What exact suction press charge 134a - 1994 GMC Jimmy

By pass clutch signal by appling +12vdc to A/C clutch directly - check for proper suction side pressure with A/C gauge connected to suction side of compressor - if pressure is low clutch will not be energized do to low pressure cutout switch. Add freon or 134A to bring up suction side pressure. https://www.6ya.com/callphilipforhelp

Look up videos for servicing a/c system on full size Gm trucks on YouTube. You should find some of these videos helpful. Good luck.

AC clutch has to be energized for the compressor to turn and cool. Check out the thermostat as well as the low pressure cut off switch, relays for proper operation.

If you connect the 12 volts to the hot side of the clutch it should engage - if so that indicates that the issue is caused by some electrical item in line with the circuit that powers the clutch.

Sounds like the low pressure switch is cycling the compressor off. This normaly indicates a low charge that is a result of a leak in the system. You will need to have the leak located and repaired then the system evacuated and recharged with the correct amount or refrigerant. 134A works best with the exact charge for the system.

to charge car uses 134a freon, you get a can at parts store, can has a hose and gauge already on it. hose end only fits your low side suction port ,it slides on and snaps /holds in place,do as can instructions say, DONT OVER FILL 134A SYSTEM IS WORSE THEN UNDERCHARGE AND YOULL PAY ALOT MORE FOR OVERCHARGE TO GET REPAIRED THEN A JUST RECHARGE SERVICE.MOST OIL CHANGE SERVICE OFFER A/C RECHARGING,Me id go to someone that has ASE tech certified in AC

It will have two valves. One Suction and one discharge. Follow the tubing from the compressor out, one will run to the front of the car (smaller of the two lines) this is the discharge line (high Pressure) along this line will be a valve before the condenser coil. Follow the large line from the compressor back to the firewall area and along this line ( this is the low pressure or suction side) you will find the suction valve. This valve is the one most folks use to check the system pressure. Hope this helps.

if u adding through a can from a parts store, u need to have the system evacuated 1st to make sure u dont have any in there before u add the incorrect amount and lock up the system.

it's the smaller of the two ports, low pressure, and no 134a will work, unless you have r12 in the system. you can get a retrofit kit at the parts store

The charge level is too low? How do you know? Too much freon will not cool good just as too low makes the system friezze up. The port is on the side or the reciever dryer behind the strut tower passerger front side near firewall. Days of yore r12 systems the more the better, not so with 134A. If you have to ask this question hire the work done as mistakes will cost way more than the money you'll save doing it yourself

Are you on the suction line? Large fitting. Shake the can and warm it up. Do not overcharge. Make sure the A/C compressor is running.