Compressor Current Draw, Pressure Output & Leak Down Test

Fig. 7 Compressor current draw, pressure output & leakdown test connections:

1. Disconnect wiring from compressor motor and exhaust solenoid terminals.
2. Disconnect pressure line from air dryer and connect a pressure gauge, J-22124-A, to air dryer fitting.
3. Connect an ammeter to a 12 volt source and the compressor. The current draw should not exceed 14 amps. When the pressure gauge indicates approximately 100 psi, deactivate the compressor and observe if the pressure leaks down.
a. If the current draw exceeds 14 amps., replace the compressor.
b. If compressor is inoperative, remove the two motor case retaining screws and pull case and magnet assembly off armature. Inspect inside of motor case for any foreign material that could bind or lock up armature. Make sure that positive brush lead is not grounded and that ground brush lead connection is clean and tight. Make sure that brush spring is properly positioned. If no defects can be found, replace motor and cylinder assembly.
c. If pressure build up is satisfactory but leaks down below 90 psi (but not to 0 psi) before holding steady, replace the solenoid valve.
d. If pressure leaks down to 0 psi or does not build up to 110 psi, attach pressure gage J-22124 and pressurize compressor/dryer assembly to 100 psi through gage fill valve. Using a soap solution, check compressor and dryer for leaks. If leak is found around dryer O-ring casting bore, replace O-ring. If leak is found around service valve, tighten or replace service valve. If leak is found around edge of cover gasket, torque cover bolts to 36 inch lbs.; if leak persists, replace gasket. If leak is found around edge of solenoid valve or head casting air intake and exhaust opening, replace solenoid valve. If leak is found around dryer cover, replace dryer.
e. Referring to step d above, if pressure did not build up to 110 psi and the leak test did not reveal any leaks, replace motor and cylinder assembly.