Controls, Start-Up, Operation, Service and ... - Climayoreo

Routine cleaning of coil surfaces is essential to maintain
proper operation of the unit. Elimination of contamination and
removal of harmful residues will greatly increase the life of the
coil and extend the life of the unit. The following steps should
be taken to clean MCHX condenser coils:
1. Remove any foreign objects or debris attached to the core
face or trapped within the mounting frame and brackets.
2. Put on personal protective equipment including safety
glasses and/or face shield, waterproof clothing and
gloves. It is recommended to use full coverage clothing.
3. Start high pressure water sprayer and purge any soap or
industrial cleaners from sprayer before cleaning condenser
coils. Only clean potable water is authorized for cleaning
condenser coils.
4. Clean condenser face by spraying the core steady and
uniformly from top to bottom while directing the spray
straight toward the core. Do not exceed 900 psig or
30 degree angle. The nozzle must be at least 12 in. from
the core face. Reduce pressure and use caution to prevent
damage to air centers.
CAUTION
Excessive water pressure will fracture the braze between
air centers and refrigerant tubes.
CONDENSATE DRAIN — Check and clean each year at
start of cooling season. In winter, keep drains and traps dry.
FILTERS — Clean or replace at start of each heating and cooling
season, or more often if operating conditions require. Refer
to Installation Instructions for type and size.
1. Remove economizer outdoor-air filters from the hoods by
removing the filter retainers.
2. Clean filters with steam or hot water and mild detergent.
3. Reinstall filters in hoods after cleaning. Never replace
cleanable filters with throwaway filters.
OUTDOOR-AIR INLET SCREENS — Clean screens with
steam or hot water and a mild detergent. Do not use disposable
filters in place of screens.
Lubrication
FAN SHAFT BEARINGS — Lubricate fan shaft bearings at
least once a year with suitable bearing grease. Extended grease
lines are provided on pulley side of blower. Typical lubricants
are given below:
MANUFACTURER LUBRICANT
Texaco Regal AFB-2*
Mobil Mobilplex EP No. 1
Sunoco Prestige 42
Texaco Multifak 2
*Preferred lubricant because it contains rust and oxidation inhibitors.
FAN MOTOR BEARINGS — The condenser-fan and
evaporator-fan motors have sealed bearings so no field lubrication
is required.
DOOR HINGES — All door hinges should be lubricated at
least once a year.
Refrigerant Feed Components — Each refrigerant
circuit (2 per unit) has all the necessary refrigerant controls.
Thermostatic Expansion Valve (TXV) — On sizes
030 and 035, each circuit has one TXV. On sizes 040-100, each
circuit has 2 TXVs on which superheat may be adjusted if necessary.
Adjustment is not normally required or recommended.
The TXV is set to maintain 10 to 13 F superheat leaving the
evaporator coil. It controls the flow of refrigerant to the evaporator
coils.
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Refrigeration Circuits
LEAK TESTING — Units are shipped with a full operating
charge of R-410A (see unit nameplate). If there is no pressure
in the system, introduce enough nitrogen to search for the leak.
Repair the leak using good refrigeration practices. After leaks
are repaired, system must be evacuated and dehydrated
using methods described in GTAC II, Module 4, System
Dehydration.
REFRIGERANT CHARGE — Amount of refrigerant charge
is listed on unit nameplate. Refer to Carrier GTAC II; Module
5; Charging, Recovery, Recycling, and Reclamation section for
charging methods and procedures.
Unit panels must be in place when unit is operating during
charging procedure.
NOTE: Do not use recycled refrigerant as it may contain
contaminants.
NO CHARGE — Use standard evacuating techniques. After
evacuating system, weigh in the specified amount of refrigerant
from the unit nameplate.
LOW CHARGE COOLING — Due to the compact, all aluminum
design, microchannel heat exchangers will reduce
refrigerant charge and overall operating weight. As a result,
charging procedures for MCHX units require more accurate
measurement techniques. Charge should be added in small
increments. Using cooling charging charts provided (Fig. 52-
89), add or remove refrigerant until conditions of the chart are
met. As conditions get close to the point on the chart, add or
remove charge in 1 / 4 lb increments until complete. Ensure that
all fans are on and all compressors are running when using
charging charts.
To Use the Cooling Charging Chart — Use the outdoor air
temperature, saturated suction temperature and saturated condensing
temperature (available on the ComfortLink display),
and find the intersection point on the cooling charging chart. If
intersection point is above the line, carefully recover some of
the refrigerant. If intersection point is below the line, carefully
add refrigerant.
NOTE: Indoor-air cfm must be within normal operating range
of unit.
In order to determine which charging chart to use, the technician
can verify the evaporator configuration of the unit (High
Cap or Std Cap) by counting the number of rows on the installed
evaporator. Use Table 103 to identify the correct unit
configuration for refrigerant charging.
Units With Humidi-MiZer® Adaptive Dehumidification
System
NOTE: All circuits must be running in normal cooling
mode. Indoor airflow must be within specified air quantity
limits for cooling. All outdoor fans must be on and running at
normal speed.
Table 103 — Unit Capacity Type
UNIT SIZE NUMBER OF ROWS ON EVAPORATOR
48/50P
High Capacity Std Capacity
030 4 3
035 N/A 4
040 6 3
050 6 4
055 6 4
060 6 4
070 6 4
075 6 4
090 6 4
100 6 4