Cautions: The A/C system is under high pressure. Also, while R134a isn't as bad for the environment as the older R12, there is still a heavy fine for venting R134a into the atmosphere. You should never take apart your A/C system without proper training and refrigerant recovery equipment. Wear protective glasses at all times while servicing your A/C. Also, you will be working under or near the car while it is running. Please observe all safety precautions and refer to our disclaimer for carfix_online at the bottom of every email!
With the car running and A/C on Max, pop the hood and listen for or watch the A/C compressor pulley. It has a clutch, so the center of the pulley may spin intermittently. It should start and spin for 30 seconds or longer. If after 90 seconds it never spins, make sure your A/C is turned on. If it spins for just a few seconds, stops, then starts again after a few seconds, it is short cycling. Either of these could be caused by low refrigerant levels. There may be a leak or something more serious at fault.
Interdynamics makes it very conventient for a DYI’er (do-it-yourself) to recharge a R134a system. There quick charge charging gun QCK-2CS,(a video of it can be seen later in this article) and you simply connect the hose to the low-pressure port, screw a can of refrigerant into the Quick Charge, squeeze the trigger to dispense and release to stop. Quick Charge will automatically give you a pressure reading on the built-in gauge. Quick Charge is completely re-usable.
Locate the Low-pressure A/C recharge port of your system. The low-pressure port usually has a blue or black dust cap and is located on the larger diameter metal tubing that runs between the evaporator (in the dashboard) and the compressor. If you can’t find it or your not sure stop here and seek professional help!
With the car off, a rule of thumb is that the pressure should read about the same as the ambient temperature in Fahrenheit. If it's 80 degrees outside, the pressure at this service port should be somewhere around 80 PSI.
Start the car and run the A/C on high with recirculation as shown below. This will make sure that the A/C pump is running as hard as possible. If the A/C compressor isn't running (you can usually hear it), the pressure may read high. If the A/C compressor never starts, or if it's short-cycling, the readings could be off. If the system needs recharging, start adding refrigerant to the system per the instructions that came with the recharge kit. For the Interdynamics charging gun, you simply read the pressure, then momentarily hold the trigger down to add refrigerant. Release the trigger, and check the pressure again.
A few other things to note. There is a high-pressure service port under the hood (covered with a plastic cap, near the radiator). A high pressure gauge hooked up to this port, combined with the low pressure gauge in the recharge kit, can point out a failure with the expansion valve or the compressor. These high-pressure gauges use a different size of connector, and are not usually sold with the "do-it-yourself" style A/C recharge.Note: You can't repair an AC system properly with just a low side gauge. It requires a low side and high side reading to know what is actually going on!
The video below is taken from the “The Two guys” TV show.
charging gun and how it is used.
