98 old body style truck, was a 4.3 V6. Now it's a 5.3 and I made my own a/c relocation using an R4 compressor. I plugged in all of the factory truck wiring and could never get it to enable the compressor. Checking the original pcm connections, I decided they weren't all there and decided to wire it up myself. Here's where I am now, all wired standalone.

Wire from the interior button to positive side of relay
Wire from stock switch on the accumulator providing ground to relay
Relay provides positive power to the compressor
That way, without either one the system is off.

Apparently that switch on the accumulator doesn't make it cycle, because it just stays on all the time. The switch is constantly providing a ground so it just stays on. If I unplug that switch, it does turn off. stays running at 22psi and never changes. Also doesn't get cold, lol.

What am I doing wrong?

 

Maybe the safety switch needs to be bypassed?

 

There is no safety switch. I only have the stock switch on the accumulator hooked up.

I have been told that I may need to swap to a different style of switch, like an 88 chevy or so, as they were a 1 switch system and the stock 98 switch might not simply open/close since it was a signal to the pcm. If anyone has info on that, it would be much appreciated as well.

 

I don't know '98, but I think the AC is the same as my '99, and I think trucks work the same way too. There is no "pressure switch" on my '99. There's an A/C Refrigerant Pressure Sensor that tell's the PCM what the high side pressure is. The PCM will disable it's output for the compressor relay if the high side pressure drops below 30psi or goes above 410psi, basically the same as an old fashioned binary switch would do.

 

If the computer was reflashed to an LS1 engine(F-Body), then the A/C system requires a trinary(3-prong) F-Body pressure switch added to the high pressure line, for the system to cycle properly. Then you just need to know the proper pin-outs to wire it up.

 

I wired it all standalone with an R4 compressor, there is no computer or anything.

I swapped out the switch and it works great

 

Got a part number for the new accumalator switch that you used? Thanks

 

ITS NOT A TRINARY PRESSURE SWITCH. It's a pressure sensor, puts out 0 to 5V in relation to the high side pressure.

 

3041336 is the old style one that will work.

I tried the newest version and part number for a stock replacement for the 98 original and it works as well. Only the stocker gave problems. The newest part number for the stock switch is 52466358