TM 5-4520-256-14
3-9. TROUBLESHOOTING - Continued.
Table 3-2. Unit Troubleshooting - continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
7.
RETURN AIR TEMPERATURE IS HIGHER OR LOWER THAN DESIRED - Continued.
Step 2.
Check the air temperature in the shelter at the return air duct hookup.
If the air temperature is higher or lower than desired, proceed to step 3.
Step 3.
Check the temperature adjustments on the temperature controller and adjust as necessary.
If adjustment of the thermostat does not correct the shelter temperature, proceed to MALFUNCTION 9.
8.
NO SPARK AT BURNER.
Step 1.
Set OFF/VENT/HEAT switch (S1) to VENT mode and observe for a spark at the burner through
sightglass.
If spark is visible, unit is functional.
If no spark is visible, proceed to step 2.
Step 2.
Set switch (S 1) to the OFF position and disconnect the power cable. Proceed to step 3.
Step 3.
Disconnect and tag the wiring lead from terminal 6 on (S1) going to the transformer. Proceed to step
4.
Step 4.
Check continuity across ignition transformer primary leads (para 3-26).
If continuity check indicates an open circuit, replace transformer.
If continuity check indicates continuity, proceed to step 5.
Step 5.
Reconnect wire lead disconnected in step 3 to terminal 6 at (S1). Proceed to step 6.
Step 6.
Disconnect the high tension leads from the transformer and check for continuity across the
secondary of the transformer.
Change 3 3-12
