Ricardo

I did a 1996 LT1 A4 engine swap into my 1989 C1500 Truck. Everything is working perfectly with the exception of the A/C.
I need to know if there is a way to command the PCM to turn on the cooling fans in order to keep the A/C condenser cool when the compressor is running.
I could do it with a relay wired to the A/C compressor clutch feeding the fan motors directly but wanted to hear other ideas first.

Here is a picture of the LT1 sitting in there:



And here from another angle:

blown94

Nice bro, ive been slowly getting around to this exact same project as well. You got her fired up and everything huh? How hard was the wiring as far as getting her started? Pm me if ya want, any and all details will be greatly appreciated. Ive been through the LT1 harness numerous times, but not the 1500. How many splices did you need to get her fired up? I see you dont have f-body brackets though, so you didn't have to grind the frame to fit the stock a/c compressor. Are those the vette brackets? Hit me up, very interested in following this build. Subscribing....

Ricardo

I installed the alternator high on the drivers side with a set of home made brackets and re-routed the accesory belt drive:



The original Truck A/C compressor was mounted on the LT1 alternator location.
I used an alternator pulley with a ball bearing as an idler to avoid hitting the truck frame on the pass side.
I also removed the connection on the water pump that was originally used for the oil cooler and plugged it.

shoebox

The LT1 PCM already has a function to turn fans on with the a/c. All you need to do is hook your relay(s) to the signal wire(s) from the PCM. You can find schematics on my Tech Page.

Ricardo

Rob:
I have the A/C controls from the truck running the A/C system. I wired the the A/C compressor hot line to the A/C clutch status input on the PCM (connector B21). This connection does run one of the cooling fans at high speed but it will also set two codes on the PCM and the fan will not stop even if the A/C is turned off. You have to shut down the engine and then the fans will run normally afterwards.

wdricker

Ricardo: Hello I'm new to this forum, I'm especially interested in your project. I also have a 1989 c-1500 that i just lost the motor in it yesterday. I already have a 1995 LT1 out of a Buick Roadmaster, I purchased this motor 2 years ago for another project that never got started. This 89 c-1500 is now going to recieve a upgrade. So hoping we can help each other out. Hope this post isn't so old you don't look at it anymore! wdricker

Ricardo

Well, unfortunately I sold the truck a couple of weeks ago, but I did take a lot of pictures of the whole process and also kept written records and schematics of the electrical. I will gladly help if i can.
there is some information on the Street & Performance website regarding an LT4 swap into an '84 truck that helped some. They did it the most elegant way, but there is a lot of usefull information there you can use or discard.

The engine transmission combo drops right in once you figure how to go about the AC compressor on the F-Body. It will hit the truck frame. I dont know where the ac compressor is located on the Buick roadmaster. If it hits the frame you can also use a complete LT1-vette accessory drive.

For fuel supply you will have to replace the pump in the tank with a vette pump in order to get the 45 psi needed for the LT1.

Shoot me with any questions. I will try to answer and/or send you the pictures.

bentrod

Sorry to bring this back from the dead...but hey Ricardo those brackets look great enough that the thread should be resurrected.

Anyway, could you please share some more pictures of the idler pulley + custom bracket on the left side? Also, did you have to shave the mount lug on the bottom to clear the frame? Better yet, any .dxf or Gcode available?

My truck is receiving this upgrade also. It's 2wd and because of that, I think the motor mounts move the engine even farther forward. The motor barely fits in with the AC removed, the accessory mount scrapes the frame on the way down.