Review on JIFETOR 3 Way AC Manifold Gauge Set: HVAC Diagnostic Freon Charging Tool for Auto Household R12 R22 R404A R134A Refrigerant by Charlie Wilson

I used it to charge my air conditioner and measure the pressure. It worked fine the first time, but I left it plugged into my car overnight to see if the pressure changed or if there were any leaks, but when I pulled it out the next day the gauge needles stayed where they were they were moving. down to zero. So the instructions say you use the adjustment screw to set it to zero. I tried to do this but the reading seemed very far away as I know the pressure must be higher because I added more refrigerant to the system than the first time, but the pressure reading was too low , so recalibrating with the adjustment screws doesn't seem reliable. It was fine for the one time I used it, but would help if it lasted longer. I'm not sure I would use this along with a vacuum pump to check for leaks as the gauges get stuck in one position after a reading. Everything else like the hoses and fittings seemed fine, I'll let them, but the seller says they only give a one year warranty on the fittings, but I'm wondering if they give a warranty on the gauges or if they do can swap them out for another function one a set of pressure gauges how can i leave the hoses and everything else that came with it. Considering what I paid for it, I got away with it at least once.