Operating instructions

TM 11574A-OI
3-9
(c) Removing the Manifold Gauge Set if performed following the steps below:
1
While the compressor is still ON, open (backseat) the high side service valve.
2
Mid seat both hand valves on the manifold gauge set and allow the pressure in the
manifold gauge set to be drawn down to suction pressure. This returns any liquid
that may be in the high side hose to the system.
3
Open (backseat) the suction service valve. Open (backseat) both field service
couplings and front seat both manifold set valves. Remove the couplings from the
service ports.
4
Install both service valve stem caps and service port caps (finger-tight only).
(d) Pumping the unit down. To service the filter-drier, moisture-liquid indicator, expansion
valve, suction modulation valve, quench valve, or evaporator coil, pump the refrigerant
into the high side as follows:
1
Attach manifold gauge set to compressor service valves (refer to Manifold gauge set
paragraph 3-10b(2)).
2
Start the unit and run in a cooling mode for 10 to 15 minutes. Front seat the liquid line
service valve. Place start-stop switch in the OFF position when the suction reaches a
positive pressure of 1.0 psig@ (0.1 kg/cm).
3
Front seat (fully closed) the suction service valve. The refrigerant will be trapped
between the compressor suction service valve and the liquid line valve.
4
Before opening up any part of the system, a slight positive pressure should be
indicated on the pressure gauge. If a vacuum is indicated, emit refrigerant by
cracking the liquid line valve momentarily to build up a slight positive pressure.
5
When opening up the refrigerant system, certain parts may frost. Allow the part to
warm to ambient temperature before dismantling. This avoids internal condensation,
which puts moisture in the system.
6
After repairs have been made, be sure to perform a refrigerant leak check (refer to
Refrigerant leak check paragraph 3-10b(2)(e)), and evacuate and dehydrate the low
side (refer to Evacuation and dehydration paragraph 3-10b(3)).
7
Check refrigerant charge (refer to Refrigeration charge paragraph 3-10b(4)).