4-2. Unit Troubleshooting (Cont)..
TEST OR INSPECTION
Use extreme caution when opening draincock. Wear safety goggles to protect
against eye Injury due to high pressure air.
When the draincock is closed, the pressure protection valve will pulsate as the
auxiliary air reservoir refills.
Open the draincock on the auxiliary air reservoir. When the draincock is opened, a strong air flow from
the reservoir should be evident. Close draincock.
If there is no pressure in the auxiliary air reservoir but there is pressure in the brake reservoirs,
replace the pressure protection valve at the inlet to the auxiliary air reservoir (see paragraph 4-24).
If there is pressure in the auxiliary air reservoir and brake air reservoir, check the throttle control
valve and the air control valves for defects and replace them as necessary (see paragraphs 4-37 and
10. SPRINKLER VALVES DO NOT OPERATE.
Check all air lines, throttle control valve, air reservoirs, sprinkler nozzles, and air control valves for air
leaks (see Figure 4-4).
Perform Malfunction 9, step 2.
Perform Malfunction 9, step 3.