![background image](http://html1.mh-extra.com/html/carrier/38au/38au_installation-start-up-and-service-instructions-manual_2560535035.webp)
35
Compressor Protection
COMPRESSOR OVER-TEMPERATURE PROTECTION (IP)
A thermostat installed on the compressor motor winding reacts
to excessively high winding temperatures and shuts off the
compressor.
CRANKCASE HEATER
The heater minimizes absorption of liquid refrigerant by oil in the
crankcase during brief or extended shutdown periods. The heater
is wired to cycle with the compressor; the heater is off when com-
pressor is running, and on when compressor is off.
The crankcase heater will operate as long as the power circuit is
energized. The main disconnect must be on to energize the crank-
case heater.
ADVANCED SCROLL TEMPERATURE PROTECTION
(ASTP)
See “Advanced Scroll Temperature Protection (ASTP)” on
page 21.
LOW-PRESSURE SWITCH
The 38AU low-pressure switch is stem-mounted on the suction
line. Switches are all fixed, non-adjustable type.
HIGH-PRESSURE SWITCH
The high-pressure switch is stem mounted on the discharge line.
The switch is a fixed, non-adjustable type.
OUTDOOR FANS
Each fan is supported by a formed-wire mount bolted to the fan
deck and covered with a wire guard. Fan motors have permanently
lubricated bearings.
1. Shut off unit power supply. Install lockout tag.
2. Remove outdoor fan assembly (grille, motor, and fan).
3. Loosen fan hub setscrews.
4. Adjust fan height as shown in Fig. 38.
5. Tighten setscrews to 84 in.-lbs (949 N-cm).
6. Replace outdoor fan assembly.
Fig. 38 — Outdoor Fan Blade Position
LUBRICATION
Fan Motors
The fan motors have sealed bearings. No provisions are made for
lubrication.
Compressor
The compressor has its own oil supply. Loss of oil due to a leak in
the system should be the only reason for adding oil after the sys-
tem has been in operation.
ROUTINE CLEANING OF ROUND-TUBE PLATE FIN
(RTPF) COILS
Periodic cleaning with Totaline
®
environmentally sound coil
cleaner is essential to extend the life of RTPF coils. This cleaner is
available from Carrier Replacement parts division as part number
P902-0301 for a one gallon container, and part number P902-0305
for a 5 gallon container. It is recommended that all RTPF coils be
cleaned with the Totaline environmentally sound coil cleaner as
described below.
Coil cleaning should be part of the unit’s regularly scheduled
maintenance procedures to ensure long life of the coil. Failure to
clean the coils may result in reduced durability in the environment.
Avoid the use of:
• coil brighteners
• acid cleaning prior to painting
• high pressure washers
• poor quality water for cleaning
Totaline environmentally sound coil cleaner is non-flammable,
hypoallergenic, non-bacterial, and a USDA accepted biodegrad-
able agent that will not harm the coil or surrounding components
such as electrical wiring, painted metal surfaces, or insulation. Use
of non-recommended coil cleaners is strongly discouraged since
coil and unit durability could be affected.
TOTALINE ENVIRONMENTALLY SOUND COIL
CLEANER APPLICATION EQUIPMENT
• 2
1
/
2
gallon garden sprayer
• water rinse with low velocity spray nozzle
Totaline Environmentally Sound Coil Cleaner Application
Instructions:
NOTE: Proper eye protection such as safety glasses is recom-
mended during mixing and application.
1. Turn off unit power.
2. Remove screws holding rear corner post and top cover in
place. Pivot top cover up 12 to 18 inches (305 to 457 mm)
and support with a rigid support. See Fig. 39.
IMPORTANT: Never open any switch or disconnect that ener-
gizes the crankcase heater unless unit is being serviced or is to
be shut down for a prolonged period. After a prolonged shut-
down on a service job, energize the crankcase heater for 24
hours before starting the compressor.
3.6 mm +0/0/-0.8
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in accelerated corro-
sion of unit parts.
Harsh chemicals, household bleach or acid or basic cleaners
should not be used to clean outdoor or indoor coils of any kind.
These cleaners can be very difficult to rinse out of the coil and
can accelerate corrosion at the fin/tube interface where dissim-
ilar materials are in contact. If there is dirt below the surface of
the coil, use the environmentally balanced coil cleaner.
IMPORTANT: High velocity water from a pressure washer,
garden hose, or compressed air should never be used to
clean a coil. The force of the water or air jet will bend the
fin edges and increase airside pressure drop, resulting in
reduced unit performance.