Check Valve

CAUSE

REMEDY

1. Dryer is constantly “cycling”

Excessive system leakage.

With gauge installed at RES port of governor, pressure should

or purging. Dryer purges

IMPORTANT: Note whether air

not drop below ”Cut-In” pressure at the onset of the compressor

frequently (every 4 minutes

pressure loss is shown on dash

“Unloaded” cycle. If pressure drops, check for “kinks” or

or less while vehicle is idling)

gauge(s). Pressure loss shown on

restrictions in line connected to RES port. Line connected to

(continued).

gauges is caused by service brake

RES port on governor must be same diameter, or preferably

system or component leakage.

larger than, lines connected to UNL port(s) on governor.

Pressure loss NOT SHOWN

on gauges is caused by supply

system or component leakage.

(continued)

B. Leaking purge valve housing

B. With the supply port open to atmosphere, apply 120 psi at the

assembly and/or o-rings in air

control port. Apply a soap solution to the supply port and exhaust

dryer end cover.

port (purge valve seat area). Permissible leakage - 1" bubble in

5 seconds.

Holset® “E” type compressor.

C. Test the Holset® E Compressor unloader system with feedback

line and check valve for proper operation. Make certain Holset

ECON is not in use with the drop-in version of the air dryer, if

so, remove and retest.

When installing a Bendix Drop-In air dryer in a system equipped

with a Holset E or QE compressor, remove the Holset ECON valve

along with its feedback and governor control line.

Feedback Line

Typical Drop-In Air Dryer End Cover