ac service port valve

[f1shermun]

I had some issues figuring out how to operate the valves.

all the way in = closes off that line and opens the service port to the compressor
all the way out= opens the compressor to the line (normal position)

half way open= opens the system for service.

It was a little tricky figuring it out without a manual. it is simple enough as long as you close both valves all the way in before you remove the caps and hook up the guages. I spoke to an AC guru who said that I could use the trucks compressor to pull a vacuum on the system. Has any one on here ever tried that? I have used my Harbor freight venturi style vacuum and it has worked fine so far.

[fordman]

i have heard of people using the compressor to fill air tanks on truck for emergency air to air up a tire or what ever.

[70_F100]

It was a little tricky figuring it out without a manual. it is simple enough as long as you close both valves all the way in before you remove the caps and hook up the guages.

The gauges should be connected with the valves screwed all the way OUT. That closes the service port. If you screw them all the way IN, that opens the path from the service port to the compressor. If there's any refrigerant in the system, there will be some in the compressor that will escape.

I spoke to an AC guru who said that I could use the trucks compressor to pull a vacuum on the system. Has any one on here ever tried that? I have used my Harbor freight venturi style vacuum and it has worked fine so far.

Yes, you can use the compressor to pull a vacuum. However, all that will do is to bring the system into a state of vacuum. The purpose of evacuating (pulling a vacuum) a system is to lower atmospheric pressure to a point that any moisture in the system will boil at ambient temperature and the water vapor will be pulled out by the vacuum pump (approximately 28 in Hg, varies with elevation and barometric pressure). This requires about 45 minutes to an hour to completely rid the system of any moisture. Using the compressor as a vacuum pump will not accomplish this.