What valves on gauges should be open and closed during evac?

[Graplr]

Hi all,
Doing an evac of my a/c system.

Here is the manifold gauges I have. (also seen in attached pic)
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649

I hooked the blue hose up to the blue port (low side).
I hooked the red hose up to the red port (high side).
I hooked the yellow hose up to the vacuum pump.

There are 4 valves in total on the gauges.

1 at the high port connection to the car.
1 at the low port connection to the car.
1 high (red) dial on the gauges.
1 low (blue) dial on the gauges.

When I am evacing the system which ones should I have open and which ones should I have closed?

Thanks!
-Ryan

[Bajaman]

AFIK Both. This will allow the evacuation to proceed as quickly as possible. I evacuated for several hours, and checked the vacuum level the next day to verify that there were no leaks.

[Graplr]

Originally Posted by Bajaman

AFIK Both. This will allow the evacuation to proceed as quickly as possible. I evacuated for several hours, and checked the vacuum level the next day to verify that there were no leaks.

Both open or closed? I assume you meant open.

Now I'm wondering whether I have the hoses hooked up correctly or not.

I have the low hose coming off the bottom left screw in and I have the high hose coming of the bottom right of the screw in. They are both connected to the quick connect fittings shown in the pic. Then both quick connect fittings are connected to the a/c system at their respective ports.

Looking at the gauges manual (which doesn't state much btw) it shows the quick connect fittings connected to the side ports on the gauges? Is that where I should have them? I would need additional connectors to get it hooked up to the car then.

[Johnt49]

Open all valves while pumping down. (The port valves are opened by turning clockwise). Leave port valves open, close high & low valves on manifold, turn off vac pump in that order. Observe vacuum on gauges. It should hold steady. If it drops you've got a leak. Technically you only need to open one side, either high or low, to evacuate since it's one looped system, but most techs prefer to open both.

[Johnt49]

Originally Posted by Graplr

Both open or closed? I assume you meant open.

Now I'm wondering whether I have the hoses hooked up correctly or not.

I have the low hose coming off the bottom left screw in and I have the high hose coming of the bottom right of the screw in. They are both connected to the quick connect fittings shown in the pic. Then both quick connect fittings are connected to the a/c system at their respective ports.

Looking at the gauges manual (which doesn't state much btw) it shows the quick connect fittings connected to the side ports on the gauges? Is that where I should have them? I would need additional connectors to get it hooked up to the car then.

You've got it right. The pic of the quick connects attached to the side of the manifold is how they're stored when not in use.
When you're done charging & testing be sure to relieve all pressure from the gauge set. Leaving pressure in will weaken hoses & can affect gauge calibration.

[Graplr]

Originally Posted by Johnt49

You've got it right. The pic of the quick connects attached to the side of the manifold is how they're stored when not in use.
When you're done charging & testing be sure to relieve all pressure from the gauge set. Leaving pressure in will weaken hoses & can affect gauge calibration.

Okay, thanks John. I went out and checked and sure enough the side ones are just holders. There is no holes in them.

Also it appears I had the valves closed at the port. I had them turned counterclockwise. To me that seemed like this would be open. So I turned them fully to the clockwise and it is evacing right now. It pulled down to 29hg pretty quickly. (within a minute)

[Johnt49]

Turning the port valves clockwise depresses the valve in the 134a fitting, just the opposite of how you'd expect a valve to open. I've seen lots of people make this mistake, that's why I mentioned it.
Let it pump down for at least an hour, then check for vac leaks by watching gauges after closing valves & turning pump off. Good luck

[Graplr]

Thanks John.

Now a question about filling with refrigerant. I've already been told the warnings about using cans and switching them out, but I'm going to go ahead with them as many people have had success with them.

Do I screw the can directly to the open screw on the yellow hose fitting without connecting the vacuum pump?

If you look at my first pic there are two fittings where the yellow hose goes. One gets connected to the vacuum pump I assume. Is the other to hook the can up to? If so directly?

[Johnt49]

Originally Posted by Graplr

Thanks John.

Now a question about filling with refrigerant. I've already been told the warnings about using cans and switching them out, but I'm going to go ahead with them as many people have had success with them.

Do I screw the can directly to the open screw on the yellow hose fitting without connecting the vacuum pump?

If you look at my first pic there are two fittings where the yellow hose goes. One gets connected to the vacuum pump I assume. Is the other to hook the can up to? If so directly?

You disconnect the vac pump from the yellow hose. You will need either a universal can tap that wraps around the can puncturing the side, or a 134a can tap that screws to the top of the can. It has a screw which you turn down to puncture the can then turn back to allow the refridgerant to flow through the yellow hose into the manifold & through the blue (low side) hose into the suction side of the system. When you first start to introduce refridgerant do it slowly so you do not rupture the desiccant bag in the drier. You can't just hook the yellow hose to the 134a can as the can must be punctured to let it out. You also want to bleed the air out of the yellow hose by depressing the schrader valve at the top connection on the manifold once you have 134a pressure in it, before letting it flow into the system. Be careful not to get it in your eyes!!