire and no voltage on the B/W wire.

You stated that at pin 1E that the voltage dropped w/the A/C on and the blower on. How low did the voltage drop? The FSM says it should read less than 2.5 volts. What does yours measure? Perhaps you can manually jumper a ground to pin 1E while plugged in and see if this makes a difference.

 

The voltage dropped to no power at all at 1E. 1F doesnt change. Im not sure if thier is another a.c relay... the only one I checked is under the hood it has 4 pins 3 of them are powered and the power never changes and the other one goes to the a.c clutch.

 

I tried to jump a wire from 1E to 1F and it works good, but when the engine is running the a.c compressor will turn on when I turn the blower motor off.

 

Because when you turn the blower off the ground on the wire you are using reverts to 12 volts.

 

Thanks for the help satch I apreciate it. Do you know why the 1F blue/white wire wont ground the relay, Right now its staying at 12v blower motor and a.c switch on/off. The relay is recieving constant power from that wire too.

 

The cooling fan relay turns on when I turn on the a.c but no compressor everything is working good except for pin 1F wont ground.

 

The only explanation I have is there is something wrong w/the ECU but I could easily be wrong. The ECU only has two pins directly related to the A/C and one of them checks out okay. To understand why the other pin, which is an output wire, does not work as it should is beyond me. I don't really think it's possible but if the plug housing the two wires were disconnected from the ECU and the key were to on is there perhaps a voltage reading on the Blue/White wire running to pin 1F?

 

It seems to work good when i turn on the a.c the idle kicks up and the electric cooling fan turns on, but the compressor wont turn on. Pin 1F wont put out a ground its driving me nuts. I put another ecu in it, but nothing changes, is thier something that is supposed to go to the ecu that says the engine is running? Do you know a way I can jump a wire to it from the a.c button to the clutch, that wont turn on the clutch with the blower motor off?

 

Im not sure if 1f Is getting power ungplugged. Ill have to get back to you on it tomorrow. I really apreaciate the help. Thanks!!! But I believe that it is. Ill double check thing is driving me nuts. I cant get nothin else done on the car cuz that dam a.c

 

You would need to jumper a ground wire to the Blue/White wire which runs to the clutch and run it through a toggle- on/off switch and control it that way. Again, if the plug housing the Blue/White wire were unplugged from the ECU and w/key to on is there voltage on this unplugged wire? There are two wiring diagrams for the A/C as one is for NA and the other for the turbo but it doesn't appear to be a difference w/respect to pins 1F and 1E.

And another thing to check is to unplug the relay and check for voltage on the Blue/White wire w/the A/C set to be on and see if there is still voltage present on the wire or not.

 

W/the relay plug disconnected and the A/C set to on (w/key to on and blower motor on) check each of the four wires and see what you get and specify what each wire is getting by its color code. Blue/Black should have voltage, Red/Yellow should have voltage and the other two wires should not have voltage. And w/the relay plug disconnected turn off the A/C and see if there is a voltage change on the Blue/White wire.

 

If the ac fan motor turns on why don't you just wire the compressor clutch to that. .. DONE

 

Ill probably will have to do that. Im trying to avoid running wires everwhere I dunno why that damn thing wont work. Im gonna check it out this weekend. The clutch kicked on today for a couple seconds then quit. Is that the only relay for the clutch?

 

You need to test the relay itself while unplugged from the car. And you have yet to figure out whether one of your wires is damaged and receiving voltage from a neighboring wire.

 

I gotta fidle with it in the morning hmmmmmm. When its unplugged from the ecu there is no power going to 1F. I put another ecu in it, for trial and error and it did the same thing. I stripped the harness in the front of the radiator and it all looks great. Do you know what the two black rubber rectangles do that are in the harness? One is in the red/yellow wire and the other is in the blue/orange wire. I grabbed some off a car at pick n pull and swapped them but no difference.

When everything is unplugged there is no power to the blue/white wire... Do you know which wire I can jump from pin 1F to the a.c switch in the control panel that wont turn the compressor on when the car is running.

I tried the light green/white wire but when the car is running everything turns on the a.c compressor when the blower motor is off.

So do you think that is what I have to do is jump a wire to pin 1f when its unplugged from the ecu?

 

I wouldnt want something wired directly to the clutch. I want to try to keep it so the the clutch cycle switch and the pressure switch still works. Thing is driving me nuts it came on today for a couple seconds. I put everthing new for the a.c. The goes to the a.c button, clutch cycle switch, ecu, psi sensor, relay and clutch. Nothing else runs it?