I have an older Wayne compressor that has been a work horse for 15 plus years for me. Model 6885-SH, two cylinder, two stage. It’s running a 5 hp, 240V, single phase magnetic start motor, with a disconnect switch with two 20A fuses. That is off a main panel with a 30A breaker. It just started blowing one (the same) 20A fuse on one leg of the disconnect switch. It does this at random intervals. Replace the fuse, it runs like it always has in the past. It was suggested by the owner of the electrical supply here that the unloader valve may be sticking, and the resultant head pressure is causing the motor to kill the fuse on start up. Any input or suggestions? Searched on Garage Journal but came up zip. Know where I can get a manual with parts diagram? Thanks!
If your compressor is inside your shop/garage and you've often attacked metal with a grinder or a chop saw, the first thing I'd do is take your air gun and blow the heck out of the electrical components on the compressor. Take off any covers to better your access and have at it. I have no idea if this could be your problem but it's cheap and it's what worked for me when my 220volt welder blew a small glass fuse that is part of the welder, not part of the power supply to the welder. Worth a try.
The symptoms you describe is caused by one of two issues, either mechanical or electrical. Electrical can be a motor capacitor going bad, a motor winding issue, or an intermittent short. How is the pressure switch wired-on the same leg as the blowing fuse? A mechanical issue with the compressor can cause a high amp draw on start/restart. One test would involve removing the drive belts and cycle the motor on and off by jumping the pressure switch. On the mechanical side, you should hear the unloader valve releasing pressure after the cut-out pressure is reached, albeit quickly.
The Jalopy Journal
