Controlling rad fans with A/C

[ostrich]

What are you using to trigger the fans right now?

 

[Winkernod]

Using the PCM with the 98 Camaro 3 wire coolant sender.

 

[ostrich]

What pin from the PCM are you using right now to turn on the fans? I'm thinking if you use Pin#42 it will -ve trip your relay(s) (if you have the 2 Intrepid fans separate), when the coolant temp calls for it and then an AC request. So 1 relay/fan, Pin #42 split for the relays. Unless you want fans to come on separately?

 

[Winkernod]

I am already using blue pin 42 for my 1st fan set for 190 and then if temp gets to 220 second fan red pin 33 and they go to ground I had to refresh my self on how this was setup. I had misread what pin 42 was. Some days I am easily confused. As with most pins they go to ground, not powered. I had to go back to LT1swap.com an they say you need to add a relay for the A/C if you what the fan to come on with the compressor

In this diagram "to fan relay control(-)" is the same wire from pin 42

 

[ostrich]

There are a few different ways to wire it up, conflicting info on the web as well. Not sure if you are using your Intrepid fans in low& high mode? If so the relays and wiring get a little more confusing. I have the Intrepid fans in my 3rd gen Camaro (running a 2002 Camaro 411 PCM, no AC) and I use Pin#42-low speed, and Pin#33-high speed for the 2 relays. Reading things Pin#42 should also control low speed for AC requests. Planning on doing the same for my 85MCSS with Intrepid fans w/AC. Check this link out, there is some HPT programming, but should work fine.

Can a 2002 truck PCM and harness support hi and low speed electric fans? - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - Can a 2002 truck PCM and harness support hi and low speed electric fans? - I was looking at some schematics for a 2002 truck, and noticed that there were no provisions for electric fans. Can the 2002 and older truck PCM + harness be setup to run hi speed and low speed fans...

ls1tech.com

 

[Winkernod]

I have the fans running separately so when PCM calls for low only one fan runs when the PCM calls for more cooling the second fan kicks in. Something I was thinking was to have the second fan run during the compressor cycle and then if the temp climbs to 190 then the first fan would join in

 

[Supercharged111]

I looked into Pin#42 from my Camaro schematics and it is the same Fan#1 control as a truck 411 PCM, so it should work.
The PCM will complete the ground path for cooling fan relay #1 under any of the following conditions:

• When engine coolant temperature exceeds 105°C (221°F).
• When A/C is requested and ambient temperature is greater than 10°C (50°F).
• When A/C refrigerant pressure is greater than 190 psi (2 volts).

The factory fan cal is garbage WRT coolant alone, my 2nd fan on my Corvette wouldn't come on until like 235! That and the skip shift were among the first thins that I changed. The AC fan controls seem to work well though.

 

[ostrich]

I have the fans running separately so when PCM calls for low only one fan runs when the PCM calls for more cooling the second fan kicks in. Something I was thinking was to have the second fan run during the compressor cycle and then if the temp climbs to 190 then the first fan would join in

Should be able to program that with HPT pretty easy.

 

[Injectedcutty]

I have the fans running separately so when PCM calls for low only one fan runs when the PCM calls for more cooling the second fan kicks in. Something I was thinking was to have the second fan run during the compressor cycle and then if the temp climbs to 190 then the first fan would join in

Let me get to the house and I'll snap a pic of how my fans are tuned in HPT. I'm running aftermarket fans, but controlled by the ECM. Mine are only on/off though and not low/high, and I'm not running AC.

 

[Injectedcutty]

My current tune....