Air Compressor Starting Update

The capacitors are not that expensive. Get the info from the capactors and purchase two new capactors. Unless you have the right equipment, you really can not check them at home. A ohm meter check will only tell if they are shorted and not if the capactance has changed.

Paul T.

True, however a motor repair shop may be able to test them for you. Like Paul says though, they're cheap. If you have trouble finding a place that either can or will test them for you, then it's not like you'll be breaking the bank on a guess. Back in the old days of basic electronics training in the Air Force we used to charge up a capacitor and short it across the backside of anyone caught sleeping in class. That was certainly proof that the capacitor was working, though not a very accurate test of its capacitance. Not sure I would recommend you bring them up into the bedroom to make sure they're working...

Any chance that centifugal switch is dirty? or stuck? The one that engages the Cap when the motor is starting

Doug

If you have a multi-meter remove the capacitors. Set the meter to the highest ohms scale. Observe the meter while you connect it to the leads of the capacitor. The needle should kick up and then slowly return to near "infinite" as the capacitor charges. If there is no kick the capacitor is "open". If the reading remains at a low ohms reading the capacitor is shorted.

Be sure to short the leads together before doing this. If the cap has a charge when you test it, the multimeter is not going to like it.