Carrier 50PM20 Installation Instructions Manual page 37

TUBES
STRAIGHTEDGE MUST
PARALLEL
WITH BELT
FINS
PULLEY
PULLEY
MOTOR AND FAN
SHAFTS MUST BE
PARALLEL SETSCREWS '_
FIXED FLANGE_
MOVABLE
FLANGES
SINGLE-GROOVE
MANIFOLD
MICROCHANNELS
Fig. 29 - Microchannel Coils
C07273
/
Repairing Tube Leaks /
II
RCD offers service repair kits for repairing tube leaks in the
crosstubes. These kits include approved braze materials and
instructions specific to the aluminum microchannel coil.
C08081
Fig. 27 - Evaporator-Fan Alignment and Adjustment
C07204
Fig. 28 - Condenser-Fan Adjustment
MCHX Condenser Service and Replacement
The condenser coil in this unit is a MicroChannel Heat Exchanger
(MCHX) surface. The MCHX is an all-aluminum construction
with fins over a single-depth crosstube. The crosstubes have
multiple small passages through which the refrigerant passes from
header to header on each end. (See Fig. 29.) The all-aluminum
construction provides increased resistance to corrosion over
aluminum fins on copper tubes in normal and mild marine
applications.
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
Use of other than approved repair procedures may affect the
pressure rating or the corrosion resistance of the microchannel
condenser coil,
Replacing the MCHX Coil
The service replacement coil is preformed and is equipped with
transition joints with copper stub tubes. When brazing the
connection joints to the unit tubing, use a wet cloth around the
aluminum tube at the transition joint. Avoid applying torch flame
directly onto the aluminum tubing.
Verify Sensor Performance
Using an ohmmeter and a thernmmeter, compare measured
temperature to the resistance shown in Table 10.
Economizer Operation During Power Failure
Dampers have a spring return. In event of power failure, dampers
will return to fully closed position until power is restored. Do not
manually operate damper motol:
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
Do not use MCHX coils in severe coastal or industrial
environments.
37