ClusterTruck; because that’s what it is

[clay68c10]

I needed to mount my LS fuse box, and wanted it to look factory-ish. I thought about closing in the bottom fully, but decided keeping it open fit the vibe better and gives some access.

[clay68c10]

Now for some AC parts. My harness came from the deliverance dude and looked pretty decent. Seems it had spent some time outside tho. The relay had no continuity when I tested it.
Time for a relay upgrade since these just work and I have lots of them.

[clay68c10]

I wanted to add a heater core shut off valve but wanted to maintain the LS bypass. Some research led me to this setup. It fits well and should work.
The hard line and some T’s are from the 4wd actuator circuit off a 2013ish 5.4 Expedition. Plenty of those in the junkyard.
I used a little heat from a lighter to get the bends in the vacuum line. It’s teed into the same circuit that actuates the cowl flaps for recirc.

[clay68c10]

Since I’m using an 04 DBW PCM I had to do some work to get the computer to run the AC compressor.
My original PCM part number is set up to take in a CAN data signal from the HVAC module for the compressor on command. Most blue/green PCMs are this way, but there are a couple other part number blue/greens that can accept a 12v signal. The LT1swap site gives you this info.
I found one of the compatible ones on the Bay and will use it instead of my original. It was $30.
To make this work electrically, you need to move the AC input wire on the PCM from C1 #59 to C2 #17.
Then I needed a 12v trigger input.
The C10 system just used the flap box switch to energize the compressor clutch continuously. The 12v source there is the yellow wire and the output is green.
The LS side of things uses the low pressure switch on the accumulator to signal the HVAC module to cycle the clutch.
To incorporate both, I wired the low pressure switch on the accumulator in series with the flap box switch and sent this to the PCM to tell it to cycle the compressor.

[clay68c10]

So, one might ask what’s the benefit of having the PCM run the compressor?

Rapid idle speed control adjustment when the clutch cycles
Fan control to keep the hi side pressure down
WOT compressor cut off
Clutch disengagement when starting


I re-routed the pressure switch wiring from the back of the engine to the front by the MAF. It seems more tidy to me.

[loudchevy]

Originally Posted by clay68c10

So, one might ask what’s the benefit of having the PCM run the compressor?

Rapid idle speed control adjustment when the clutch cycles
Fan control to keep the hi side pressure down
WOT compressor cut off
Clutch disengagement when starting

These seem like good reasons to me!

[clay68c10]

Originally Posted by loudchevy

These seem like good reasons to me!

Yeah, hopefully it all works. Since they're factory functions it should.

[raggedjim]

Nice work Clay. I have a 5.3 LS in the storage part of my shop waiting for a place to go...