DUAL DRYER SYSTEM
INSTALLATION/SERVICE
MANUAL (L31279)
®
Testing The GeminiMDx
Before placing the vehicle in service, perform the
following tests:
1. Close all reservoir drain cocks.
2. Build up system air pressure to governor cut-out
and note that the GeminiMDx dryer purges with an
audible exhaust of air.
3. Check for air leaks by applying a soapy water
solution around the dryer manifolds, banjo bolts,
pipe fittings, and dryer base.
4. Actuate the service brakes to reduce system air
pressure to governor “cut-in” pressure and ensure
the compressor is in a loaded cycle. Note that the
system once again builds to full pressure and is
followed by a purge.
5. In order to check the Consep / ADV for proper
operation the compressor must be in the
compressor loaded cycle and the air governor must
be between “cut-in” and “cut-out” pressure. This
step can be performed concurrently with step 3.
a. Check the Consep for air leaks by applying a
soapy water solution around the manifolds,
banjo bolts, pipe fittings, and ADV mounting
area and drain port.
b. Observe the ADV for an audible click, either
during a brake application, timer function, or
multiplexing signal. As the ADV clicks, and
compressor loaded and governor between
“cut-in” and “cut-out”, the drain will expel a
small “puff” of air. If contaminants are present,
they will be expelled with the “puff”.
c. Perform a manual drain test by depressing the
red button on the bottom of the valve.
d. To check the ADV valve’s heating element, turn
on the vehicle’s ignition. Wait ten minutes. The
valve should be warm to the touch.
6. Operational check of air dryer heater:
a. The heater can be checked while in the air
dryer housing.
b. The air dryer temperature must be below 45°F
(thermostat closing temperature) to check the
heater resistance.
c. Set volt-ohmmeter to ohms.
d. Disconnect the electrical plug.
e. Connect the continuity tester to the heater
element terminals.
6. f. Measure the resistance
Acceptable 12VDC: 1.4-1.8
W
Acceptable 24VDC: 5.9-6.9
W
g. Replace heater if 12VDC is <1.4
W
or 24VDC is <5.9
W.
7. It is recommended that the vehicle be tested for
leakage using the following procedure to assure
the GeminiMDx will not cycle excessively.
a. Apply the parking brakes, build system pressure
to governor cut-out and allow pressure to
stabilize for at least one minute.
b. Observe the dash gauge pressures for two
minutes and note any pressure drop. Pressure
drop should not exceed 4 PSI with brakes
released and 6 PSI with brakes applied. Any
noticeable leakage must be repaired to avoid
excessive dryer cycling.
9.
Charge Cycle Time:
During normal, daily
operation the compressor should recover from
governor cut-in to governor cut-out in 90 seconds
or less at engine RPM’s depending on vehicle
vocation.
10.
Purge Cycle Time:
During normal, daily
operation the compressor must remain unloaded
for a minimum of 30 seconds between charge
cycles. This minimum purge time is required to
ensure complete regeneration of the desiccant.
Operational Check
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