Thermo King KD-II SR, Manual

Page: 114 / 182

Refrigeration Maintenance (Rev. 04/03)
100
Remove Evacuation Hoses
1. Run the unit in high speed cool with the receiver outlet
and discharge valves back seated.
2. Front seat the suction service valve and allow the com-
pressor to pump down to 3 to 5 psig (21 to 35 kPa).
Stop the unit. Remove the hose from the suction service
valve service port. Immediately install the cap on the
service port and tighten.
3. Back seat the suction service valve.
4. Remove the hoses from the receiver outlet and dis-
charge service valves.
5. Replace and tighten the service port and valve stem
caps.
6. The unit is ready for a functional check out and operat-
ing test of the refrigeration system.
REFRIGERANT LEAKS
Use a reliable leak detector (e.g., electronic detector) to leak
test the refrigeration system. Inspect for signs of oil leakage
which is the first sign of a leak in the refrigeration system.
NOTE: It is normal for compressor shaft seals to have a
slightly oily film.
REFRIGERANT CHARGE
Testing the Refrigerant Charge with an Empty Box
If the unit has an insufficient charge of refrigerant, the evap-
orator will be “starved” and the compartment temperature
will rise even though the unit is operating. The suction pres-
sure will drop as the refrigerant charge decreases. The
charge may be determined by inspection of the refrigeration
through the receiver tank sight glass with the following con-
ditions established:
1. Place a test box over the evaporator.
2. Place a thermometer (TK No. 204-135) test lead in the
box near the evaporator return air opening.
3. Install the gauge manifold.
4. Run the unit on Cool until the air in the box indicates 0 F
(-18 C). By allowing the box to leak a small amount,
you will be able to maintain 0 F (-18 C).
5. The ball in the receiver tank sight glass should be float-
ing under the conditions below:
a. Discharge Pressure Reading:
R-134a Systems—The discharge or head pressure
gauge should read 150 psig (1034 kPa).
R-404A Systems—The discharge or head pressure
gauge should read 275 psig (1900 kPa).
NOTE: If the pressure is below this, it can be
raised by covering a portion of the condenser coil
with a piece of cardboard.
b. Suction Pressure Reading:
R-134a Systems—The compound gauge should be
indicating 0 to 2-1/2 psig (0 to 17 kPa) gauge pres-
sure.
R-404A Systems—The compound gauge should
be indicating 13 to 18 psig (90 to 124 kPa) gauge
pressure.
NOTE: If there is any doubt about the unit
gauge, check the calibration.
Testing the Refrigerant Charge with a Loaded
Compartment
1. Install a gauge manifold (optional).
2. Run the unit on the Cool cycle.
3. Cover at least three quarters of the condenser to drive
any excess refrigerant from the condenser into the
receiver tank.