My Panasonic Inverter CU-E24HKR split air conditioner that generally seems to work well, will not now turn off completely with the remote control. The outside unit hums at 50 cycles/sec loudly - The only way to stop it is to turn off the units main switch... The switch can be turned back on again immediately without the hum comming back. Is there a way to reset the air conditioner??? Cheers Eric