TM 5-2410-240-23-1
0021
Table 1. Cab Troubleshooting Without Codes. - Continued.
0021
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
1. Little or No Warm Air Flow When
Test Step 3.
Heater Control Knob is Set for
1. Verify blower fan operation -
Fan Speed and Air Flow OK -
Maximum Heating Continued
Fully open all louver's and turn
Proceed to Test Step 4.
blower fan switch slowly from
Fan Speed OK, Air Flow Not OK
lowest setting through full
- Inspect HVAC recirculation cabin
range of operation. Fan speed
air filter for damage or blockage
and air flow should increase
(WP 0252).
with each position.
Fan Speed Does Not Respond In
One or More Positions - Refer to
HVAC blower motor does not
operate when the fan switch is
activated in this work package.
Test Step 4.
1. Ensure heater shutoff valves
Restriction - Flush hoses and
are in full open position (WP
heater core (WP 0043). If restric-
0247). If valves are OK, check
tion remains, replace affected
heater core for restriction/
component.
blockage and heater hoses for
No Restriction - Proceed to Test
kinks, restriction, and block-
Step 5.
age (WP 0247).
Test Step 5.
1. Using MSD (WP 0016), select
Does Not Display Heat - Position
Status Icon, Automatic Tem-
switch to heat setting.
perature Control and verify
Displays Heat - Proceed to step 2.
Cab Air Temperature Control
Switch Position parameter
indicates Heat in the Values
column.
2. Rotate the temperature control
Actuator Duty Cycle Parame-
switch from hot to cold and
ters Respond Correctly - Pro-
back while monitoring the Cab
ceed to Test Step 6.
Air Heater Engine Coolant
Actuator Duty Cycle Parame-
Actuator Duty Cycle.
ters Do Not Respond Correctly -
Percent duty cycle should
Machine ECM faulty. Replace
increase with commanded action.
equipment ECM (WP 0147, WP
0149).
0021-3
