411 AC and cooling fan issue

[Yellow05C6]

I'm using an Express Van 411 (12212156 OS, low resolution crank) to control a C4 L98 engine. The thing is up and running great except one issue. When AC is requested, only one fan runs. The second fan kicks in (as normal) when coolant temp reaches 195. But by then AC head pressure is causing the compressor to go off line. Once the second fan does kick in, head pressure drops and compressor runs forever. Anyone have any idea how to make an AC request run both fans?

[Lextech]

Did you wire in an A/C Pressure sensor and install the correct "System" segment into your tune? It can't operate the fans based on A/C pressure if there is no sensor.

Jeff

[Yellow05C6]

Yes, the pressure sensor is in the system. I know nothing about a "System" segment. Can you explain?

[Lextech]

Can you post your tune?

Jeff

[joecar]

Yes, the pressure sensor is in the system. I know nothing about a "System" segment. Can you explain?

In the tunetool, look down the left hand side, you will see "folders" for Engine, Engine Diagnostics, Transmission, Transmission Diagnostics... etc... the last "folder" is System

( the "folders" are segments )

[Yellow05C6]

I believe I have successfully added the tune file. Silly of me not to understand "System", the file is set to Y-Body with low resolution crank. When scanning, the ECM correctly reports against the Air Conditioner Pressure Sensor Voltage PID.

[Lextech]

Try this and see if it helps.

Jeff

[Yellow05C6]

Wow, it works. But when I compare your mod to my original file it comes back as zero changes. Can you tell me what you did?

[Taz]

The A/C System configuration was changed from ground activation (A/C request = grounding a 12V circuit) using Low & High A/C Pressure Switches, to ground activation using an A/C Pressure Sensor.

The parameter is not available in EFILive, which is why you will see no difference during a comparison of the two tunes.

[Lextech]

If I tell you, I'm going to have to kill you. Taz is correct. The parameter is not in the "As Purchased" EFILive software.
I'm glad it worked out.

Jeff