Hello everybody,

Do I have to empty the A/C system before I remove the A/C cycling switch and screw a new one on the suction accumulator-drier...? If I need to purge the A/C system, can I do it in my driveway..? It's B4000, 2002, standard 4x4.

Thank you for your advices!!

 

yes you will have to empty the system. It works off pressure so if you just unscrew it it will blow freon in your face and make for a really bad day. When you put the new one on, you will have to vacuum the system back down to remove any moisture in the system and to create space and give it the ability to pull the charge into the system.

 

also make sure you install it with a new o-ring too

 

How do you purge / vaccum the A/C system?

 

you are going to need a gauge set and a vacuum pump. You can get a cheap pump that runs off your air compressor for at Harbor Freight. The gauges are the expensive part though.
But here is the vacuum procedures:
Attach a/c manifold gauges to the vehicle. Make sure you attach the correct hose to the proper service port (R-134 systems have different size ports for the high and low sides and the gauges can only hook up one way on them). Attach center hose (Yellow) on the gauge manifold set to an a/c vacuum pump. Open both of the dials on you’re a/c manifold gauge set. This will allow the system to be evacuated through both the low and hide side of the system. Turn your approved vacuum pump on starting the evacuation process. 30 minutes usually will be enough time.
When system has achieved a state of 29.9 hg’s of vacuum close both dials on the a/c gauge set. At this point wait 5 to 10 minutes letting the vacuum boil off any moisture trapped in the refrigerant oil. This is also a good time to watch and see if vacuum has returned to a zero state. If it does lose vacuum (1 hg per 1000 ft above sea level is normal) you need to check for leaks in the system. Assuming the system is holding a vacuum after letting the moisture boil off.