E fan control for ac with 2007 van computer

[Kman1073]

I have a 05 lm7 controlled by a 07 p59 van computer to use the 12v ac request instead of the serial request from the truck computer. My fans currently work correctly without ac on, but I have the manually overridden to come on high if the ac is on. I would like to be able to control the fans through the pcm for ac, but not sure if the pins on the van computer are active to receive data from the pressure sensor. Does anyone know if this will work and how to set it up in the tune once the sensor is installed?

[bk2life]

I would like to be able to control the fans through the pcm

is this a swap?
might be easier to install a trinary switch

[Kman1073]

Yes, it's a swap. Just wanted to try and use the factory stuff instead of a trinary if possible

[Alvin]

You would need the A/C pressure swtich.

I have a A/C bump circuit which bumps the fans up to the next speed if the A/C comes on. great for swaps.

[SkinnyG]

I explored this for my '07 P59 van PCM and came up empty. Not saying there is no solution, I just never found anything that worked.

I used a trinary switch that came with my home-built AC component parts, and just ran a second relay to control the fan through the trinary, independent of the PCM. PCM still controls the fan for engine temp through a relay, my AC uses a second relay. Same fan. I don't think the fan turns off "at speed" though, which I would like.

Also a swap.

[Kman1073]

explored this for my '07 P59 van PCM and came up empty. Not saying there is no solution, I just never found anything that worked.
What all did you try to make work?

[Fast4.7]

Enable the AC pressure DTC to "No Mil" from "No Error Reported" and the pressure sensor is enabled by the PCM. I have tuned an actual P59 van with electric fans. Just added a pressure sensor to the OE discharge hose.

[Kman1073]

Thanks fast, I appreciate the knowledge.

[Fast4.7]

Thanks fast, I appreciate the knowledge.

No problem. I think the van I did the change on was either an 04 or 05 but the 07 PCM code should have the code in it as the vans use the same OS as the trucks for a given year model.

I set set the AC request low fan coolant minimum to like 30F on everything I tune. The fans will atleast run on low with ac request as long as the vehicle is under the MPH shut-off setting. I find it stops the fans from constantly cycling with the compressor which tends to burn up the relay contacts over time.

[Fast4.7]

I figured out the AC pressure sensor DTC setting doing the reverse. Using a tune for a vehicle that had a pressure sensor and efans from the factory in an older vehicle that needed analog cycling and had a clutch fan. Without the pressure sensor the PCM would set a DTC for the sensor and shut the compressor off after ~10 seconds.