Whirlpool Dryer Various Test Procedures - Part 2

TEST #4 Heater
This test is performed when either of the following situations occur: Dryer does not heat Heat will not shut off
This test checks the components making up the heating circuit. The following items are part of this system:
Harness/connection, Heater relay, Thermal cut-off, Thermal fuse, High limit thermostat, Gas burner assembly,
Centrifugal switch, Exhaust thermistor, Machine control electronics, Gas supply. Dryer does not heat:
1. Unplug dryer or disconnect power.
2. Remove the back panel to access the thermal components.
3. Perform TEST #4b. If the thermal fuse is OK, go to step 4.
4. Perform TEST #4c. If the thermal cut-off is OK, go to step 5.
5. Locate the high limit thermostat. Measure the continuity through it by connecting the meter probes on the
red wire and blue wire terminals. If there is an open circuit, replace the high limit thermostat and thermal cutoff.
Otherwise, go to step 6.
6. Perform TEST #4d. If this is OK, replace the machine control electronics.
Heat will not shut off:
1. Unplug dryer or disconnect power.
2. Access the machine control electronics, remove the P14 connector, then measure the resistance between P14-3 (red-white wire) and P14-6 (red-white wire) at the connector. If 5–15 k ohms are measured, replace the machine control electronics. If the resistance is greater than 20 k ohms, replace the exhaust thermistor.
TEST #4a Exhaust Thermistor
The machine control electronics monitors the exhaust temperature using the exhaust thermistor, and cycles the heater relay on and off to maintain the desired temperature. Begin with an empty dryer and a clean lint screen.
1. Plug in dryer or reconnect power.
2. Start the Timed Dry cycle.
3. If after 60 seconds, F-22 or F-23 flashes in the display and the dryer shuts off, the thermistor or wire harness is either open or shorted. Unplug dryer or disconnect power. Check wire connections at the machine control electronics and thermistor. If wire connections are OK, check exhaust thermistor resistance per step 5.
4. If F-22 or F-23 does not flash in the display, the connections to the thermistor are good. Therefore, check the exhaust temperature value at any or all of the temperature levels in question, using the Timed Dry cycle, and the following process: Hold a glass bulb thermometer capable of reading from 90° to 180°F (32° to 82°C)
in the center of the exhaust outlet. The correct exhaust temperatures are as follows:
TEMP
SETTING HEAT TURNS
OFF* HEAT TURNS
ON High 155° ± 5°F
(68°± 3°C) 10–15°F
(6–8°C)
below the
heat turn off
temperature Medium 140° ± 5°F
(60°± 3°C) 10–15°F
(6–8°C)
below the
heat turn off
temperature Low 125° ± 5°F
(52°± 3°C) 10–15°F
(6–8°C)
below the
heat turn off
temperature Extra Low 105° ± 5°F
(41°± 3°C) 10–15°F
(6–8°C)
below the
heat turn off
temperature The measured overshoot using the glass
bulb thermometer in the exhaust outlet can
be 30°F (17°C) higher.
5. If the exhaust temperature is not within specified limits, or you have come here from step 3, remove the P14 connector, then measure the resistance between P14-3 (red-white wire) and P14-6 (redwhite wire) at the connector. If the resistance is OK, check P14-3 and P14-6 to machine ground. If resistance is greater than 0 (zero), replace wiring harness. NOTE: All thermistor resistance measurements must be made while dryer is
disconnected from power. The following table gives temperatures and ranges for the associated thermistor resistance values.
Temp
F C
Res
kΩ
Temp
F C
Res
kΩ
50° (10°) 19.0 -22.0 80° (27°) 8.5-10.5 60° (16°) 14.8-16.8 90° (32°) 6.8-8.8 70° (21°) 11.5-13.5 100° (38°) 5.0-7.0 If the thermistor resistance does not agree with table, replace the exhaust thermistor. If the thermistor resistance checks agree with the measurements in the table, replace the machine control electronics.
TEST #4b Thermal Fuse
The thermal fuse is wired in series with the dryer drive motor.
1. Unplug dryer or disconnect power.
2. Access the thermal fuse by first removing the back panel.
3. Using an ohmmeter, check the continuity across the thermal fuse. If the ohmmeter indicates an open circuit,
replace the failed thermal fuse.
TEST #4c Thermal Cut-Off
If the dryer does not produce heat, check the status of the thermal cut-off.
1. Unplug dryer or disconnect power.
2. Access the thermal cut-off by first removing the back panel. .
3. Using an ohmmeter, check the continuity across the thermal cut-off. If the ohmmeter indicates an open circuit,
replace the failed thermal cut-off and high limit thermostat. In addition, check for blocked or improper exhaust
system.

TEST #4d Gas Valve
1. Unplug dryer or disconnect power.
2. Access the gas valve by removing the front panel and drum assembly.
3. Use an ohmmeter to determine if a gas valve coil has failed. Remove harness plugs. Measure resistance across terminals.