new install charging problem

[msrichmond]

In your diagram, the condenser is inverted.

High-pressure refrigerant gas from the compressor enters at the TOP of the condenser, condenses, and travels to the outlet at the BOTTOM, exiting as a high-pressure liquid. The liquid refrigerant then flows from the bottom of the condenser to the R/D and on to the TXV, where it changes from a high-pressure liquid to a low-pressure liquid.

The low-pressure refrigerant gas (and sometimes a mixture of gas and liquid on systems having an OT and accumulator) exiting the evaporator is normally cool to cold.

I had a sinking feeling that I was going to be pulling my radiator out and fabricating new hoses. Fortunately, I checked the car again and it is my diagram that was wrong, not my install!

[JohnHere]

That's better.

Glad the installation was correct and just the diagram was wrong.

[msrichmond]

OK. Verified all the hose connections. Both red and blue hoses connected, schrader valves opened by twisting clockwise. Only the blue side open the manifold gauge set. Reading 65PSI on the blue side. Zero on the red side.

Verified with voltage checks that I'm getting the signal out of the evaporator to the trinary switch. Compressor does not come on.

With the engine off, I bypassed the connections to the trinary switch and verified a clunk from compressor indicating that the evaporator could turn on the compressor were it not for the trinary switch.

I have so little volume of R134A in the system, would it be OK to run the compressor to see if I can get some more in?

[msrichmond]

I don't remember, but if my blue side valve was closed when it should have been open then I never really pulled a vacuum. I'm going to start over.

[msrichmond]

I did the whole process over. Pulled a vacuum purged the yellow line, but one thing I noticed was nothing cold ever came out; the can did get lighter though.

Anyway, 50 PSI back in on the blue gauge. I tried cycling the compressor and nothing changed. Zero on the red gauge.

Something must be plugged. Everything is new, so very discouraging.

[JohnHere]

Try this: Momentarily depress the stem of the Schrader valve in the high-side service port with a small screwdriver or other suitable tool and see whether anything hisses out. If so, something is wrong with the connection of the MGS to the service port, the Schrader valve itself is bad, or the high-side gauge is defective.

You have a static pressure of 65 PSI on the low side. You should be seeing approximately the same static pressure on the high side if everything is working right.

[JohnHere]

I don't remember, but if my blue side valve was closed when it should have been open then I never really pulled a vacuum. I'm going to start over.

Whenever evacuating a system, be sure to fully open both the low-side (blue) and high-side (red) handwheels on your Manifold Gauge Set. It's only when charging a system that you need to be 100-percent certain to keep the high-side handwheel closed. The reason is personal safety.

Consider that the high side typically has pressures of 200 PSI or greater. A refrigerant can has far less pressure than that. Opening the high-side handwheel while charging will cause the much higher high-side pressure to back up into the can, a pressure that the can was not designed to withstand. The result is usually an exploding can. If you happen to be holding onto the can when it explodes, well, no need to elaborate further.

[Cusser]

Whenever evacuating a system, be sure to fully open both the low-side (blue) and high-side (red) handwheels on your Manifold Gauge Set. It's only when charging a system that you need to be 100-percent certain to keep the high-side handwheel closed. The reason is personal safety.

Consider that the high side typically has pressures of 200 PSI or greater. A refrigerant can has far less pressure than that. Opening the high-side handwheel while charging will cause the much higher high-side pressure to back up into the can, a pressure that the can was not designed to withstand. The result is usually an exploding can. If you happen to be holding onto the can when it explodes, well, no need to elaborate further.
[/quote]

THIS

[msrichmond]

Try this: Momentarily depress the stem of the Schrader valve in the high-side service port with a small screwdriver or other suitable tool and see whether anything hisses out. If so, something is wrong with the connection of the MGS to the service port, the Schrader valve itself is bad, or the high-side gauge is defective.

You have a static pressure of 65 PSI on the low side. You should be seeing approximately the same static pressure on the high side if everything is working right.

Nothing hisses out when I do this test. And the gauge on the high side pegged below zero when I ran the vacuum pump. Looking in the direction of flow, there is a lot in the way that could be blocked. But looking backwards there is just the expansion valve. So If I loosen the #6 connection to the expansion valve and nothing comes out then the problem is the expansion valve, right?

I have the can tap attached but turned fully counter clockwise to keep new refrigerant from entering at this point. Blue wheel on MFG is still open. Red hose disconnected from service port.

[JohnHere]

Nothing hisses out when I do this test. And the gauge on the high side pegged below zero when I ran the vacuum pump.

We now have concrete evidence that your MGS on both the HS and LS are accessing the system and that the HS gauge isn't faulty.

I've dealt with a problem like this before, but I've never seen one side of the system completely obstructed like this. We've exhausted all other possibilities except for the HS being blocked someplace.

Looking in the direction of flow, there is a lot in the way that could be blocked.

Right...you're getting refrigerant into the LS through the MGS LS service-port connection and building pressure in the LS, but you're getting neither refrigerant nor pressure into the HS based on your "zero" pressure reading on the HS. I'm guessing that refrigerant can't flow backwards through the TXV (although I've never experimented with this scenario). The next potential stoppage point is primarily the compressor, followed secondarily by the condenser, R/D, and TXV.

If, as the diagram shows, your HS service port is right after the compressor's outlet connection, then by default, something inside the compressor must be stopping any pressure from building in the HS, possibly a reed valve being stuck shut, or something else.

Is your compressor a variable-displacement or fixed-displacement type? I don't remember your mentioning that previously.

So If I loosen the #6 connection to the expansion valve and nothing comes out then the problem is the expansion valve, right?

Not really. It still doesn't explain why there's no pressure on the HS, so the problem must be upstream from there.

I have the can tap attached but turned fully counter clockwise to keep new refrigerant from entering at this point. Blue wheel on MFG is still open. Red hose disconnected from service port.

If you have the can tap's valve turned fully counterclockwise, then it's fully open. But if the handwheel on the blue side of the MGS is open but the service port adapter's thumbwheel is closed (if your adapters actually have thumbwheels; some don't), then refrigerant won't flow into the LS unless you have adapters without thumbwheels, in which case they're always open whenever they're connected to the service ports.

If your red hose is disconnected from the service port, then nothing will register on the HS gauge whether the HS handwheel is open or closed.