TM 9-2350-261-34 20. Turn the heater control switch to OFF. Fuelflow and burning should stop in about 30seconds. Blower should continue to run from1 to 3 minutes and then stop. If blowerdoes not work within limits, readjust theflame detector switch (see your -20). If theblower still fails to work within limits,replace the flame detector switch(see your –20).TESTING RESTRICTION THERMOSTAT AND THERMOSTATIC SWITCH 21. Turn the heater on and run it until thecoolant is hot enough to make the heatercycle from high to low heat. Leave theheater alone, then take the temperature ofthe coolant. The temperature should bebetween 140°F (60°C) and 170°F (76°C). Ifcoolant temperature is not within limits,replace restriction thermostat (page 14–51).22. After testing the restriction thermostat,close circuit across terminal board terminalsNo. 4 and No. 5, to make the heater stayon high heat. Heat the coolant until theheater burning stops. Check the temperatureof the coolant, it should be not less than220°F (104°C) or more than 250°F ( 21°C).If the coolant temperature is not withinthese limits, replace the thermostatic switch(page 14–53).N O T EThermostat shown in fuel control valve isset to open at 70°F (21°C) and to close at30°F (-1°C). If temperature is below 70°F(21°C), the heating element in fuel controlvalve can be energized during anyoperational cycle. FOLLOW-THROUGH STEPS 1. Install coolant heater in carrier(see your -20).END OF TASK14-66
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