51
BRAZED-PLATE ECONOMIZERS — Brazed-plate econo-
mizers are factory-installed in each circuit on 30GXN,R108,
118-350 and 30HXA,C161-271 models. A TXV is included to
meter the flow of refrigerant to the economizer port of the
compressor. Flow through the TXV is enabled only when the
circuit is fully loaded for 30GXN,R models. The TXV bulb is
secured to the side of the economizer outlet tube. See Fig. 22
for typical piping arrangement.
Brazed-plate heat exchangers cannot be repaired if they de-
velop a leak. If a refrigerant leak is detected, the heat exchanger
must be
replaced. To replace a brazed-plate heat exchanger the
following steps must be performed:
1. Using proper techniques, move the refrigerant remaining
in the circuit to the high side and close the discharge and
liquid line ball valves. Reclaim any refrigerant remaining
in the low side.
2. Un-solder the refrigerant-in and refrigerant-out connections.
3. Remove the four 8mm (
1
/
4
-20 on 30HX units) nuts
holding the heat exchanger to the brackets. Save the nuts
and hardware.
4. Check that the replacement heat exchanger is the same as
the original heat exchanger.
5. Insulate the new heat exchanger to match the original and
attach to the mounting brackets with the hardware
removed in Step 3.
6.
Carefully
braze the refrigerant lines to the connections on
the heat exchanger. Lines should be soldered using silver
as the soldering material with a minimum of 45% silver.
Keep the temperature below 1472 F (800 C) under
normal soldering conditions (no vacuum) to prevent the
copper solder of the brazed plate heat exchanger from
changing its structure. Failure to do so can result in inter-
nal or external leakage at the connections which cannot
be repaired.
7. Braze equalizer line in place if removed. Attach econo-
mizer and motor cooling solenoid coils to their bodies if
removed.
8. Dehydrate and recharge the circuit. Check for leaks.
NOTE: The brazed-plate heat economizers are not serviceable.
If operating problems persist after economizer replacement,
they may be due to a bad liquid level sensor, suction pressure
transducer, discharge gas thermistor or intermittent connections
between the processor board terminals and EXV plug. Recheck
all wiring connections and voltage signals.
Other possible causes of improper refrigerant flow control
could be restrictions in the liquid line. Check for plugged
strainer(s) or restricted metering slots in the EXV (see Fig. 23).
Formation of ice or frost on lower body of electronic expansion
valve is one symptom of restricted metering slots. However,
frost or ice formation is normally expected when leaving fluid
temperature from the cooler is below 40 F (4.4 C). Clean or re-
place valve if necessary.
NOTE (non-economized units only): Frosting of valve is
normal during compressor test steps and at initial start-up.
Frost should dissipate after 5 to 10 minutes operation in a
system that is operating properly. If valve is to be replaced,
wrap valve with a wet cloth to prevent excessive heat from
damaging internal components.
EXV
COOLER
FEED
BRAZED
PLATE
ECONOMIZER
TXV
BULB
ECONOMIZER
TXV
EQUALIZER
LINE
MOTOR
COOLING
SOLENOID
TXV
SOLENOID
STRAIN RELIEF
MOTOR ASSEMBLY
SEAL CAP
SLEEVE
SIGHTGLASS
ORIFICE
Fig. 22 — Brazed-Plate Economizer
Torque Specifications
Fig. 23 — Typical 30GXN,GXR,HX EXV
ITEM
ft-lb
n-m
Sight Glass
15-25
20-34
Seal Cap
18-22
24-30
