What a/c system did the 1988 gmc s15 pickup use? do i need to worry about messing with freon?

step one is test spark at coil first not distributor.(last)
the coil has a HV lug use spark wires HV + plug to test that this is first. if fails the distrib is bad, VR pick up.
s15 jimmy or PU
which engine,
2.5L 151cid L4
2.8L 173cid V6
4.3L 262cid V6 <<<< I will guess this and answer.

try new distributor.
and must be timed,
set engine, to TDC 0-degrees, #1 piston on firing stroke
step1 is that. so new dizzy super easy to put back same. time.

the ICM runs the coil but the ICM has inputs, that must be working
1988 uses what to make ICM work, good pickup coil
The PCM (VCM) runs the 4 wires to the Distributor and ICM in it.
if PCM is bad, or inputs to it are bad, there will be no spark
there is no CKP sensor here ,just CMP and CMP is the pickup coil inside DIZZy and connect to ICM and ICM makes spark. (ign coil)
the PCM I think only does spark timing advance.(called EST)
but no sure me how the 4 wires on PCM to Dizzy work.
a new pickup coil might fix this , (it is CMP named now)
CMP is cam sensor and here it is via cam to main DIZZy shaft to pickup coil)

https://video.search.yahoo.com/search/video?fr=mcafee&ei=UTF-8&p=replace+pick+up+coil+1988+s10+2.8+video&type=E211US1494G0#id=5&vid=7a9ce4130a7206a64f90052ecd85b546&action=click
This is a video on how to do it.

Replace the brake switch. Located under the dash at the brake pedal. $10 part. You can check it with a volt/ohm meter first to make sure.

you have'nt said what you want to replace ?

Change the temperature control sensor to the front if the engine near radiator
1 start the truck let it run till you think it is at normal operating temperature
2 unplug the temp sensor if the idle changes then the sensor is bad

take it right back they should have some kind of warranty

You'll need a bench vice for this. A few sockets help as well. Once you get the shaft off the truck, put a smaller diameter socket on one side and a much larger diameter socket on the other and sandwich in a vice. Compress vice to drive the U-Joint through shaft (smaller socket will drive the one side through the other with the much larger socket). Installation is the reverse of removal.

I don't know that specific vehicle, but if its a hydraulic clutch it sounds like either you have a leak and your clutch fluid is low, or the master or slave cylinder could be bypassing internally. Check the fluid level in your clutch master cylinder. If its low, you should top it off with brake fluid and will probably have to bleed the system. Also look for leaks. You can probably find info or a video online of how to bleed the system. Its a bit hard to explain without illustrations or pictures. Not really very difficult to perform. Good luck.

Hello cman0906: My name is Roger and I will answer your question. The fire order is 1 5 6 4 3 2. See picture. Please rate the answer you recieved. This way we know your answer was correct. Should you need further halp please just ask. Thank You for using Fix Ya. Roger

have you tested for voltage at the compressor?

It may have a bad AC clutch, or a wire is split somewhere in the harness. check for appropriate voltage at the compressor.

you mayyy need a new compressor if you infact have voltage to it