The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Engine & Drivetrain > LSx Swaps

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 02-19-2021, 06:48 AM   #1
rocketmench
Registered User
 
Join Date: Jun 2010
Location: Granger, Indiana
Posts: 3
Re: AC wiring

Thank you LS1Nova! I've been a lurker for some years now as I plan my restoration project, and your posts are always helpful.

I set the A/C request mode to "Analog", I did not try "Analog Cycling". As I understand it, "Analog" mode requires a pressure sensor in the A/C line which controls a continuously running variable displacement compressor, as opposed to a simple pressure switch for the "Analog Cycling" mode which presumably uses a fixed displacement compressor that is switched on and off.

To emulate the pressure sensor with the appropriate pressure reading, you can either add a roughly 70-80 kohm resistor between I believe C2 14 and C1 45, which creates a voltage of about 2.5-2.6V at the C2 14 (the resistor acts as a voltage divider with the roughly 70kohm internal resistor at C2 14), or just directly input a voltage at C2 14. I did the latter.

As for difficulty level of the actual soldering, I was expecting worse. Using a basic soldering iron with a reasonably small tip, it was not too difficult to remove the one resistor, and add the necessary components. Taking care to use flux and basic good soldering techniques was all I needed. I did this on 2 pcm's without problems.

The coolest part was in observing Fan 1 come on a soon as I applied the 12V to C2 17 to request the A/C! Also, adjusting the potentiometer to change the emulated coolant temperature, I could cycle Fan 1 and 2 on and off at will.
rocketmench is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 12:20 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com