speedjunkie

iTrader: (3)

I changed the output (ECU to AC relay, Y/B wire) from A4 to A19, one of the fuel outputs, at Chris' suggestion. He remoted in and changed the settings and we tested everything and it worked like it was supposed to, although that's with the pressure switch connector jumped, which I then realized I already knew operated normally before when it's configured that way. After we got off the phone I tested it again the way I know it has an issue and the issue is still there. I'm going to verify tomorrow night with the multimeter at the back of the ECU that the output wire is still providing ground at all times with the car running.

speedjunkie

iTrader: (3)

I hooked up a relay and wiring external to the stock wiring and AC relay, but I must be missing something else because this time it didn't come on automatically, but it didn't come on at all with the pressure switch jumped and the AC turned on. I even tapped off where the power actually comes from. I bought a new relay from Ray Crowe and pinned out the stock wiring to make absolutely sure all the wires were going to the exact pins they do with the stock wiring so I can test it again.

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fstfwd

iTrader: (1)

Sorry to hijack the thread but I'm troubleshooting the A/C system as well. Wondering if you can share the part number for the AC Relay that you're using? This is the one located 2nd in from the right (in the box) at the front of the car, near the intercooler. The used one I have doesn't have the part number on it anymore. It fits but doesn't kick in the clutch on the compressor. At the moment I'm using a manual relay (which has an on/off toggle on it), to override. When that is thrown to "on" you hear an audible "click" and the compressor works great...

It would be preferable to find a relay from a '94, if they are different than a '93 as I've put a '94 A/C compressor in my '93 and upgraded to the R134a refrigerant.

Additionally, if anyone also knows what the part number is for the pressure switch that's a bit farther up the circuit, that would also be amazing.

Many thanks!

speedjunkie

iTrader: (3)

67-7403 - relay
According to the parts manual, the same relay is used on both the MANA and Denso system, and it looks to be the same relay between 93 and 94 as well.

For the pressure switch, FD16-61-503, Ray told me it's NLA. I've started looking at other options for a binary pressure switch. Some earlier Nissans used one that I think might work, but I haven't verified yet if the thread pitch is right or if the pressures are right.

https://www.summitracing.com/parts/fss-20979
I believe this is the link to the one I was looking at. It looks almost identical to the one in the car aside from the connector. That's not to say that it's completely correct (N/O, the right thread pitch, correct pressures), but considering it's from the same time period and looks pretty much identical, I'd say it's worth a shot to at least check into.

fstfwd

iTrader: (1)

Thanks, I appreciate the info – I'll take a closer look!

marshun

hows this going?

speedjunkie

iTrader: (3)

Meh, lol. I got the relay from Ray a couple days ago but I haven't had time to mess with it yet. Maybe this weekend. Although I don't foresee it being any different with this relay than it was with the last one.

speedjunkie

iTrader: (3)

I finally tested it with the new, stock AC relay and wired it exactly how it's wired in the stock harness, and it is still turning on AC automatically, and it still will only shut it off if I jump the pressure switch. So it's looking more like it's the ECU and/or tune, but since the brand new ECU did the same thing, I'm leaning towards it being something in the tune. I just don't see how it would have changed suddenly just by jumping the pressure switch.
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marshun

i know youre in this thread.
but did you see the last post? maybe that could help. i'll have to remember this when i finally get the haltech going
https://www.rx7club.com/3rd-generati.../#post12465335

speedjunkie

iTrader: (3)

Thanks! I may have seen that, I'm not sure. At that time I hadn't started digging into this problem again so I probably glazed over it. I'll have to look into that. I don't think the problem is exactly that since it was working before, but it could be close. My buddy on another forum suggested it might be the blower motor resistor not allowing the proper voltage. I think the resistor is good because the voltage readings are pretty close to what they should be, but it's a cheap enough part to try with some swap-tronics anyway lol. And if it doesn't fix the problem, I have a spare.

The ECU provides a ground to the AC relay even if the input wire (1E from the AC switch, pressure switch, and thermoswitch) is disconnected, so for the blower motor resistor to be the culprit, I would think it has to be providing basically no voltage and I know it is. But I'm still going to try it.

Being that I wired it externally with a new relay and the problem still occurred, I believe the problem is not in the wiring. Not in those circuits anyway.

speedjunkie

iTrader: (3)

The Syvecs gave up the ghost last fall. Stopped powering the fuel pumps and most likely the ignition as well, since it wouldn't fire even when it had fuel. So I went about swapping to a Haltech Elite this winter, and I figured I would finally see if the issue was with the ECU or what.

Last winter I rebuilt two of the compressors I have, and I replaced the expansion valve and cleaned the evaporator, which wasn't all that dirty. I replaced the condenser again to start fresh, and flushed all the lines and tested anything I could test within the circuit, aside from the AC button itself. And since my ECU fried last fall, I also replaced the front harness with one I bought from Jim Thompson just in case it was the harness after all. And with the new Haltech, and possibly the front harness, all the issues are gone now and AC is working great. I took it to my buddy's shop and had him charge it with R134a this time since he's a professional and I got tired of ruining compressors.