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POWER AND COOLING UNIT MANUAL EXTRACT
4.3.2
COOLING SYSTEM MAINTENANCE AIDS
4.3.2.1
AIR FLOW SENSOR SWITCH OPERATION
NOTE:
THE AIR FLOW SENSOR SWITCH IS NORMALLY CLOSED.
THE SWITCH OPENS WHEN THE BLOWER REACHES ITS NORMAL
OPERATING SPEED ABOUT 4-8 SECONDS AFTER INITIAL
STARTUP.
To check the operation of this switch proceed as follows:
NOTE:
THE AIR FLOW SENSOR SWITCHES ARE LOCATED AT QXNl and
XZNl ABOVE THE COOLING BLOWERS AT THE FRONT OF THE
CABINET.
1.
Remove switch cover.
2.
Remove COMMON (top) wire.
3.
Loosen NORMALLY OPEN (middle) screw.
4.
Set WOM to scale RXl and clip VOM to top and middle screws.
5.
Turn blower on and allow a few seconds for blower to
reach normal speed.
If VOM reads a short, the switch is
good; if VOM reads open, the switch is defective.
SWITCH COVER
A ISSUED
AIR FLOW SENSOR SWITCH
DWYER
26
161180-00
ASM. NO. 58020158
COVER FASTENING SCREW
SCALE -
run
NORMALLY
TO PCM
NORMALLY CLOSED
TO PCM
COMMON
~
- - a
,-}jc•
0
AIR FLOW SENSOR SWITCH
HONEYWELL CONFIDENTIAL AND PROPRIETARY
Figure 4-13
Sheet 7
44(F)
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