Carrier Bryant Payne day and night 585A/YAC - Cooling System Startup and Tuning; Cooling System Checks

On units equipped with the RELITE pilot (Figure 14), gas
flows to the pilot gas valve, which is inside of main gas valve
(5D), when the pilot gas cock is open. Since the unit does not
have a standing flame, the unit is now ready for a “call for
heat” from the thermostat.
When the thermostat “calls for heating,” terminal R
“makes” to terminal W through the thermostat.
On units equipped with the glow-coil pilot, the circuit
through the thermostat completes the circuit to the gas
valve (5A).
On units equipped with the RELITE pilot, the circuit
through the thermostat simultaneously energizes the pilot
gas valve (permitting gas flow to the pilot) and the spark
igniter, that sends a high-voltage charge to the pilot
electrode. The pilot electrode sparks for approximately 5 to
10 seconds after a pilot flame is established. The pilot flame
sensing probe senses the pilot flame and permits the circuit
to the gas valve (5D) to be completed.
When the gas valve (5A or 5D) is energized, it opens and sup¬
plies gas to the burners. The pilot flame then ignites the bur¬
ners.
The 821 heating blower relay (2G) was energized when the
circuit through the thermostat was completed. After a short
delay, the blower relay (2G) contacts close and the circuit to
the blower motor (3D) is completed. This circuit energizes
the motor to start the blower.
When the thermostat is satisfied, the circuit between R and
W within the thermostat will break. On units equipped with
the glow-coil pilot, the circuit to gas valve (5A) is
deenergized and gas flow to the burners is stopped. On units
equipped with the RELITE pilot, the broken thermostat cir¬
cuit deenergizes the pilot gas valve and gas flow to both the
pilot and the burners is stopped. Heating blower relay (2G)
is also deenergized. There will be a delay before the heating
relay (2G) contacts open. When these contacts do open, the
blower motor (3D) is deenergized.
Both types (glow-coil or RELITE pilot) of units are now in a
“standby” condition, waiting for the next “call for heat”
from the thermostat.
G. Limit Switch Operation
The furnace limit switch (7K) functions to shut off“ gas and
main burner operation if the furnace becomes overheated.
See Figures 13 and 14. The limit switch is a temperature-
actuated switch.
Ibrminal No. 1 of the limit switch is a common terminal and
is internally connected to the switch terminal No. 3 as long
as the temperature at the limit switch is below 175° 5°F.
When the temperature near the limit switch rises to
175° 5°F, switch terminal No. 3 is opened, and terminal No.
2 is now internally connected to switch terminal No. 1. This
breaks the circuit to the gas valve (5A or 5D) and shuts off
all gas supply to the burners. The control circuit is still
closed to blower relay (2G) and the blower motor (3D) will
continue to run as long as the temperature is above the limit
setting. When the temperature at the limit switch drops to
130° 5°F, switch terminal No. 3 will again be internally
connected to switch terminal No. 1. The gas valve will again
be energized and supply gas to the burners.
VML COOLING STARTUP AND ADJUSTMENTS
CAUTION: Complete the steps in Section VII before start¬
ing unit.
CAUTION: Do not jumper any safety devices when operat¬
ing unit.
A. Checking Components
Perform the following steps before starting the unit.
1. Check for correct position of condenser fan blade in unit
top panel. See Figure 3.
2. Leak-test all refrigerant circuit connections to make
certain that none has been damaged in shipment.
3. Check entire system for leaks at all connections, includ¬
ing evaporator coil located in blower compartment. (Use
electronic leak detector, halide torch, or liquid-soap
solution.)
NOTE: The cooling section is fully charged with re¬
frigerant, tested, and factory-sealed. There should be no
need to check refrigerant charge if no leaks were
found.
In rare instances, when the refrigerant charge may have
been lost because of a leak caused by shipping or if a re¬
frigerant leak has been found, proceed as follows:
a. Locate and repair leak.
WARNING: Never attempt to repair any soldered connec¬
tion while system is under pressure. Severe bodily injury
may result.
b. Leak-test unit.
c. Evacuate system.
d. Charge unit with proper type and amount of re¬
frigerant.
CAUTION: The type and amoimt of refrigerant are listed
on unit rating plate. It is recommended that a volumetric
charging cylinder or an accurate scale be used when charg¬
ing is necessary. Charge unit with exact amount of re¬
frigerant as shown on unit rating plate,
4. Check to be sure all tools and loose parts have been re¬
moved.
5. Check to be sure all panels and covers are in place. Fol¬
lowing this initial inspection, unit may be started.
NOTE: Check three-phase evaporator blower motor for cor¬
rect rotation. Direction of rotation is indicated by arrow on
blower housing. If blower rotates in opposite direction, re¬
verse any two blower motor leads or any two line-voltage
leads. After leads are reversed, recheck blower rotation.
B. Evaporator Airflow
All 585A/YAC, 585A/YACR, and 586A/YACX units are
equipped with direct-drive blower motors. Motor speeds have
been factory-set for both heating and cooling to obtain
optimum performance. See Tables VI and VII to determine
airflow. On most units the motor speeds cannot be adjusted;
however, some units do have unused speed taps that are
available. See the unit wiring label.
NOTE: Recommended evaporator airflow is 350 to 450 CFM
per 12,000 Btuh of cooling.
NOTE: Optional field-installed high-static blower packages
are available for the 585A/YAC and 585A/YACR, sizes
036080 through 060150. Refer to Table VII to determine the
airflow for these optional blowers. (Same as blowers used in
equivalent sizes of the 586A/YACX.)
C. Checking Unit Operation
Perform the following steps to make certain the unit is
operating properly:
1. Place thermostat system switch in COOL position; place
FAN switch in AUTO position; set thermostat setting
below room temperature. Observe that compressor, con-
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