Allied Air Enterprises 4AC16LT - Manual (Page 8)

506467-01 Issue 1008
(It may be necessary to bypass the low pressure switches
to ensure complete refrigerant evacuation.)
When the low side system pressures reach 0 psig, close
the suction line valve. Disconnect all power to the existing
outdoor unit. Refer to the gauges after shutdown to confirm
that the valves are not allowing refrigerant to flow back into
the low side of the system. Disconnect the liquid and suction
lines from the existing outdoor unit.
2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure outlined
previously on this page to make line set connections. Do
not install the R410A thermal expansion valve at this
time.
3. Make low voltage and line voltage connections to the
new outdoor unit. Do not turn on power to the unit or
open the outdoor unit service valves at this time.
4. Remover the existing R-22 refrigerant flow control orifice
or thermal expansion valve before continuing with flushing
procedures. R-22 flow control devices are not approved for
use with R410A refrigerant and may prevent proper flushing.
Use a field-provided fitting to reconnect the lines.
5. Remove the pressure tap valve cores from the 4AC16LT
units service valves. Connect an R-22 cylinder with clean
refrigerant to the suction service valve. Connect the R-22
gauge set to the liquid line valve and connect a recovery
maching with an empty recovery tank to the gauge set.
6. Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to allow
the recovery machine to pull a vacuum on the existing system
line set and indoor coil.
7. Invert the cylinder of clean R-22 and open its valve to
allow liquid refrigerant to flow in to the system through the
suction line valve. Allow the refrigerant to pass from the
cylinder and through the line set and the indoor coil before it
enters the recovery machine.
8. After all of the liquid refrigerant has been recovered, switch
the recovery machine to vapor recovery so that all of the R-
22 vapor is recovered. Allow the recovery machine to pull a
vacuum on the sytem.
NOTE: A single system flush should remove all of the mineral
oil from the existing refrigerant lines and indoor coil. A second
flushing may be done (using clean refrigerant) if insufficient
amounts of mineral oil were removed during the first flush.
After each system flush, allow the recovery machine to
pull a vacuum on the system at the end of the procedure.
9. Close the valve on the inverted R-22 cylinder and the
gauge set valves. Pump the remaining refrigerant out of
the recovery machine and turn the machine off.
10. Use nitrogen to break the vacuum on the refrigerant
lines and indoor coil before removing the recovery machine,
gauges, and R-22 refrigerant drum. Re-install pressure tap
valve cores into the 4AC16LT unit’s service valves.
11. Install the refrigerant expansion valve approved for use
with R410A refrigerant in the liquid line at the indoor coil.
Refrigerant Metering Device
4AC16LT units are designed for use with TXV systems only.
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.
To install an expansion valve (See Figure 9 above):
1. Separate the distributor assembly and remove the piston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributor and tighten to 20 - 30 ft. lbs. Use backup wrench
on all wrench flats. Overtightening will crush the teflon
seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench
flats. Overtightening will crush the teflon seal and may
cause a leak.
3. Connect the external equalizer line to the equalizer port
on the suction line and tighten to 8 ft.lbs.
4. Strap the superheat sensing bulb to the suction header.
If installing an expansion valve on an indoor coil that
previously used a fixed orifice, be sure to remove the existing
fixed orifice. Failure to remove a fixed orifice when installing
an expansion valve to the indoor coil will result in improper
operation and damage to the system.
Page 8
Table 3
TXV Data
MODEL PART NUMBER
4AC16LT -24, -36
4AC16LT -48
A4TXV01
A4TXV02
4AC16LT -60 A4TXV02