2003 Ford Taurus - Compressor not engaging

[JohnHere]

Besides the last statement, what did I do incorrectly here, and why is it venting with what should be the correct weight of charge?

The pressures are reasonable at idle, but I would re-check pressures at about 1,800-2,000 RPM to determine whether the high-pressure side is actually too high. Ordinarily, the pressures—if within normal range—shouldn't cause refrigerant to vent through the High Pressure Relief Valve (HPRV).

With further testing, the high-side pressure might prove to be too high, or the HPRV could be shot.

The HPRV is a one-time valve—that is, once it vents, it needs to be replaced. Unfortunately, the system will have to be recovered again to replace it.

The under-hood decal shows the same specification for R134a that I have: 34 ounces net weight.

[DSK]

Thanks John, I'll test it at 1800 RPM and check pressures again.
I'm not seeing separate HPRVs offered locally at part stores or online, including ACKits. I wonder where they can be had. I only see them attached to the manifold hose assembly.

[JohnHere]

You should be able to find the correct HPRV at your local Ford dealer. Bring the old one with you, if possible, along with the engine specs and compressor maker, so that they can match it for you. If memory serves, I believe 3 or 4 different V6 engines were offered for the 2003 Taurus. I'm unsure whether the HPRV differed for each engine.

It's also possible that the car has a combination of a bad HPCO (High Pressure Cut Off) switch that fails to shut-down the compressor under extreme pressure conditions, along with a condensing problem that's causing the high-side pressure to spike and the HPRV to vent. If so, you should be able to identify the abnormal high-side pressure when you re-test it and take the appropriate corrective action.

A word of caution: Be aware of unusually high pressures that result in venting refrigerant from the HPRV. Refrigerant that releases suddenly and unexpectedly is hazardous, especially to the eyes and exposed skin. To prevent this from happening, watch the high-side pressure carefully. If it starts to spike above normally expected levels, shut off the compressor right away until the cause is found and fixed.