Carrier 30HXC Series Installation, Operation And Maintenance Instructions page 31

To minimize the opportunity for reverse rotation, the following
procedure must be applied. Rewire the power cables to the
compressor terminal pin as originally wired.
For replacement of the compressor, a low pressure switch is
included with the compressor. This low pressure switch should
be temporarily installed as a hard safety on the high pressure
part of the compressor. The purpose of this switch is to protect
the compressor against any wiring errors at the compressor
terminal pin. The electrical contact of the switch would be
wired in series with the high pressure switch. The switch will
remain in place until the compressor has been started and
direction of rotation has been verified; at this point, the switch
will be removed.
The switch that has been selected for detecting reverse rotation
is Carrier part number HK01CB001. It is available as part of
the "Compressor installation package" (part No. 06NA 660
013). This switch opens the contacts when the pressure falls
below 50 mm of vacuum. The switch is a manual reset type
that can be reset after the pressure has once again risen above
70 kPa. It is critical that the switch be a manual reset type to
preclude the compressor from short cycling in the reverse
direction.
15.8.2 - EXD Troubleshooting Procedure
Follow steps below to diagnose and correct EXD/
Economizer problems.
On 30HXC/GX units with economizers, verify that the valve
for the bubbler tube (bottom of Economizer) is open. Check
EXD motor operation first (see procedure in the Controls
IOM). You should be able to feel the actuator moving by
placing your hand on the EXD or economizer body (the
actuator is located about one-half to two-thirds of the way up
from the bottom of the economizer shell). You should feel a
hard knocking come from the actuator when it reaches the top
of its stroke (can be heard if surroundings are relatively quiet).
The actuator should knock when it reaches the bottom of its
stroke. If it is believed that the valve is not working properly,
contact your Carrier service department for further checks on:
• output signals on EXD module
• wire connections (continuity and tight connection at all pin
terminals)
• resistance of the EXD motor windings.
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