E-fan controlling on 02 Chevy truck

[aaronr]

I have my E-fans set-up to be controlled 100% by the PCM. The fans are working fine with the tempter set points. I can't get the fans to come on high when the the A/C high side pressure get above 200psi set point. I was told that the 02-03 pcm can not control those set-point even know these set-point are in that 02-03yr tune file. I was also told if I get a 04 PCM that it was wired internally able to work those set-points. Can anybody verify this info for me?
Thanks

[Lextech]

The 2002 trucks with the 512kb, 12200411 PCM use a switch type of A/C system that does not control the fans based on A/C pressure. The A/C type is 3 on the trucks. The 2002 F-Body uses a type 2 A/C system and a sensor. The A/C type cannot be changed with EFILive as far as I know. I have set my truck up with the type 2 system. I am running a 2002 O/S. I am sending you a PM. I "might" be able to help you get it sorted.

Jeff

[turbo_bu]

Lextech,

If you can help to sort this out, could you share what needs to be changed? I am doing a standalone in a 56 Chevy for my dad and would like to setup his electric fans the same way. The donor engine / harness that I am using is from a 1/2 ton truck. I did not realize that you could setup the fans to trigger off of pressure on a 512 kb PCM. I thought you had to use the 1 MB PCM from the 04 and newer trucks.

Thanks,

Darren

[Lextech]

Hey Darren,
I have done it to my 98 GMC running the 12200411 PCM. I need to check into the wiring for Aarons 2002 truck.

Jeff

[aaronr]

Darren,
2000-2003 trucks can turn the fans on and off of by the temperature set points on pin 42 and 33 but my issue is the fan pull good amount of CFM on low that they hardly come on high. Then the pressure on the high side of the a/c start to climb and a/c air starts getting warm on the realy hot days. I live in AZ so summers are quite warm 105* to 115*. This was the reason i was trying to get the pressure sensor in there to be able to get the fans to come on high when the pressure set points were met.

Aaron

[Aloicious]

I run my MarkViii fan in my '96 truck with an '02 12200411 512k LS1B PCM. I'm using a LS1 A/C pressure sensor to control the fan based off the A/C pressure reading. like Jeff mentioned, the switch type A/C system doesn't actually give live A/C pressure feedback to the PCM, they're just high side and low side on/off switches that control it...you shouldn't need to change PCMs at all, but you will need some kind of pressure sensor like the one Jeff and I run in the high side of your A/C system to get an actual pressure reading to the PCM...luckily the GMT400 trucks Jeff and I have already have a port that the sensor works perfectly in, so you might have the same.

I use the LS1 pressure sensor P/N 22664328, its a 3 wire sensor...seeing as how the 2002 silverado uses the same OS as the 2002 fbodies, you might not even need to change the OS or anything...

you *should* be able to install that sensor in the A/C high side, and run 3 wires to the PCM. the sensor cavity A should splice into the C1-60 wire (black, or possibly org/blk) for the low reference, the sensor cavity B should splice into the C1-45 wire (grey) for a 5v reference, and you should add a new wire from cavity C to the PCM at C2-14 (which shouldn't be occupied) for the sensor signal...

I'm thinking that with that you should be able to log the A/C pressure, and the fan settings should respond to you pressure settings in the tune....I'm not 100% sure about the tune though, because my tune is based off the Fbody, not the silverado tune...but with the same OS I don't think it'd be a problem as long as the PCM gets the A/C pressure feedback it would basically be just for the fan control, and logging.

Jeff, I have some schematics if you need them. I don't have the LS1 A/C schematic with me, but if you need it, I can get it to you after I get off work. just let me know.

[Lextech]

Aloicious, I don't think just adding the sensor will do the trick. The tune needs the A/C type parameter set to 2 for the sensor input to function (As far as I know). There is also a type 1 that is on the 03-07 trucks but that is a 1mb PCM and might be a CAN signal based deal---Although I am not sure on that part.
Justin (Aloicious) has had a pressure controlled fan setup on his truck for a long time now--So, I definitely didn't originate this. I have helped a few guys out, but they have been 96-2000 GMT400 truck owners who have upgraded the Black PCM to the 0411 PCM.

Jeff

[aaronr]

Can you guy clarify the C1 and C2 part? How do you know witch one is C1 or C2? (Lextech) wait for your e-mail to verify information above.
Thanks

[Lextech]

C1 is the Blue connector and C2 is the Red connector.

Jeff

[Aloicious]

Aloicious, I don't think just adding the sensor will do the trick. The tune needs the A/C type parameter set to 2 for the sensor input to function (As far as I know). There is also a type 1 that is on the 03-07 trucks but that is a 1mb PCM and might be a CAN signal based deal---Although I am not sure on that part.
Justin (Aloicious) has had a pressure controlled fan setup on his truck for a long time now--So, I definitely didn't originate this. I have helped a few guys out, but they have been 96-2000 GMT400 truck owners who have upgraded the Black PCM to the 0411 PCM.

Jeff

you may be right, but I thought someone over on PPE added the sensor to an Xvan tune (which is switch controlled), and it worked, at least for the fans....so I'm wondering if he can leave his current AC setup alone, and just add the sensor for the fans (assuming the sensor would be recognized, but I'm thinking it might be) instead of trying to change over the AC control to the Fbody style....

its a thought at least..