Questions about electric fan w/ AC compressor
07-03-2020, 02:20 PM
#1
Questions about electric fan w/ AC compressor My setup: 1978 Caprice. 2004 Avalanche 5.3 LM7. Sanden 508 Compressor. 1996 Caprice Condenser. 2000 s10 high pressure AC line using pressure sensor to power two electric wires wired with 3 relays for off/low/high speed (low is both fans on low, high is both fans on high). PCM is 2006 Express Van so it will accept the 12v request signal for the AC and is flashed as a 2004 Avalanche with the fan controls modified by tuner.
This setup is supposed to function as a stock setup would in reference to when the electric fans come on. With a tech II hooked up I have found that only the low speed electric fan comes on when the AC relay is engaged. The high fans don't kick in until the high side pressure hits around 250 or so (give or take). I thought the electric fans were supposed to run on high anytime the AC was turned on, is this wrong? I also drove down the road and saw that according to the Tech II the signal for the electric fans does not cut off at speed. I thought these were supposed to cut off when a certain speed was reached. Also, in watching the compressor (AC request signal), I thought it was supposed to cut off when the accelerator was pushed to the floor, but I'm not showing that this is happening according to the tech II. Maybe I'm misunderstand and that the AC relay request is always there and the computer will override it under hard acceleration, and maybe the fan relay requests are always on but they are overridden by the computer at highway speed.
Could someone confirm how the system is supposed to work from stock so I can figure out of my setup is not working correctly.
Thank you,
Brandon
This setup is supposed to function as a stock setup would in reference to when the electric fans come on. With a tech II hooked up I have found that only the low speed electric fan comes on when the AC relay is engaged. The high fans don't kick in until the high side pressure hits around 250 or so (give or take). I thought the electric fans were supposed to run on high anytime the AC was turned on, is this wrong? I also drove down the road and saw that according to the Tech II the signal for the electric fans does not cut off at speed. I thought these were supposed to cut off when a certain speed was reached. Also, in watching the compressor (AC request signal), I thought it was supposed to cut off when the accelerator was pushed to the floor, but I'm not showing that this is happening according to the tech II. Maybe I'm misunderstand and that the AC relay request is always there and the computer will override it under hard acceleration, and maybe the fan relay requests are always on but they are overridden by the computer at highway speed.
Could someone confirm how the system is supposed to work from stock so I can figure out of my setup is not working correctly.
Thank you,
Brandon
07-08-2020, 08:59 AM
#2
