Trane CXAO Installation Operation & Maintenance page 46

Refrigerant replacement procedure
WARNING! The symptoms of a low refrigerant charge
are:
• Low evaporation pressure
• High superheat the intake and exhaust (outside
the above limits)
• Low value of subcooling.
In this case, add refrigerant R134a in the corresponding
circuit. The system is planned charging port between the
expansion valve and the evaporator. Charge refrigerant
until conditions return to work normal.
Remember to replace the cap closing the valve at the
end.
If the unit has not been provided with integrated pump
on board, do not turn off the external pump before You
do not 3 minutes have elapsed after turning off the last
compressor. The early shutdown of the pump Causes a
water fl ow alarm failure.
Seasonal shutdown
1. Turn switches Q1 and Q2 to the Off (or 0) position
to shut down the compressors, using the normal
pumpdown procedure.
2. After the compressors have been shut down, turn
switch Q0 to Off (or 0) and wait for the built-in water
pump to shut down. If the water pump is managed
externally, wait for 3 minutes after the compressors
have shut down before turning off the pump.
3. Open the Q12 (Off position) thermal magnetic switch
inside the control section of the electrical board then
open the general disconnect switch Q10 to cut off the
unit's power supply entirely.
4. Close the compressor intake taps (if any) and delivery
taps and also the taps located on the liquid and liquid
injection line.
5. Place a WARNING! sign on every switch that has been
opened, advising to open all the taps before starting
the compressors.
6. If no water and glycole mixture has been introduced
into the system, discharge all the water from the
evaporator and from the connected piping if the unit
is to remain inactive during the winter season. One
must remember that once the unit's power supply has
been cut off, the antifreeze electrical resistance cannot
function. Do not leave the evaporator and piping
exposed to the atmosphere during the entire period of
inactivity.
Starting up after seasonal shutdown
1. With the general disconnect switch open, make sure
that all the electrical connections, cables, terminals
and screws are well tightened to ensure good electrical
contact.
2. Verify that the power supply voltage applied to the unit
is within +/- 10% of the nominal nameplate voltage and
that the voltage unbalance between phases is between
+/- 3%.
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3. Verify that all control apparatus is in good condition
and functioning and that there is a suitable thermal
load for startup.
4. Verify that all the connection valves are well tightened
and that there are no refrigerant leaks. Always
reposition the valve caps.
5. Verify that switches are in the open position (Off).
Turn the general disconnect switch to the On
position. Doing this will allow to turn on the electrical
resistances of the compressors. Wait at least 12 hours
for them to start up.
6. Open all intake, delivery, liquid and liquid injection
taps. Always reposition tap covers.
7. Open the water valves to fi ll the system and bleed air
from the evaporator through the air valve installed on
its shell.
Verify that there are is no water leakage from piping.
RF-SVX003A-GB