Carrier 69NT40-561-300, Operation And Service Manual

Page: 122 / 174

T-365 7–6
7.6.3 Complete System
NOTICE
Refer to Partial System procedure for information pertaining to partial system evacuation and
dehydration.
1. Remove all refrigerant using a refrigerant recovery system.
2. The recommended method to evacuate and dehydrate the system is to connect evacuation hoses at the
compressor discharge and suction and liquid line service valve (see Figure 7.4 ). Be sure the service hoses
are suited for evacuation purposes.
NOTICE
To prevent the area between the Economizer Solenoid Valve (ESV) and the Compressor from
being isolated during evacuation, it is necessary to open the ESV using a magnet tool, Carrier
Transicold part number 07-00512-00.
To prevent the area between the DUV and the Compressor from being isolated during evacua-
tion, it is necessary to open the DUV using a magnet tool, Carrier Transicold part number 07-
00512-00.
3. Remove the ESV and DUV coils from the valve bodies. Place the magnet tool over the valve stem, an audi-
ble click will be heard when the ESV opens.
NOTICE
Make sure to replace the valve coils before restating the unit. Starting the unit with the coil
removed from the valve will burn out the coil.
4. Test the evacuation setup for leaks by backseating the unit service valves and drawing a deep vacuum with
the vacuum pump and gauge valves open. Shut off the pump and check to see if the vacuum holds. Repair
leaks if necessary.
5. Midseat the refrigerant system service valves.
6. Open the vacuum pump and electronic vacuum gauge valves, if they are not already open. Start the vacuum
pump. Evacuate unit until the electronic vacuum gauge indicates 2000 microns. Close the electronic vacuum
gauge and vacuum pump valves. Shut off the vacuum pump. Wait a few minutes to be sure the vacuum holds.
7. Break the vacuum with either clean dry refrigerant 134a or dry nitrogen. Raise system pressure to roughly
0.14 bar (2 psig), monitoring it with the compound gauge.
8. If R134a was used, remove refrigerant using a refrigerant recovery system. If nitrogen was used, relieve the
pressure.
9. Repeat steps 6 and 7 one time.
10.Remove the copper tubing and change the filter drier. Evacuate unit to 500 microns. Close the electronic
vacuum gauge and vacuum pump valves. Shut off the vacuum pump. Wait five minutes to see if vacuum
holds. This procedure checks for residual moisture and/or leaks.
11. With a vacuum still in the unit, the refrigerant charge may be drawn into the system from a refrigerant con-
tainer on weight scales.
7.6.4 Partial System
1. If refrigerant charge has been removed from the low side only, evacuate the low side by connecting the
evacuation set-up at the compressor suction valve and the liquid service valve but leave the service valves
frontseated until evacuation is completed.
2. Once evacuation has been completed and the pump has been isolated, fully backseat the service valves to
isolate the service connections and then continue with checking and, if required, adding refrigerant in accor-
dance with normal procedures.