Carrier BT30RF- EXPR Service & Installation Manual page 43

COMPRESSOR INSTALLATION & MAINTENANCE
TO CHANGE THE COMPRESSOR:
1. Disconnect the power supply to the cabinet.
2. Disconnect the power supply leads at the
compressor.
3. Disconnect wires to relay and capacitors.
4. Remove relay and starting capacitor and install on
new compressor.
5. Remove defective compressor from condensing
unit base.
6. Set new compressor in place.
7. Reconnect relay and capacitor wires.
8. Reconnect power supply lead.
9. Leak test, evacuate, and weigh in charge.
CHANGING DRIER
If flare connected, make sure flares and faces of fit-
tings on new drier are clean and in good condition
before installing new drier.
If sweat connected, clean tubing close to original
drier before cutting tubing in clean area. Check that
ends of the replacement drier are clean, then make
brazed connection using as little heat as possible.
Cut tubing only with tube cutters, not hacksaws, to
avoid metal filings from entering the system. Driers
must be replaced any time you enter the system,
except when you are obtaining pressures.
SERVICE VALVES
The compressors on some cabinets have service
valves for measuring suction and discharge pressures.
Two types are used. The first type is connected direct-
ly to the compressor body or shell and back seats to
connect gauges to the access port. The second is on
the end of a process tube and requires a gauge or
charging line with a depressing pin to open valve when
the connection is made.
This type valve should be tightly
CAUTION:
capped except when making the
gauge connection.
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TO CHECK FOR OPEN WINDINGS
Use a multimeter. Measure ohms between "C" and "R"
and between "C" and "S."
If windings are O.K., multimeter will show a resistance
reading between terminals.
If there is no reading, the compressor winding or
windings are open and the compressor should be
replaced.
TO CHECK FOR GROUNDED COMPRESSOR
Use multimeter. Touch probe from each terminal to an
unpainted surface of compressor body. If there is no
ground, there will be no change of the meter.
WARNING: Be Careful Not to Touch
Uninsulated Parts of the Meter Probes
A reading indicates a ground and the compressor
should be replaced.
If there is voltage at the compressor terminals and the
compressor tries, but does not run, check voltage at
the compressor terminals while attempting to start the
compressor. If the voltage at the compressor terminals
is below 90% of the nameplate voltage, it is possible
the motor may not have developed sufficient torque to
start. Check to determine if:
A. Wire sizes are adequate.
B. Electrical connections are tight.
C. The circuit is not overloaded.
D. The power supply is adequate.
A defective relay or capacitor may prevent the com-
pressor starting.
TO CHECK OUT THE RELAY
1. Disconnect the cabinet from the power supply.
2. Remove the wires from the relay.
3. Touch probes to the contact terminals. Meter
should show infinity if closed.
4. Touch probes to the terminals of coil. The meter
should show a resistance reading.
If items 3 and 4 are O.K., the relay is good. If items 3
and 4 are not as indicated, change the relay.
MAINTENANCE & REPAIR