TM 5-4520-253-13
l N S P E C T / T E S T / R E M O V E / l N S T A L L S A F E T Y T H E R M O S T A T S A N D F L A M E
S W I T C H A N D B R A C K E T A S S E M B L Y ( C O N T )
8.
9.
10.
11.
Check thermostat (12) for cracks, dents, or other signs of damage or overheating.
Check flame switch and bracket assembly (4) for bends, broken welds, and damage to flame
switches (13 and 14).
Check terminal connections of wires (15) for good electrical contact.
Replace defective thermostat (12) or flame switch and bracket assembly (4).
TESTING:
1. Test both overheat thermostats according to the same procedure as follows:
a.
b.
c.
d.
3-106
Disconnect quick disconnect terminals ( 1 ) of
wires (2) from thermostat (3).
Connect terminals (4) of thermostat (3) in
series with volt ohmmeter using heat re-
sistant, insulated wires.
Place thermostat in heating chamber along
with accurate thermometer.
Thermostat contacts must open between 253°
and 267° F (123° and 131°C). Turn off heat
and allow thermostat to cool. Thermostat contacts must close between 227° and 243° F
(108° and 117°C). Replace thermostat that fails to operate within these limits.
