A/C Wiring with 5.3 Swap questions!
 

I'm going to be adding vintage air to my LSx swap in my '70 C10 and I'm planning on running the a/c wiring through the computer so that the e-fans and idle can be controlled by it. The engine is a 2002, drive by cable, 5.3. I read on some posts that only two wires are needed at the computer: the a/c request wire and the a/c relay control output, however when I look at the pinouts, I'm seeing two additional wires both coming from a/c pressure sensors. I'm planning on running the VA's safety switch to make sure I don't burn up the compressor, but do I still need the pressure signals at the PCM for it to function properly?

Re: A/C Wiring with 5.3 Swap questions!
 

The two sensors are the high and low pressure cut outs, you need them for the A/C to work right. However just hooking up the A/C request should bump the idle but not sure about the fans because 2002 trucks don't have electric fans, If you're using the pin out that originally went to a recirc door your PCM can be tuned to turn the fans on with the coolant temp sensor, but since the PCM doesn't know what the A/C pressures actually are so it probably won't work with the fans. The high and low pressure switches on an '02 are just on/off switches, so you could use what ever your Vintage Air set up came with.

Re: A/C Wiring with 5.3 Swap questions!
 

Im putting a 5.3 in a 67 using the stock 5.3 comoressor. Problem is wiring harness dosent have the wiring to controll the idle up when a/c is on. Is this gonna be a problem?

Re: A/C Wiring with 5.3 Swap questions!
 

The AC pressure sensor will protect the compressor by cutting it off if the high side pressure is too high or too low. The pressure sensor also allows the ECM to control the fans so that they only run when necessary to reduce the high side pressure. At least that is the way it works on my LS2. You can get by without the idle bump.

TR

Re: A/C Wiring with 5.3 Swap questions!
 

The PCM will bump up the idle when it sees a load on the engine from the compressor. There may be a slight delay, but its not really noticeable.
Posted via Mobile Device

Re: A/C Wiring with 5.3 Swap questions!
 

I guess i can use thr pressure sensor to controll a relay to turn the fans on. Where did you get your compressor lines block? I read dock's no longer has them.

Re: A/C Wiring with 5.3 Swap questions!
 

The ECM should be controlling the fans for coolant temp anyway. If so you don't have to do anything additional.

I got my block before Doc's quit selling them. Only a few dollars at the time. My build thread has the details.

TR

Re: A/C Wiring with 5.3 Swap questions!
 

I used 2 switches. 2005 5.3, stock 5.3 compressor. The low pressure cutout and the 2005 cycling Switch that controls the fans via the computer. My power ac on goes through both. Fan comes on when ac turned on, second fan cycles with pressure. No compressor cutout yet for when I floor it. Coming soon with gas pedal normal on switch, off when floored.
Posted via Mobile Device

Re: A/C Wiring with 5.3 Swap questions!
 

Docs has dealers that have them, they just no longer sell to general public. Find a dealer on their webste. Jim
Posted via Mobile Device

Re: A/C Wiring with 5.3 Swap questions!
 

Vintage Air sells Trinary switches (Optional on kits) that can turn on a fan via relay at 250 PSI of head pressure, Mounts directly to the drier.

Use a New Sanden compressor from Vintage Air, If not...ANY A/C performance problem will be on you.....NOT Vintage air.