MastercoolRefrigerant Leak Detector with Metal Oxide Gas Sensor, IntellaSense II, 55900, Blue

Great product,does its job flawlessly

I used to use a Harbor Freight detector before this for R-134a vehicle applications. Those inexpensive detectors from HF, and other imports here on Amazon can work to a degree, but when it came time for a replacement I did the research and selected this Mastercool 55900. The 55900 has proven to be superior overall to the more entry level tools.User interface wise you can both control the volume and mute the tones. The self test LEDs, sensitivity LEDs, and detection LEDs are all green in color and of high brightness so you can easily see them in sunlight. You can control the degree of sensor sensitivity via the touch pad controls as well.Features wise the tool comes in a rugged shop grade storage case, and includes two Energizer C batteries (I recommend you always store the tool with the batteries removed to prevent damage to the tool from them leaking if you are not using the tool regularly). Easy to read and understand instructions are included in hard copy, as well as via a PDF on the Mastercool website. Mastercool includes a small glass vial of a test gas that you can use to check that the tool remains functional and in calibration. A very professional and high quality touch.However, I only gave this tool 4 starts out of 5 because I found it often required multiple passes to confirm the location of very small R-134a leaks, and with the sensor housing in nearly direct contact to the hose or pipe itself. These are leaks I would not expect lower cost tools to detect at all, and so the rating is less a reflection on the 55900 and more on the abilities of electronic detectors in general. I only use them as a last resort when R-134a dye injection is not an option.

The box arrived broken

Does not perform as advertised. Not accurate. Does not provide repeatable results. Absolutely will not work with any amount of air moving across the tip, such as from HVAC vents in a vehicle. Constantly freaks out and goes into “interference” mode. Sent it back to the manufacturer to be repaired and it came back working the same.

Not as easy to use as it should be. Had to take it apart to find a screw rattling round in it and figure out where it went. Instructions are not very clear on how to use it.

did not do as promised and returned for a full refund

The dtector is problem the blinking andnno function whats is the warranty?