Refrigeration Maintenance
131
8. When the desired micron level has been
achieved (500 to 1000 microns), close valve
V-1 at the pump. Turn the pump off.
9. Observe the reading on the micron gauge after
5 minutes have elapsed. The vacuum rise
should not exceed 2000 microns. If the
vacuum level exceeds 2000 microns after
5 minutes, a leak is present or additional
evacuation time is required.
10. If the vacuum level is acceptable, start the
pump and open valve V-1 to evacuate the
pressure rise (5 minutes).
11. Close valve V-1 and stop the pump. Observe
the micron gauge to confirm that the system
remains in a deep vacuum. Close valve V-4.
The unit is ready to charge.
Unit Charging
NOTE: Before charging, make sure that the
refrigerant lines from the gauge manifold to the
refrigerant supply bottle have been evacuated or
purged.
1. Backseat the suction service valve and make
sure the receiver tank outlet valve is still open.
2. Set the refrigerant supply bottle to liquid and
open the hand valve.
3. Open the high side gauge manifold valve. Add
a partial charge of 10 lbs (4.5 kg) of liquid
refrigerant and close the high side gauge
manifold valve. The remainder of the charge
will be added as a liquid through the low side
gauge manifold valve.
4. Back seat (close) the receiver tank outlet
valve, remove the evacuation station hoses,
and install the cap on the service port for the
receiver tank outlet valve.
5. Attach the gauge manifold set to the suction
service valve and the discharge service port,
and open the suction service valve one turn. A
low loss fitting must be used on the hose
connected to the discharge service port.
6. Exit the Evacuation Mode by pressing the
EXIT key, and remove the battery charger.
7. Set all zones to run in High Speed Cool
through the HMI Service Test Mode. Refer to
the SPECTRUM TS Microprocessor
Diagnostic Manual (TK 51652) for
information about the Service Test Mode.
8. Observe the suction pressure and slowly open
the low side gauge manifold valve to allow
liquid refrigerant to flow into the compressor
suction service valve.
9. Control the liquid flow so the suction pressure
increases approximately 20 to 25 psig (138 to
172 kPa).
10. Maintain a discharge pressure of at least 300
psig (2068 kPa) while adding refrigerant.
11. Close the low side gauge value when the
receiver sight glass shows 1/2 to 3/4 full.
12. Establish a return air temperature of 0 F
(-18 C), a suction pressure of 13 to 18 psig (90
to 124 kPa), and a discharge pressure of 300
psig (2069). See See “Testing the Refrigerant
Charge with an Empty Box” on page 132.
13. Check the receiver tank sight glass. The
refrigerant level should remain between 1/2
and 3/4 full over a period of no less than five
minutes.
14. When the correct amount of charge has been
added, close the gauge manifold hand valve
and the refrigerant supply bottle hand valve.
NOTE: At these conditions the Liquid Injection
Valve will cycle on and off. As this happens the
refrigerant level in the receiver tank sight glass
will raise and lower. Therefore, monitoring the
receiver tank sight glass for a period of five
minutes to make sure that the average level of
the refrigerant over this five-minute period is
between 1/2 and 3/4 full is required.
Remove Refrigerant Hoses
NOTE: Low loss fittings must be used on hoses
when Schrader port fittings are encountered on
units.
1. With a low loss fitting on the discharge gauge
line, remove this line from the unit.
2. Backseat the suction service valve, and then
crack it open one turn.
To Next Page
Loading...
Need help?
General
