FOR SERVICE TECHNICIAN ONLY - DO NOT REMOVE OR DESTROY
PAGE 16
TEST #4a Thermistors
Outlet Thermistor
The machine control electronics monitors the
exhaust temperature using the outlet 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. See Accessing &
Removing the Electronic Assemblies, page 21, and
for thermistor location, see figure 10, page 15.
If wire connections are OK, check the outlet
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:
EXHAUST TEMPERATURES
Temperature Heat Turns Off* Heat Turns On
Setting
°F (°C)
°F (°C)
High
155°±5° (68°±3°)
10–15°
Medium High 150°±5° (66°±3°)
(6–8°)
Medium
140°±5° (60°±3°)
below the
Low
125°±5° (52°±3°) heat turn off
Extra Low 105°±5° (41°±3°) 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, perform the following:
NOTE:
All thermistor resistance measurements
must be made while dryer is unplugged or
disconnected from power.
ALL DRYERS:
Remove the P14 (P4 in Amana
electric models) connector, then measure the
resistance between P14-3 (P4-3 in Amana
electric models) (red wire) and P14-6 (P4-6
in Amana electric models) (red wire) at the
connector.
If the resistance is OK, check P14-3 and P14-6
(P4-3 and P4-6 in Amana electric models) to dryer
ground.
If resistance is greater than 0 (zero), replace
wiring harness.
ALL DRYERS:
The following table gives
temperatures and their associated resistance
values.
OUTLET THERMISTOR RESISTANCE
Res.
Res.
Temp
Range
Temp
Range
°F (°C)
kΩ
°F (°C)
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 outlet thermistor.
If the thermistor resistance checks agree
with the measurements in the table, replace
the machine control electronics.
