Energy Tech Laboratories DSH - Manual (Page 17)

FORM 145.32-IOM1 (908)
17
JOHNSON CONTROLS
MAINTENANCE / SERVICE
Disconnect And Lock Out Power When
Servicing Unit. Failure To Do So May
Result In Personal Injury Or Death Due
To Electrical Shock.
Exercise care when working around
the sharp metal edges of door panels
or door frames, etc. These edges can
cause injury.
FILTERS
Inspect filters monthly and replace as necessary. Use UL
Class 2 rated filters. Factory supplied filters are medium
efficiency, extended surface pleated type. Replacements
should be of the same type, to maintain optimum airflow
performance. Filter sizes are as follows:
DRIVE BELTS
Examine belts periodically for wear. Glazed areas on the
drive surfaces indicate overheating due to belt slippage.
Ideal tension is the lowest tension at which the belt will
not slip under peak load conditions. Over-tensioning
shortens belt and bearing life.
The tension on the belt should be adjusted for a deflec-
tion of 1164 of an inch per inch of belt span, with the ap-
propriate force applied at the midpoint of the span. Ten-
sion “New” belts at the maximum value indicated. Used
belts should be maintained at the minimum value.
REFRIGERANT CIRCUIT(S)
With the unit operating, check and record the compres-
sor discharge and suction pressures. The compressor
running current should also be recorded. A maintenance
log of these readings can indicate if the unit is operating
within its normal limits. Abnormal readings should be
investigated, and the cause corrected.
POUNDS FORCE
Belt Cross Section Min. Max.
4L 1-1/2 2-1/2
A 3-1/2 6-1/2
B 5-1/2 8
BX 8 11
POUNDS FORCE
Belt Cross Section Min. Max.
4L 1-1/2 2-1/2
A 3-1/2 6-1/2
B 5-1/2 8
BX 8 11
FILTERS 2 TON 3 TON
QTY / SIZE 2 / 20 x 14 x 2 2 / 20 x 14 x 2
FILTERS 4 TON 5 TON
QTY / SIZE 2 / 25 x 16 x 2 2 / 25 x 16 x 2
EVAPORATOR AND CONDENSER COILS
Inspect the evaporator coil at filter change intervals.
Inspect the condenser coil at least semi-annually. A
dirty condenser coil will result 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 mild
detergent or a commercial coil cleaning agent.
BLOWERS
Inspect both the evaporator and condenser blowers at
each regular service interval. Clean blower wheels as
needed. Bearings are permanently sealed ball type, and
do not require lubrication. Check bearings for any signs
of wear (movement between inner and outer races). En-
sure bearing locking collars are secure to the shaft, and
that collar locking screw is properly set. Check that the
blower wheel is tight on the shaft, and that the setscrews
in the blower hub are properly torqued.