Luvs2slide

Car is a N/A S15 with a s13 SR20det swap. I've already re-wired the entire engine harness and EVERYTHING works, BUT the A/C.

I'm utilizing the original A/C components from the s15 including all lines, compressor, drier, etc.

All fuses and relays have been checked and are fuctional.

I've got my s13 ECU hooked up to both the A/C relay and dual pressure switch. Pin 106 from the s13 ECU should be the ground needed for the A/C rekay to energize and power on the compressor...However, at pin 106, I'm getting a positive voltage with the engine on. ALso I'm only seeing approx 5 volts at the pressure switch (A/C button On I see 6.5 volts); The FSM states it needs to see 12 volts so there is a big voltage drop happening.

There is sufficient freon in the system, and when I put +12Volts from the battery to the compressor, the clutch engages and I get ice cold A/C.


Any clues as to why I am not getting the needed ground from pin 106?

These are from the S15 FSM HA section.

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Mikester

Sounds like the ground wire going to pin 106 does not have solid continuity to chassis ground; or is making slight contact to power somewhere. Have you verified 12V sitting at the relay?

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codyace

If you jump the pressure switch (effectivly tying the input/output together, you could do this with a paper clip) does the system work? Does the light in the hvac button come on as well?

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Luvs2slide

Mikester: I have pin 106 on my ECU hooked up in place of where pin 11 is in the picture. The ECU provides the ground, and everything else works so I'm pretty certain the ECU is grounded properly.

Cody: I havnt tried jumping the pressure switch, but I did the paperclip method on the A/C relay (pins 2 & 1) and the compressor kicked on.

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codyace

At lest you know the power routing is ok wire wise, but now it's down to sort out where that pesky switched signal defunct.

Check to see if it's getting power to the pressure switch, and getting out. If it's not coming out, jump it and see if it works. That eliminates the switch.

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Luvs2slide

I'll give that a shot Cody. I'm very curious why the ECU is putting out positive voltage on pin 106 (pin 11 the ground in the pic) instead of a negative signal. I have tried 3 ECUs already to no avail, no i'm thinking it's not because of the ECU. From what I've seen, the s15 is very similiar to the S14s...And I'm pretty sure the s13 A/C system very different than S14. Is it possible to turn that positive signal out of pin 106 of my ECU into a negative signal?

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Z28ricer

At pin 106 you will see a 12V+ if you're checking with key on and the ecu isn't getting a signal requesting the a/c, because of the coil in the relay, the 12V you're seeing is coming from the L/OR wire at the other side of the a/c relay.

What did you touch ? What other wires did you change to attempt to make this work ? So far I only know where you've connected the Green wire the normally goes to the S15 ecu to the pin 106 at the S13SR ecu.

Z28ricer

What you should do, and will make the system work:

Connect the LG/B coming from the A/C switch at terminal 3 to the R of the Dual pressure switch

You can do this at the connection that will become the used to be thermo amp, unplug it, loop those together, then connect the L/B output from the dual pressure switch to L/G pin 41 of the S13 SR ecu.

Luvs2slide

Z28ricer: thanks for your input. The only wires i have messed with so far are the two ECU wires ACRELAY and ARCON and then I ran a separate wire from the compressor to the L/R pin 3 at F4 plug.

I'm really trying to keep the system working like OEM if at all possible.

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Z28ricer

Apply +12v to the SR ecu pin 41, you should then see the 106 output a ground to trigger the relay, the way I told you to rewire it is the way to get factory operation out of what you have, the s13sr ecu doesn't have the thermo amp input, the way I suggested you wire it is the same as the 97-98 S14 which doesn't use a thermo amp and I've wire it this way in 97-98's to have the s13sr ecu control it.