![background image](http://html.mh-extra.com/html/thermo-king/super-ii-sr/super-ii-sr_manual_1104381056.webp)
Electrical Maintenance (Rev 6/98)
46
NOTE: The unit will not defrost during normal unit oper-
ation unless the defrost cycle is initiated while the evapo-
rator coil temperature is below 7.2° C (45° F).
When the frost has melted and the evaporator coil tempera-
ture reaches 13.9° C (57° F), the defrost cycle should termi-
nate. Immediately, the defrost light should go out, and the
unit should shift to the mode of operation determined by the
microprocessor setpoint and the air temperature sensors.
Defrost Cycle Checkout Procedure
CAUTION: Remove jumper wires from the unit
after checking or testing unit components.
To check the defrost cycle, run the unit on COOL until the
evaporator coil temperature is below 7.2° C (45° F). Push
the manual defrost button. If the unit continues to operate on
COOL, proceed to “Unit Does Not Defrost,” in this chapter.
If the unit shifts to DEFROST but the evaporator coil tem-
perature fails to rise, proceed to “Defrost Terminated On
Time Limit,” in this chapter.
Unit Does Not Defrost
If the unit continues on cooling, proceed to step 1.
1.
EVAPORATOR COIL SENSOR TEMPERATURE. If
the unit will not defrost, ensure that the evaporator coil
sensor temperature is actually below 7.2° C (45° F).
2.
MANUAL DEFROST AND DEF WIRE. If the unit
will not defrost, no alarm signal is displayed and the
evaporator return air temperature is below 7.2° C (45°
F, place a jumper wire from the DEF wire to the 8 wire
at the manual defrost switch. If the unit shifts to
DEFROST, the manual defrost switch is defective.
Replace the defective switch.
CAUTION: Remove jumper wires from the unit
after checking or testing unit components.
3.
EVAPORATOR COIL SENSOR. If the evaporator coil
sensor fails, the alarm light will flash and the micropro-
cessor will not initiate a defrost cycle. A faulty evapo-
rator coil sensor is reported on the fault indication
readout display as code 02 (evaporator coil sensor),
when the CODE key is depressed.
If the unit fails to defrost and coil sensor fault 02
occurs, check the evaporator coil sensor voltage to
determine if the sensor is faulty.
4.
MICROPROCESSOR. If the evaporator coil sensor is
good and the fault indication readout displayed code
02, the microprocessor is defective and should be
replaced.
Defrost Terminated On Time Limit
If the unit shifts to DEFROST but the evaporator tempera-
ture fails to rise, the defrost timer in the microprocessor will
automatically terminate defrost after 30 or 45 minutes. If the
evaporator temperature fails to rise, proceed to step 1 below.
1.
EVAPORATOR COIL TEMPERATURE. If the unit
will not come out of DEFROST, check to see if the
evaporator temperature is above 13.9° C (57° F). Use a
test thermometer to check the temperature. If the evap-
orator temperature does not rise enough to bring the
unit out of defrost, the condenser seal in the three-way
valve may be leaking, or the unit may be low on refrig-
erant.
To check the condenser seal in the three-way valve or
the condenser check valve, refer to the procedures
described in “Diagnosing TK Refrigeration System
(TK 5984).”
2.
Check the 26 circuit and the pilot solenoid.
3.
Check the damper relay, the 29 circuit and the damper
solenoid.
4.
FAULT INDICATION CODES. If the interval timer
terminates defrost, depress the CODE key to view and
write down any additional faults.
Summary of Contents for Super II SR+
Page 4: ......
Page 10: ...ii ...
Page 14: ...4 ...
Page 22: ...Unit Description Rev 6 98 12 Front View AEA1350 ...
Page 23: ...Unit Description Rev 6 98 13 Right Side Door Open AEA1351 ...
Page 24: ...Unit Description Rev 6 98 14 Left Side Doors Open AEA1352 ...
Page 26: ...Operating Instructions Rev 6 98 16 Control Box Cover AEA1354 ...
Page 34: ...24 ...
Page 42: ...Electronic Controls Rev 6 98 32 SOFTWARE REVISION 04XX ALARMS AEA1358 ...
Page 82: ...72 ...
Page 90: ...80 ...
Page 116: ...106 ...
Page 120: ...110 ...
Page 130: ...120 ...
Page 141: ...131 Schematic Diagram SBIII SII RMNII 30 SR MPIV ...
Page 142: ...132 Wiring Diagram SII SBIII RMN30 SR MPIV Page 1 of 4 ...
Page 143: ...133 Wiring Diagram SII SBIII RMN30 SR MPIV Page 2 of 4 ...
Page 144: ...134 Wiring Diagram SII SBIII RMN30 SR MPIV Page 3 of 4 ...
Page 145: ...135 Wiring Diagram SII SBIII RMN30 SR MPIV page 4 of 4 ...