A/C Issues on 96' DIYPNP
 

Hello everyone,

I'm hoping to get some help on why my A/C isn't working. My car is an N/A 1996 with bolt ons and FF injectors, and the DIYPNP board is V1.5B with MS2E 3.4.1 code. Here's how it's setup:

1b and 1g are jumpered on the connector board.
1b also goes to ALD.
1k goes to the input on input 1.
Input one output goes to AD2.

The board wasn't originally built for AC and so I had sent it off to the person who did build it (nobody on this forum) for it to be set up. They're not sure why it's not working.

https://cimg8.ibsrv.net/gimg/www.mia...394270018.jpeg
https://cimg0.ibsrv.net/gimg/www.mia...88a1b843b.jpeg
https://cimg1.ibsrv.net/gimg/www.mia...71b7dc308.jpeg


I've got tunerstudio setup so that on the AC Idle Up menu like this, and have nothing set for the ALED port on the programmable on/off menu:

https://cimg3.ibsrv.net/gimg/www.mia...22aa91d07b.png

When I turn on AC neither the fan or compressor kick on. I've switched back and forth between the stock ECU to verify that everything is functional and AC does work with stock ECU. I should also mention that when I have KOEO, in the I/O test mode forcing ALED on does kick the AC fan on. Any help on this would be greatly appreciated, this is a street car and I need to have AC working. I've looked around a little bit on the forum and I have a few hunches on maybe it needs to be added to a relay, or potentially the gslender firmware, but I don't want to make any changes before checking here. Hopefully some fresh eyes on the issue help solve it.

Thank you all in advance!

wiring is correct.

never used adc2 for a/c input, but it sounds like the input isn't switching.

the 5v is from the input circuit, the MS will activate the output when that drops to ground. sounds like the switch isn't dropping it to ground for some reason. Measure 1K to see if it grounds out when switched on.

what happens if the a/c fan speed is set to "1", and not "4"?

I see, and you're right. I've tested 1K to see what's happening at each fan setting with AC on and off.

1K
Fan setting 1 - AC on voltage .6V; AC off voltage 8.2V
Fan setting 2 - AC on voltage 1.24V; AC off voltage 8.3V
Fan setting 3 - AC on voltage 1.29V; AC off voltage 8.4V
Fan setting 4 - AC on voltage 1.83V; AC off voltage 8.4V

So the voltage IS dropping significantly, but maybe not enough. I've checked the input and output pins on Input 1 and the input matches the voltages I'm seeing on 1K and the output pin seems to consistently be around 5V.

PS thank you again for your input on this, any help is great help.

i had this issue before on my personal car and seen it in a few others-- the voltage needs to drop below 1.5v in order to trigger the input IIRC but sometimes in fan speed 4 it simply wont drop low enough.

at least on fan speed one, that should be low enough to trigger the transistor on the input circuit. Double check the solder on those legs -- very easy to join them together. It's possible the transistor is actually bad...

I've gone back and checked the connections and there are no neighboring legs on the transistor that have solder connecting them. I'll be very blunt and say that originally I had accidentally set the idle up polarity to 'high' instead of low in the settings. Hopefully that didn't cause any problem with the components.

Knowing that input 2 works I am wanting to just switch the wires over and try that, but I want to get to the bottom of this. I'm going to go over each part of the input 1 area with the multi meter and see if there's a discrepancy somewhere and then if not I'll replace the transistor. I guess it is possible that it's failed closed. I'll keep this updated with my results and if anyone else has got any more testing tricks I'm all ears.

My compressor would stop engaging often when I turned the fan to 4. Also curious why. '96

Well as a small update I wired 1k to the IN on Input 2, and switched the AC Idle Up settings so that Idle Up Input is on PE1. Still NOTHING when I kick the AC on. I triple checked that Input 2 OUT goes to PE1 and as a benchmark I had launch control working on that input before switching to it from Input 1.

I'm posting my tune up to see if there's maybe a clue there. I know I'm a firmware update behind being on MS2E 3.4.1 code but DIY has told me that shouldn't make a difference here. Maybe it's that ALED is disabled on programmable on/off outputs? CAN Settings?

Six, to your and Brain's issue on fan setting 4 maybe a small resistor could be used to drop the voltage. I don't know if that's best practice but it might work.