Service manual
6-- 20T--318
6. The display module will go blank briefly and then dis-
play “541 00.” Based on the operational software
installed.
7. Press the UP or DOWN ARROW key to scroll
through the list to obtain the proper model dash num-
ber. (If a defective card is being used, the display will
blink the message “bAd CArd.” Turn start-stop
switch OFF and remove the card.)
8. Press the ENTER key on the keypad.
9. When the software loading has successfully com-
pleted, the display will show the message “EEPrM
donE.” (If a problem occurs while loading the soft-
ware, the display will blink the message “Pro F AIL” or
“bad 12V.” Turn start-stop switch OFF and remove
the card.)
10.Turn unit OFF using start-stop switch (ST).
11. Remove the PCMIA card from the programming/-
software port and return the unit to normal operation
by placing the start-stop switch in the ON position.
12.Confirm correct model configuration using the key-
pad to choose code select 20 (CD20). The model
displayed should match the unit serial number plate.
6.21.4 Removing and Installing the Controller
a. Removal:
1. Disconnect all front wire harness connectors and
move wiring out of way.
2 The lower controller mounting is slotted. Loosen the
top mounting screw (see Figure 6-26) and lift up and
out.
3 Disconnect the two back connectors (EC) and re-
move module.
4 When removing the replacement controller from its
packaging, note how it is packaged. When returning
the old controller for service, place it in the packaging
in the same manner as the replacement. The pack-
aging has been designed to protect the controller
from both physical and electrostatic discharge dam-
age during storage and transit.
b.Installation:
Install the module by reversing the removal steps.
Torque values for mounting screws (item 2, see
Figure 6-26) are 0.23 mkg (20 inch-pounds). Torque
value for the connectors is 0.12 mkg (10 inch-pounds).
6.21.5 Battery Replacement
If required, use tool 07-00418-00.
6.22 TEMPERATURE SENSOR SERVICE
Procedures for service of the Return Recorder , Return
Temperature, Supply Recorder, Supply Temperature,
Ambient, Defrost Temperature, Compressor Discharge
and Compressor Suction temperature sensors are
provided in the following sub paragraphs.
6.22.1 Sensor Checkout Procedure
To check a sensor reading, do the following:
a. Remove the sensor and place in a 0 degrees C (32
degrees F) ice-water bath. The ice-water bath is pre-
pared by filling an insulated container (of sufficient
size to completely immerse bulb) with ice cubes or
chipped ice, then filling voids between ice with water
and agitating until mixture reaches 0 degrees C (32
degrees F) measured on a laboratory thermometer.
b. Start unit and check sensor reading on the control
panel. The reading should be 0 degrees C (32 de-
grees F). If the reading is correct, reinstall sensor; if it
is not, continue with the following:
c. Turn unit OFF and disconnect power supply.
d. Refer to paragraph 6.21 and remove controller to gain
access to the sensor plugs.
e. Using the plug connector marked “EC,” that is con-
nected to the back of the controller , locate the sensor
wires (RRS, RTS, SRS, STS, AMBS, DTS, CPDS
OR CPSS as required). Follow those wires to the con-
nector and using the pins of the plug, measure the
resistance. Values are provided in Table 6-1.
Table 6-1 Sensor Temperature/Resistance Chart
Temperature
Centigrade
Temperature
Fahrenheit
Resistance
(Ohms)
RRS, RTS, SRS and STS:
0 32 32,650 +/-- 91
25 77 10,000 +/-- 50
AMBS and DTS
0 32
32,650 + 1720
- 1620
25 77
10,000 + 450
- 430
Due to the variations and inaccuracies in ohmmeters,
thermometers, or other test equipment, a reading
within 2% of the chart value would indicate a good
sensor. If a sensor is defective, the resistance read-
ing will usually be much higher or lower than the resis-
tance values given.
6.22.2 Sensor Replacement
a. Turn unit power OFF and disconnect power supply.
b. For two wire sensors, cut cable 5 cm (2 inches) from
shoulder of defective sensor and discard the defec-
tive sensor only. For 3-wire sensors, cut at 23 cm (9
inches). Slide the cap and grommet off well mounted
sensor and save for possible reuse. Do not cut the
grommet.
c. If required, prepare the replacement sensor by cut-
ting sensor wire(s) back 40 mm (1-1/2 inch). For
3-wire sensors, the black wire should be cut at the
middle length and the red/white wire cut to the shorter
length (See Figure 6-27).