How to use OT Compressor? (1 Viewer)

[Sixgun95]

Last week I tried it for the first time, it took numerous attempts to turn on by pressing the power button. I had the engine running, hooked up the hose, pressed power multiple time, then Walla, it came on and worked great. Just now I did the same, turned the car on, engine running, this time I left the hose off, pressed power, took maybe 3-4 presses to turn on. Am I doing something wrong? Cannot find specifics in the manual. I assume car needs to be running, press power once and it should come on?