new install charging problem

[msrichmond]

New install, Sanden 5072 compressor, brand-name receiver/dryer, trinary switch and evaporator unit. Small generic parallel flow condenser. Two electric fans.

This is my first AC project.

I was only able to get a few ounces (less than one 12 oz can) of refrigerant into the 'blue' port before the manifold blue gauge registered 85PSI which is where it sits now. The compressor has never come on. Red valve is closed and shows zero pressure. Everything held vacuum overnight.

I have verified +12V coming out of the evaporator when the thermostat is set to 'cool' and also 0v coming out of the trinary switch. I have two fans through relays that are wired for the trinary switch and the radiator temp switch to trigger. The temp switch does do that, the trinary switch does not because the compressor isn't coming on to build pressure on the high side.

[JohnHere]

The refrigerant isn't making it to and through the high side due to a complete blockage someplace.

[msrichmond]

The refrigerant isn't making it to and through the high side due to a complete blockage someplace.

The only thing I bought 'cheap' is the condenser, and it would be hard for that to be completely blocked.

The name brand compressor shipped with oil, which per the supplier I did not remove, although I saw advice on another thread that I should have. The compressor turns with a socket on the center.

I can imagine that maybe I left a nylon plug in some component like maybe the receiver/dryer? Is it possible for the new expansion valve to be plugged?

Just to be clear, I am supposed to leave the red valve closed, right?

There isn't much in there (a few ounces) so maybe I should loosen connections until I see something escaping?

[JohnHere]

Anything is possible with pressure readings of zero on the high side and 85 PSI on the low side. But let's start with the simple stuff.

Are you sure you have the low-side adapter's thumbwheel fully open (turned fully CLOCKWISE) so that it's also opening the Schrader valve inside the service port adapter and not just charging into the hoses on the Manifold Gauge Set?

Do you have the hoses attached correctly to your MGS? Some hoses might not permit flow if installed incorrectly.

Is the R/D installed in the correct orientation? There's usually an arrow on it indicating the direction-of-flow, which should be from the condenser toward the TXV.

You're right, the high-side red handwheel on the MGS should remain fully closed during charging, while the low-side blue handwheel should be fully open (turned fully COUNTER-CLOCKWISE).

[msrichmond]

Anything is possible with pressure readings of zero on the high side and 85 PSI on the low side. But let's start with the simple stuff.

Are you sure you have the low-side adapter's thumbwheel fully open (turned fully CLOCKWISE) so that it's also opening the Schrader valve inside the service port adapter and not just charging into the hoses on the Manifold Gauge Set?

Do you have the hoses attached correctly to your MGS? Some hoses might not permit flow if installed incorrectly.

Is the R/D installed in the correct orientation? There's usually an arrow on it indicating the direction-of-flow, which should be from the condenser toward the TXV.

You're right, the high-side red handwheel on the MGS should remain fully closed during charging, while the low-side blue handwheel should be fully open (turned fully COUNTER-CLOCKWISE).

I am going to draw a map of my install to verify direction of flow. In the meantime, I checked the thumbwheels (both fully clockwise) and the hose orientation (knurled ends on the manifold).

I am noticing one thing though... on the fitting end of the hoses, the fittings are tight against the hose ends. In the photos of the product (a Four Seasons 59199) the fittings show a small gap between the end of the fitting and the end of the hose.

[msrichmond]

Anything is possible with pressure readings of zero on the high side and 85 PSI on the low side. But let's start with the simple stuff.

You're right, the high-side red handwheel on the MGS should remain fully closed during charging, while the low-side blue handwheel should be fully open (turned fully COUNTER-CLOCKWISE).

WAIT... I did not have the low side open! When I did open it, the low side pressure dropped to 65PSI but the high side pressure is stilll zero. I'll try again ASAP to run the engine to see if the compressor comes on, but first I am going to do that diagram.

[JohnHere]

I am going to draw a map of my install to verify direction of flow. In the meantime, I checked the thumbwheels (both fully clockwise) and the hose orientation (knurled ends on the manifold).

Good idea on drawing the direction-of-flow map, especially because you're new at this.

With your Manifold Gauge Set, the red and blue hoses can attach only one way, so we can scratch that off the list of possible problems. Double-check the yellow hose, though. Some of them will have a check valve inside one of the knurled fittings. If yours does, the check valve should be at the end that attaches to the refrigerant can or cylinder.

Incidentally, always charge refrigerant gas—never liquid—into the low side, which means the can or cylinder should be upright, not inverted.

I am noticing one thing though... on the fitting end of the hoses, the fittings are tight against the hose ends. In the photos of the product (a Four Seasons 59199) the fittings show a small gap between the end of the fitting and the end of the hose.

I don't think that makes any difference. It's just the way the ferrules and fittings were installed and crimped at the factory.

WAIT... I did not have the low side open! When I did open it, the low side pressure dropped to 65PSI but the high side pressure is stilll zero. I'll try again ASAP to run the engine to see if the compressor comes on, but first I am going to do that diagram.

Ahhh...I'm sure that was the problem. If you're not seeing any pressure on the high side, it's probably because you don't have enough refrigerant in the system yet. Start the engine, set it about 1,800 RPM, and turn on the system: Max A/C, blower on Medium or High, windows and doors open, and airflow directed to the dash vents. Then begin charging it again. The compressor won't engage until you have enough refrigerant in the system to overcome the low-pressure threshold of the trinary switch.

Where is the trinary switch located, on the R/D?

[msrichmond]

Where is the trinary switch located, on the R/D?

Yes.

[msrichmond]

I am going to draw a map of my install to verify direction of flow. In the meantime, I checked the thumbwheels (both fully clockwise) and the hose orientation (knurled ends on the manifold).

Good idea on drawing the direction-of-flow map, especially because you're new at this.

[JohnHere]

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.