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73
Refrigeration Maintenance
REFRIGERANT CHARGE
Testing the Refrigerant Charge with an Empty
Trailer
If the unit has an insufficient charge of refrigerant, the evap-
orator will be “starved” and the box temperature will rise
even though the unit is operating. The suction pressure will
drop as the refrigerant charge decreases. If the unit has an
overcharge of refrigerant, the unit may not cool properly
and the suction and discharge pressure may be high. The
charge may be determined by inspection of the refrigerant
through the receiver tank sight glass with the following con-
ditions established:
1.
Place a test box over the evaporator.
2.
Install a gauge manifold.
3.
Use the Service Test Mode to run the unit in high speed
cool. Refer to the appropriate Operation and Diagnosis
Manual for specific information abut the Service Test
Mode.
4.
Use the microprocessor thermometer to monitor the
return air temperature.
5.
Run the unit on high speed cool until the air in the box
is at -18° C (0° F). By allowing the box to leak a small
amount, you will be able to maintain -18° C (0° F).
6.
The suction pressure should be 90 to 124 kPa
(13 to 18 psi).
7.
The discharge pressure should be at least 1896 kPa
(275 psi).
If the pressure is below this, it can be raised by cover-
ing a portion of the condenser grille with a piece of
cardboard to block condenser airfoil.
8.
Under these conditions, the ball should be floating in
the receiver tank sight glass.
Testing the Refrigerant Charge with a Loaded
Trailer
1.
Install a gauge manifold.
2.
Use the Service Test Mode to run the unit in high speed
cool. Refer to the appropriate Operation and Diagnosis
Manual for specific information abut the Service Test
Mode.
3.
Build up and maintain 1896 kPa (275 psi) of head pres-
sure. If the pressure is below this, it can be raised by
covering the left side condenser grille with a piece of
cardboard to block condenser air flow.
4.
Cool the compartment to the lowest temperature
required.
5.
Check suction pressure. It should be 90 to 172 kPa
(13 to 25 psi).
6.
Under these conditions, the ball should be floating in
the receiver tank sight glass.
Testing for an Overcharge
Use the following procedure to identify a Thermo King unit
with an excessive refrigerant charge:
1.
Install a calibrated gauge manifold on the compressor.
2.
Use the Service Test Mode to run the unit in high speed
cool. Refer to the appropriate Operation and Diagnosis
Manual for specific information abut the Service Test
Mode.
3.
Operate the unit in high speed cool long enough to sta-
bilize system pressures and reduce the box temperature
to approximately 16° C (60° F) or colder.
4.
Observe discharge pressure and cover the condenser to
increase the discharge pressure approximately 500 to
690 kPa (75 to 100 psi) above observed pressure.
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 ...
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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 ...