Snap-on tools' range of air conditioning (AC) R-134 coolant recharging, evacuation and recovery machines are relatively easy to operate. Because the process of evacuating and recharging R-134 air conditioning coolant involves little more than connecting the proper hoses to the right places, using a Snap-on system isn't dissimilar to using systems produced by other shop tool manufacturers. Air conditioning work on a vehicle should only be done by a certified mechanic.
Open the bonnet of the car on which you will be working and look for the air conditioning compressor and the air conditioning receiver. Between these, you will see the aluminium pipes that transfer the R-134 between the systems. On the air conditioning receiver, you will see a black cap approximately 3/4 inches in diameter. Nearby, on one of the aluminium tubes, you will see a second cap. This is where the lines for the air conditioning machine connect to the car.
Plug the Snap-on air conditioning machine into a grounded wall outlet. You will notice two gauges on the machine.The gauge marked "HP" is used to determine the pressure of the high pressure side of the system and the "LP" gauge shows the pressure in the low pressure side of the system. These are primarily diagnostic gauges used to check that the system charged to the right specifications.
Start the vehicle and run the air conditioning system on high for a few minutes. This will pressurise the vehicle's air conditioning system.
Shut off the car's engine and plug the air conditioning coolant lines from the Snap-on machine into the fittings under the black caps you found on the air conditioning system. The two valves under the caps are different sizes from one another and correspond to the coolant recovery system lines running from the Snap-on system.
Scroll through the Snap-on AC machine's database of vehicles or enter the vehicle's year, make and model by following the instructions on the machine's digital readout. Next, select what you need to do to the vehicle, recharge the AC system or evacuate it for service.
Press the "Start" button on the unit. The Snap-on machine will automatically stop the procedure when it has reached the parameters loaded into its memory for the vehicle being serviced. Once the AC system has been fully charged or evacuated, disconnect the lines leading from the machine to the vehicle.
Read through the instruction manual carefully for the machine before attempting to use it.