02 ECM, electric fans, adding ac controls

[Hotwire]

Hey guys,

short story, 5.3 in s10 blazer, ls1 e-fans, wired up like camaro, low speed = series, high speed = parallel. Works great w/ temps I've programmed.

Just added a/c and I cannot figure out how to get the fans to turn on with a/c. Not sure if I'm missing a setting in hp tuners or what.

The ECM came out of an 02 Yukon, red/blue connectors. I know the 02 model didn't have e-fan option.

Can I get the ecm to control the fans w/ ac or am I going to have to tap the a/c request line to get the fans to run w/ ac?

Thanks!

[6speedblazer]

jeff i just tested my fans after the rewire and it did not work. i swapped it around so the low speed was the "always on" and it kind of worked but i got some weird cycling of the fans and i didnt get my MPH cutoff like i wanted.

still need to figure this out as i dont want to open the system to run a trinary switch, but i dont want the fans running on the highway with the AC on.

I need to mess with some settings, but i might be able to get this to work.

[Hotwire]

Thanks Mark, appreciate the info.

I've got the low speed fans to kick on w/ the a/c but nothing from the high speed fans. Thinking I'm just going to reduce the fan temp cut on so they will come in faster and pull air through the condenser. Seems the easiest way to go at this point. I do have a pressure sensor wired up to the high side and can see the voltage changes from it, but since it's an 2002 model 0411 ecm, not sure I can do anything with that info.

Also, does anyone have a chart that correlates the high side pressure to the voltage from the sensor?

Thanks,
Jeff

[IvanDeslayer]

Jeff
Did you have it wired for the fans?
Pin 42 dark/green circuit 335 low speed fan relay control Blue connector
Pin 33 dark/blue circuit 473 high speed fan relay control Red connector
If you enable it for 2 fans make sure when you go into A/C settings that it's set for Fan#2 otherwise it's trying to control the recirc door and won't come on till the high side pressure reaches 350lbs I think.

[Hotwire]

Thanks for the reply IvanDeslayer, the fans have been operating for quite a while now like factory with no issues, fan 1 / 2 are wired correctly and do a good job of keeping my mish mash running cool.

The issue is now finally getting a/c plumbed up and running, didn't realize I was going to have a problem getting the fans to work with it.

I do have the fans set to Fan#2.

I set the ac fan enable temp to 70 degrees. That way as soon as I turn the a/c on, fan 1 enables. BUT, if my ecm isn't seeing the high pressure sensor, I have no way of getting fan 2 to kick on.

To save from extra wiring, adding diodes, and relays, I set the engine fan temps lower than normal so that when the a/c condenser gets warmed up and heats up the engine bay it kicks fan 2 on. It's a band aid but hopefully will work.

I just didn't know if there's a way to enable fan 2 w/ a/c settings, don't want to blow the expensive compressor or custom lines..

*EDIT* Here's how I wired in the high pressure sensor:

A - PPL - Low Reference - Blue connector pin 23 (EGR Solenoid Ground)
B - GRY - 5V Reference - Blue connector pin 48 (EGR 5V Reference)
C - RED - Pressure Sensor Signal - Red connector pin 14 (not used in 2002 ECM)

[IvanDeslayer]

Oh aha I see what you're doing. Yeah I don't think there is a way. Hopefully someone smarter comes along and give a definitive answer. Sorry.