Review on Orion Motor Tech AC Gauges: Complete 3-Way Automotive AC Manifold Gauge Set with Hoses, Couplers & Adapter for R134a R12 R22 R502 - Freon Recharge Kit for HVAC by Andrew Amzallag

I am not an air conditioning expert and have no experience diagnosing or repairing air conditioning. The gauges were easy to assemble and use. The sensors are in Celsius as others have commented. Gauges come with everything needed for R-134a systems except for a canister faucet and an adapter is included to convert from a gauge kit to a canister faucet which I purchased separately (I have my own R-134a Faucet bought locally, but it's similar to taps offered on Revain by WINOMO or Interdynamics DV-134). The gauge hose fits on the underside of the R-12 system with the R-134a quick disconnect removed, but this requires a high side adapter which I don't need and didn't consider as I only use it for filling used a can . in an old truck. I bought a Robinair 10102 sidecock for an R-12 tank that worked well and came in two different sizes, one the size of a yellow gauge hose that just screwed on and the other on the sidecock. an adapter is included with this kit, if you want to do it for no reason, then screw the yellow hose onto the adapter. With the R-12 system, for example, the measuring hose connections for the yellow and blue hoses are screwed directly onto the faucet fitting and the lower fitting in the vehicle. For the R-134a system, the included quick couplers fit the top and bottom ports on the vehicle and the included adapter fits the tank valve. The sensors worked perfectly on the two cars I worked on today and overall the quality seems average to acceptable. This set of OrionMotorTech gauges allows you to see exactly what's going on with the R-134a system (not R-12 without the additional purchase of a high side adapter). These gauges are MUCH better for charging an R-134a system than an R-134a refrigerant cylinder with a cheap one-piece gauge and short hose sold for charging systems. In my experience they have always been frustratingly inaccurate and I think they are useless. As far as you know what you're doing to diagnose and fill, it's not easy to find accurate checking/filling and gauge pressure readings online, but this worked for me: Vehicleairconservices/page/gauge_readings. Start with the car on and the A/C off and use the appropriate pressure chart. I believe this checks the overall fill pressure of the system and if it's generally low then it probably needs topping up. Then, with the windows down, turn on the air conditioning to maximum, bring the car up to normal operating temperature, and use the air conditioning specified in the table. Some basic diagnostic information is also included. Use all of this information at your own risk. I'm no expert, as I said, very new to air conditioning, but I'm a certified backyard mechanic. In my opinion good value for money.