Carrier 38GNA - Manual (Page 5)

For continued high performance and to minimize possible equip­
ment failure, periodic maintenance is essential. Consult dealer for
proper maintenance frequency and availability of a maintenance
contract.
Air for unit is drawn into front of unit at the bottom, and
discharged out same side at the top. Keep air inlet and outlet
louvers unplugged and clear of any obstructions at all times. Never
cover unit or lean anything against it which might restrict airflow
or cause hot air from upper louvers to recirculate into lower
louvers. Keep trash and debris away from unit. Never stand on unit
or use it as a support for ladders, etc.
Refrigerant tubing is easily crushed or crimped, therefore, do not
hang or stand anything on it. Do not move unit after it has been
installed, as this may crimp tubing and cause unit to malfunction.
The ability to properly perform maintenance on this equipment
requires certain mechanical skills and tools. If you do not possess
these, contact dealer for maintenance.
A WARNING
System contains oil and refrigerant under pressure. Do not use
a torch when disconnecting refrigerant components. Wear
safety goggles.
To disconnect refrigerant components;
1. Turn off electrical power to unit.
2. Recover refrigerant from unit.
3. Cut component connecting tubing with tubing cutter and
remove component from unit.
4. Carefully unsweat tubing stubs from component. Oil may
ignite when exposed to torch flame.
Step 1—Blower Wheel and Motor Removal
The blower assembly may easily be removed through the rear
access panel in the following manner:
1. Shut off all power to the unit.
2. Loosen and remove 3 screws holding the rear access panel in
place and remove rear access panel from unit. (See Fig. 7.)
3. Disconnect the 2 electrical leads from the blower motor to the
compressor contactor.
4. Remove screws at top right and top left of blower retaining
panel.
5. Remove entire blower assembly by lowering rear of assembly
and lifting it toward you, so as to disengage it from slots in
angles attached to sides of casing. Entire assembly can be
removed through rear of unit.
NOTE: Assembly must be supported when screws are removed.
6. To change motor or wheel, loosen wheel setscrews with
wrench. Remove 2 screws from blower housings. Remove 2
motor clamps and free assembly from panel.
7. Slide wheel and scroll from motor shaft.
8. Remove wheel from blower housing by removing 2 screws at
top of scroll outlet and pushing wheel through outlet.
9. Reassemble in reverse procedure. Be sure blower wheel is
centered in housings before entire blower panel assembly is
placed back in the unit.
10. Connect the 2 electrical leads from the blower to the com­
pressor contactor.
11. Replace the rear access panel and tighten the 3 screws.
12. Turn on power to unit.
A88548
Fig. 7—Rear Access Panel Removed
Step 2—Electrical Controls and Wiring
Disconnect power to unit. Check all electrical connections for
tightness. Tighten all screws on electrical connections. If any
smoky or burned connections are observed, disassemble the
connection(s), clean all parts, strip wire, reassemble properly (use
new connector if old one is burned or corroded), and secure tightly.
Electrical controls are difficult to check without proper instru­
ments. Therefore, reconnect electrical power to unit and observe it
through a complete operating cycle. If there are any performance
problems in operating cycle, correct them.
Step 3—Refrigerant Circuit
This circuit is difficult to check for leaks without proper equip­
ment. Therefore, if low cooling performance is suspected, dealer
service is required.
Step 4—Compressor Protection
The 018 size unit is equipped with a reciprocating compressor,
while the 024 size has a scroll compressor. In both applications
the compressor motor is protected by an internal current and
temperature-sensitive overload. Excessive current or temperature
causes internal overload to open, giving the indication of an open
circuit in the motor windings. The overload resets automatically
when internal motor temperatures drop to a safe level (overloads
may require up to 30 minutes to reset). When an internal overload
is suspected of being open, check by using an ohmmeter or
continuity tester.
The scroll compressor is equipped with a low-voltage dome
thermostat that will interrupt low-voltage power to the contactor.
The 024 size has time-delay relay (TDR) as standard equipment to
ensure against short cycling which can cause reverse rotation on
shutdown.
Step 5—Compressor Removal
Follow safety codes, and wear safety glasses and work gloves.
Have quenching cloth available for Step 7 below.
1. Shut off power to unit. Remove rear access panel.