System Charging - Thermo King MD-200 MT Manual De Instalación

System Charging

IMPORTANT: Unit must be leak checked and fully evacuated before charging.
NOTE: Electrical controls must be set up as described in Electrical Controls
Set-up Section to start this procedure.
1. Install a gauge manifold. Attach low side to suction service valve, high side
to receiver outlet valve and discharge service valve.
2. Before charging system, make sure refrigerant lines from gauge manifold to
refrigerant supply bottle have been evacuated or purged, suction service
valve is back seated, and discharge service valve and receiver outlet valve
are mid-seated.
3. Set refrigerant supply bottle for liquid. Open gauge manifold hand valve and
add a partial charge of 4.1 kg (9.0 lb.) of R-404A. Do not add more than
this. Remainder of charge will be added through suction service valve while
unit is running.
4. Close gauge manifold hand valve.
5. Back seat receiver outlet valve and discharge service valve.
6. Mid-seat suction service valve.
7. Attach high pressure gauge on the gauge manifold to discharge service valve.
Mid-seat discharge service valve to monitor discharge pressure.
NOTE: Electrical controls must be returned back to factory settings (see
step 6).
8. Connect HGSA wire and RHGS wire to relay board. Connect condenser inlet
solenoid wires (2 pin connector) to main wire harness. Connect 20A wire to
low oil pressure switch. Replace CYCLE-SENTRY (orange) module if it
was removed from option board.
9. Start unit and operate both zones with thermostats set to cool.
10. Set both zone thermostats to their highest set point. If ambient is above set
point range jump power from the 2 circuit to HGS and RHGS to allow the
valves to open.
11. Set both zones for cool (remove jumpers if installed in previous step).
System Charging
12. Observe suction pressure and slowly open gauge manifold hand valve to
allow liquid refrigerant to flow into suction service valve. Control liquid
flow so suction pressure increases approximately 138 kPa (20 psi). Maintain
discharge pressure of at least 1896 kPa (275 psi).
13. Add refrigerant until ball in receiver sight glass rises to middle of sight glass,
then close gauge manifold hand valve. Make sure liquid level does not rise
above top of sight glass.
14. Continue to operate unit with evaporators in cool for 10 minutes. Check
position of ball in receiver sight glass. If liquid level has dropped, add liquid
refrigerant until level stabilizes near middle of sight glass.
15. Back seat discharge service valve.
Remove Refrigerant Hoses
1. Run unit with both zones in cool and receiver outlet and discharge service
valves back seated.
2. Front seat suction service valve. Allow compressor to pump down to 21 to
35 kPa (3 to 5 psi). Stop unit. Remove hose from suction service valve
service port. Immediately install cap on service port and tighten.
3. Back seat suction service valve.
4. Remove hoses from receiver outlet and discharge service valves.
5. Replace and tighten service port and valve stem caps.
A.
B.
C.
Legend for Evacuation and Charging Diagram below.
V–4 D. V–1
V–3 E. 2-Stage Vacuum Pump
V–2 F. To AC Power
Eng
G. Micron Gauge
H. Thermistor
I. Correct Refrigeration
Level
85