TEST PROCEDURES-STEWART - WARNER AND HUPP HEATERS= Continued
ACTION
RESULTS
REMARKS
THINGS TO CHECK
14. Check operation of overheat switch as follows-Continued
d. Place pyrometer/thermometer in the center of the duct approximately 42 inches (1067-mm) from the
heat exchanger outlet,
e. If overheat switch does not engage or test light does not go out when outlet air temperature reaches
325° to 475°(167.2°C to 241.1 ‘C), proceed to step 16.
15. Check operation of valve thermostat for Stewart-Warner models.
Check thermostat for cracks, loose or damaged terminals, and distortion. Thermostat must be closed when
temperature is reduced between 43° and 57°F. Thermostat must open when temperature rises between 65°
and 75°. If thermostat is questionable, it can be checked using a multimeter set to the ohms function, while
chilling thermostat with ice. Do not immerse in fluids. Body temperature can be used to provide enough heat
to warm it to above 75° to check opening point.
16. Power control test procedures.
a. Connect two 100 watt resistors in parallel to substitute the igniter load for the voltage regulator. At-
tach the parallel resistors or an igniter to Module lead “E” (1).
b. Connect module lead “G” (2) and power supply’s ground or negative terminal together.
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TM 9-2540-205-24&P
