Section 3 - Maintenance And Service; Evaporator And Condenser Coils; Refrigerant Circuits; Blowers - Johnson Controls DSH024C Series Installation Operation & Maintenance

FORM 145.32-IOM5
ISSUE DATE: 08/30/2018
SECTION 3 – MAINTENANCE AND SERVICE
Disconnect and lock out power when
servicing unit. Failure to do so may result
in personal injury or death due to electri-
cal shock.
Exercise care when working around the
sharp metal edges of door panels or door
frames, etc. These edges can cause injury.

EVAPORATOR AND CONDENSER COILS

Inspect the evaporator coil at filter change intervals.
Inspect the condenser coil at least semi-annually. A
dirty condenser coil results in elevated condensing
pressures and poor unit performance. Dirty or clogged
evaporator coils cause low suction pressure and lost
capacity. If the coils appear dirty, clean them using a
mild detergent or a commercial coil cleaning agent.

REFRIGERANT CIRCUITS

During unit operation, check and record the com-
pressor discharge and suction pressures. Also record
the compressor running current. A maintenance log
of these readings can indicate if the unit is operating
within its normal limits. Investigate abnormal readings
and correct the cause.

BLOWERS

Inspect both the evaporator and condenser blowers at
each regular service interval. As required, clean the
blower wheels. Bearings are a permanently sealed ball
type and do not require lubrication. Check the bearings
for signs of wear (movement between the inner and outer
races). Ensure that the bearing locking collars are secure

FIGURE 20 - BELT TENSION ADJUSTMENT

to the shaft and that the collar locking screw is properly
set. Check that the blower wheel is tight on the shaft and
that the hub set screws are properly torqued.

DRIVE BELTS

Examine the belts periodically for wear. Glazed areas on
the drive surfaces indicate overheating due to belt slip-
page. The ideal tension is the lowest tension at which
the belt does not slip under peak load conditions. Over-
tensioning shortens the belt and bearing life (see Blower
Speed Adjustment on page 34).
Adjust the tension on the belt for a deflection of 1/64-
inch per inch of belt span, with the appropriate force
applied at the midpoint of the span. Tension new belts
at the maximum value indicated. Maintain used belts at
the minimum value.

FILTERS

Inspect the filters monthly and replace them as re-
quired. Use UL Class 2 rated filters. Factory supplied
filters are the medium efficiency, extended surface
pleated type. To maintain optimum airflow perfor-
mance, ensure the replacements are of the same type.
See Table 28 for filter sizes.

TABLE 28 - FILTER SIZES

Deflection 1/64-
inch per inch of
span length
FILTERS
DSH024C 2 / 25 x 14 x 2
DSH036C 2 / 25 x 14 x 2
DSH048C 2 / 25 x 16 x 2
DSH060C 2 / 25 x 16 x 2
DSH096C 4 / 20 x 16 x 2
DSH120C 4 / 20 x 16 x 2
POUNDS FORCE
CROSS
SECTION
MINIMUM
4L 1-1/2
A 3-1/2
B 5-1/2
BX 8
3
QTY/SIZE
MAXIMUM
2-1/2
6-1/2
8
11
LD27711
43