I forgot to mention the specs that I have for your car: 16 ounces net weight of R-134a, and 4.4 fluid ounces of PAG-46 oil. However, if your car still has its under-hood A/C decal, go by those specs instead because the decal takes precedence.

A reading on the low side of 21 PSI at 1,500 RPM translates to an evaporator temperature (coincidently) of about 21°F, which will cause the evaporator to freeze-up and block airflow through the vents under certain conditions. It's also an indication that the system is undercharged. The Schrader valv...

I agree with the preceding comments. It appears to be low on refrigerant. Have the refrigerant recovered, then the system evacuated and recharged to specs, adding back the proper amount and type of oil if any was recovered along with the refrigerant. The ambient temperature is a bit low for MVAC wor...

The system is bumping into the High Pressure Cut-Off (HPCO). A few issues can cause that. Foremost is a blocked Orifice Tube (OT) that can prevent circulation of the refrigerant and oil and cause extremely high pressure to build up on the high side, which you noticed. The OT itself is inexpensive. H...

Has the compressor been replaced recently, and was it a brand-new unit? If so, what else was done at the same time, if anything?

I believe your car has a variable-displacement compressor. If so, you could try replacing only the compressor's control valve first. But with that amount of mileage on the car, I too would go ahead and replace the entire compressor/clutch assembly. I strongly recommend replacing both the condenser a...

After one hour, the HP and LP sides should equalize. If they don't, the cause is usually a defective metering device—in this instance, the TXV—and/or a blockage someplace. Presuming a full charge of refrigerant, if you're seeing only 100 PSI on the high side at an ambient temperature of 76°F, it doe...

Bill, if your password was a simple one, whomever did the hacking probably just got lucky, guessed it correctly, and logged right in. It's a good thing that you changed it right away because I'm sure your original PW has already made it onto the Dark Web and is now for sale, even though it's no good...

A few additional thoughts... You should hear a click when the clutch engages and then a running-compressor noise, which should be fairly low in volume and constant whenever the clutch is driving the compressor. If it's much louder than that—like the sound a steel-wheel roller skate would make whose ...

Other problems could be in play here, but yes, the clutch air gap might have become larger since the car was new. The largest the air gap would be is when the engine is cold, or in the morning on first start-up. It's not large enough to where the clutch will no longer engage, but it is to the point ...