TM 5-2420-230-24-2
A/C Cylinder Head (QE Models) (012-104)
B3.9 and B5.9 Series Engines
Page 12-36
Section 12 - Compressed Air System - Group 12
E-Type Air Compressor
Holset SS model air compressors built with the E-Type
unloader can be identified by the letter "E" (SS296E, and
SS338E) and by the caution on the dataplate.
All QE (QE296 and QE338) model air compressors are
equipped with the E-Type unloader.
E-Type System with Air Dryer
Vehicles equipped with air dryers vented to the atmosphere
during unloaded compressor operation, using the Holset
E
-Type air compressor, require the installation of an econ
valve to prevent excessive oil consumption.
NOTE: Some air dryers can have a built-in econ valve.
Check with the manufacturer as to which type is installed.
E-Type System without Air Dryer
Air systems without air dryers, or with air dryers not vented
to the atmosphere during unloaded compressor operation,
can use the Holset E-Type unloader valve without modify-
ing the air system.
L-1240