Service Manual

627333-A 8-11
Air Dryer
AIR DRYER COMPONENTS
FIG. 5: Air dryer assembly.
(1) Heater
(2) Turbo Cut-off Valve
(3) Desiccant Cartridge
(4) Outlet Check Valve
(5) Regeneration Valve
(6) Purge Valve
Heater
FIG. 6: Heater is located in air dryer base. Heater
prevents water that collects in air dryer from freezing.
The heater consists of a cylindrical resistive-type
heating element and small circular thermostat. Heater
is 12-volt.
To replace heater, disconnect electrical plug. Remove
screws, receptacle and O-ring from base to access
retainer screw. Remove entire screw and remove entire
heater assembly. Install new element and thermostat in
cavities. Install new retainer and screw to hold element
and thermostat in place. Install new O-ring and
receptacle and fasten in place with screws.
Turbo Cut-off Valve
FIG. 7: Turbo cut-off valve is located in inlet port of air
dryer. The turbo cut-off valve closes path between air
compressor and air dryer purge valve during
compressor unload. This prevents a loss of
turbocharger boost pressure during a compressor
unload cycle, keeping boost pressure for maximum
engine horsepower.
IMPORTANT: There is no spring in the turbo cut-off
valve assemblies used on U Series air dryers.
To replace turbo cut-off valve, remove snap ring. Cover
and spring may fall out of bore. Remove desiccant
cartridge. Use a wooden stick to push piston spring and
cover out if they don’t fall out. Clean and inspect the
valve bore. If bore is damaged so that a tight seal
cannot be maintained, replace air dryer.
Install new lip seal on piston. Seal lip must face up
toward top of piston. Install new O-ring on cover. Use
grease supplied with kit to apply thin film to valve bore
and O-ring. Install new piston with flat side toward
dryer. Install new spring, cover, and snap ring to hold
components in place. Install plug. Replace desiccant
cartridge.
FIG. 5
M6205002
1
4
6
5
2
3
FIG. 6
M6215001
FIG. 7
M6215002