Automotive Air Conditioning Information Forum

Just Took AC Pressures Using Gauge; AC not cooling
When compressor is off/engine off LOW: 45 PSI, HIGH: 50 PSI

When compressor is on LOW: 0 PSI, HIGH: 100 PSI

2002 Accord

Compressor is engaging

Even if I keep filling with refrigerant, it stays at 0 PSI when compressor on. I don't want to overfill.

What's the issue here?

Are you sure that your low-side hose adapter from the Manifold Gauge Set is securely connected to the car's low-side port, that the thumbwheel is fully open, and that refrigerant actually is flowing into the system?

From the static pressures that you posted (no ambient temperature given), it's probable that the system is low on refrigerant due to a leak. To charge it properly, the leak(s) must first be located and repaired and the receiver/dryer replaced. Then the system will need to be evacuated well and recharged with pure R-134a (containing no sealers or other additives) using an accurate refrigerant scale.

Note that you won't be able to charge the system by pressures alone. The specs that I have for your car call for 23 ounces net weight of R-134a or approximately two of the small 12-ounce cans.

Per the experts here, the most common reason for mobile AC failure is low charge.
A major suspect area would be the evaporator under the dash.
Check your couplings as suggested, and rent or buy an electronic sniffer, and sniff everywhere there is a connection. Sniff the bottom of the fitting, refrigerant is heavier than air.
For the evap, get under the car and put the sniffer probe into the drain of the evap, any leaking refrigerant will sink down into the bottom of the case and out the drain line