I have plans to wire up the a/c pressure sensor this weekend. 02 0S has settings for it so might work after get pluged in.

 

Keep us posted, this peaked my interest.

 

i have an 03 pcm that was dbc but no electric fans. it was a 03 2500 van

 

Atomic,
I was looking through a 2004 chevy truck tune and looks like per this table i would be able turn off the electronic throttle if i understanding this table right.

 

You can run DBW or DBC on 1999 to 2010. This depends on the PCM service number and if it's newers than 2006 it need too have a PCM not the ECM.

To have the AC pressure turn on the secondary fan you will need to install the AC pressure switch. GM used E fans with AC and no pressure sensor from the factory on some LS based PCM's (0411). This is also a Cycling type AC compressor like the one used on the trucks

 

Ok, dumb question. I swapped my PCM long ago when I pulled the clutch fan, and installed the e fans. The PCM I went from was an '02 Silverado Ls to a Tahoe. I never had an issue since. I have the same PCM on the 6.0.

Wouldn't it be easier to swap the tune to a Tahoe PCM, than having to dig through tables and threads?

 

I found out the same thing when I installed my fans. 99-02 have a high pressure switch that will automatically switch it over to recirculate to help bring the high side pressure back down but there is no real time high side pressure input to the PCM like on the 03+ trucks.

I used 05+ 34 inch fans and last summer it got to 116 degrees a few times and a lot of days were 110 and it would idle in direct sun with the AC on blowing 38 degree air with the fans only running on low. Even on low speed the fans move WAY more air then the fan clutch setup could ever dream about with an engine idling at 550 rpms. The other nice thing is that with the fans on low they are virtually silent and only pull about 5 amps so the alternator isn't getting its guts pulled out. I'm happy with how it turned out. It made a truck out of it after getting that power robbing fan clutch off there. Between the super hot air and the fan clutch I bet it would loose 50 hp and a ton of torque when taking off after idling through a long stop light. Now it doesn't seem to know the difference.

 

So are you saying the 02's have a high pressure switch from factory, that is different from the pressure sensor that the OP is looking to add? I am very interested in this as well. I burnt up 3 relays last summer myself, and am looking to fix this issue before the summer.

 

ill have to figure out how mine is setup.. but im still on the same $4 relays from 5 years ago. my fan 1 is on when my AC is requested. it doesnt cycle with the compressor (thats really aggravating to me) . when i get up to speed my fans go off.

 

99-02s have an A/C high pressure recirculation switch. It is an input to the PCM that when the high side pressure is above 325 psi makes the PCM turn the A/C system over to recirculate regardless of the selected setting.

This is what I've been using for the last year and its worked great.