Board Components And Specifications; Service; General; Motor/Blower Assembly - Carrier 42C Series Installation Instructions Manual

Board Components and Specifications

Before proper control operation can be verified, all other systems
must be operating properly. The correct water and air temperatures
must be present for the control function being tested. Some con-
trols and features are designed to not operate under certain condi-
tions. For example, on a two-pipe cooling/heating system with
auxiliary electric heat, the electric heater cannot be energized with
hot water in the system.
A wide range of controls, electrical options and accessories may
be used with the equipment covered in this manual. Consult the
approved unit submittals, order acknowledgments, and other liter-
ature for detailed information regarding each individual unit and
its controls. Since controls and features may vary from one unit to
another, care should be taken to identify the controls used on each
unit and their proper control sequence. Information provided by
component manufacturers regarding installation, operation, and
maintenance of their individual controls is available upon request.
When changing from one mode to another (cooling to heating or
heating to cooling), it may take some time to actually notice a
change in the leaving air temperature. In addition, some units may
be designed for a very low air temperature rise in heating. Before
declaring a unit inoperative or a component defective, it may be
necessary to verify operation by more than one method.

SERVICE

General

Each unit on a job will have its own unique operating environment
and conditions which may dictate a maintenance schedule for that
unit that is different from other equipment on the job. A formal
schedule of regular maintenance and an individual unit log should
be established and maintained. This will help to achieve the maxi-
mum performance and service life of each unit on the job.
IMPORTANT: Information regarding safety precautions con-
tained at the beginning of this manual should be followed during
any service and maintenance operations.
For more detailed information concerning service operations con-
sult your Sales Representative or the factory.

Motor/Blower Assembly

The type of fan operation is determined by the control components
and their method of wiring. This may vary from unit to unit. Refer
to the wiring diagram that is attached to each unit for that unit's in-
dividual operating characteristics.
All motors have permanently lubricated bearings. No field lubri-
cation is required.
Should the assembly require more extensive service, the motor/
blower assembly may be removed from the unit to facilitate such
operations as motor or blower wheel/ housing replacement, etc.
Dirt and dust should not be allowed to accumulate on the blower
wheel or housing. This can result in an unbalanced blower wheel
condition which can damage a blower wheel or motor. The wheel
and housing may be cleaned periodically using a vacuum cleaner
and a brush taking care not to dislodge the factory balancing
weights on the blower wheel blades.

To Clean Coil

Coils may be cleaned by removing the motor/blower assemblies
and brushing the entering air face between fins with a stiff brush.
Brushing should be followed by cleaning with a vacuum cleaner.
If a compressed air source is available, the coil may also be
cleaned by blowing air through the coil fins from the leaving air
face. This should again be followed by vacuuming. Units provided
with the proper type of air filters, replaced regularly, will require
less frequent coil cleaning.
1. Be sure electrical service switch is open, locked, and
tagged while working on unit.
2. Remove return-air grille access panel and brush between
coil fins with stiff wire brush. Care should be taken to not
damage coil fins. Follow-up by cleaning with vacuum
cleaner. If coil is cleaned with air hose and nozzle, take
care not to drive dirt and dust into other components. Blow
air through the coil fins from the leaving air face. This
should again be followed by vacuuming. Units
with the proper type of air filters, replaced regularly, will
require less frequent coil cleaning.
3. Install clean filter. Refer to Filters, Throwaway or Filters,
Permanent section for proper filter changing on page 81.

Drain

The drain should be checked before initial start-up, and at the be-
ginning of each cooling season to assure that the drain, drain trap,
and line are clear. If it is clogged, steps should be taken to clear the
debris so that condensate will flow easily.
Periodic checks of the drain should be made during the cooling
season to maintain a free-flowing condensate. Units provided with
a secondary or "tell-tale" drain connection will indicate a clogged
main-drain line by flow from the "tell-tale" connection.
Should the growth of algae and/or bacteria be a concern, consult
an air conditioning and refrigeration supply organization familiar
with local conditions for chemicals, or other solutions available to
control these agents.

Electric Heater Assembly

Electric heaters typically require no normal periodic maintenance
when unit air filters are changed properly. The operation and ser-
vice life may be affected by other conditions and equipment in the
system. The two most important operating conditions for an elec-
tric heater are proper air flow and proper supply voltage. High
supply voltage and/or poorly distributed or insufficient air flow
over the element will result in element overheating. This condition
may result in the heater cycling on the high limit thermal cutout.
Sheath heaters have automatic reset switches only. Open-strip
heaters have an automatic reset switch with a back-up, high-limit
thermal switch.
Automatic reset switches reset automatically after the heater has
cooled down. High-limit thermal switches must be replaced once
the circuit has been broken. The high-limit thermal cutout device
is a safety device only, and is not intended for continuous opera-
tion. With proper unit application and operation, the high-limit
thermal cutout will not operate. This device only operates when a
problem exists, and ANY condition that causes high-limit cutout
MUST be corrected immediately. High supply voltage also causes
excessive amperage draw and may trip the circuit breaker or blow
the fuses on the incoming power supply.
After proper air flow and supply power are assured, regular filter
maintenance is important to provide clean air over the heater. Dirt
that is allowed to deposit on the heating element will cause hot
spots and eventual element burn through. These hot spots will nor-
mally not be enough to trip the high-limit thermal cut-out device,
and may not be evident until actual heater element failure.

TYPICAL HEATER TYPES

Refer to Fig. 88 for wire representation.
1. Exposed wire heater for 42CA, CE, CK, and CG.
2. Exposed wire heater for 42DD.
80
provided