S2000 AC not Working

[SCS2K]

Can you please review my tune and let me know if it looks correct? I am having an issue where the AC isn't working. I have checked the components and they all work (if I jump the main relay the compressor kicks on and it works just fine). The light for the AC on the dash does come on as well. So I am at a loss of what the issue is. It seems like everything is working except the signal to turn the compressor on.

2004 S2000 with Vortech Supercharger, methanol injection, RSX ECU, and Kpro

[Spunkster]

Have you checked the underhood AC relay, as I have seen that cause the exact same symptoms?

[SCS2K]

Yes I did. I swapped it with another relay and still had the same issue.

[Spunkster]

VTP is what it uses for the AC on an S2000. What is the serial number on the K-Pro board inside the ECU?

[SCS2K]

The serial number is 37820-PRB-A05

[Spunkster]

I need the serial number on the K-Pro board inside the ECU.

[SCS2K]

Sorry about that. Hopefully this is the number you're looking for: 40804

[Spunkster]

When was the last time that this was working?

[SCS2K]

I bought the car from a guy who had a tuner install it a year before. From what I know the AC never worked with the Kpro

[Spunkster]

Are you sure then that the AC is actually functional in that car?

I would recommend trying that ECU in another S2000 running a K-Pro to verify that way.

[SCS2K]

I jumped it and the AC did work just fine. So I know the hardware works. It's just not getting the signal. Any other suggestions on testing the signal coming from the Kpro besides trying to find another s2000. I'm not sure if I can find access to another one.

[SCS2K]

I went through a couple troubleshooting procedures to try and determine the fault. I tested the compressor clutch relay itself and the fuse block and both passed. I went to the thermal protector on the ac compressor next and found that to be functioning ok by jumping the pins for the compressor clutch on the fuse block. I ran if for a couple minutes this way to make sure I was getting cold air from the AC system to make sure the system wasn't low causing the pressure switch to fault not allowing the compressor clutch to work. This checked out fine too so I moved to the AC Pressure switch and the voltage at the connector was present according to the service manual (section 21-31). I also ohmed out the pressure switch itself and it showed serviceable too. This process and the service manual are both leading me to it being a fault in the ECU. I tested for voltage at pin 17 and 27 like suggested in the manual and both came out at 0. Any suggestions to further test the ECU?

[Spunkster]

The K-Pro for S2000 uses the VTEC Pressure input for the AC to work as it says on the misc. section.

While datalogging you should be able to ground pin b9 (C10 S2000) and you will see VTP, turn off and the ACSW, ACCL and FANC all turn on.

[spoon.ap1]

I had this same problem a month ago. Take your AC relay out and pry the prongs back. You may have to use a different trigger for your water pump.

[SCS2K]

Do you mind explaining a little more about using a different trigger for the water pump and what you did?