Carrier 58DX - Manual (Page 6)

after MGV solenoid coil is energized, heating relay coil
HFR is deenergized, closing the 115-VAC contacts of
heating relay HFR and steirting blower motor MTR on
heating speed. The H terminal is energized with 24
VAC when the blower motor is operating on heating
speed. Electronic air cleaner terminals (EAC) are ener­
gized with 115 VAC when the blower is operating on
either heating or cooHng speed.
8. When the thermostat is satisfied, the R and W circuit
is broken, deenergizing gas valve GV, and the solid-
state time-delay circuits for the inducer motor relay
IDR and blower motor relay HFR. The gas flow to the
pilot and main burners immediately stops. After
approximately 15 seconds, induced draft motor relay
IDR is deenergized and induced draft motor IDM
stops. Approximately 80 to 240 seconds (depending on
the blower off-time adjustment) after main burners are
extinguished, heating relay HFR is energized and
blower motor MTR stops.
NOTE: After a brief interruption of either the electric or
gas supply, the furnace will not resume operation until the
contacts of pilot-flame sensing switch PS move from the
normally open position to the normally closed position.
Cooling Cycle
1. The wall thermostat “calls for coohng.”
2. The R, G, and Y circuits are energized. Simultaneously,
the R and Y circuit starts the outdoor condensing unit,
and the R and G circuit energizes cooling relay coil
CFR. Normally open cooling contacts CFR close, ener­
gizing the cooling speed of motor MTR and opening the
normally closed contacts of cooling relay CFR. The
EAC terminals are energized with 115 VAC when the
blower is operating on either heating or cooling speed.
IX. FILTER ARRANGEMENT
The two factory-suppHed filters are shipped in the blower
compartment. After the retum-air duct has been connected
to the furnace, install the filters (with cross-hatch binding
facing blower) in a V-formation inside the retum-edr plenum.
See Fig. 9.
A WARNING
Never operate the unit without a filter or with the filter
access door removed. A failure to adhere to this warn­
ing can cause a fire, physical injury, or death.
X. STARTUP AND ADJUSTMENT
In addition to the following information, refer to “Proce­
dures for Downflow Condensing Furnaces.”
NOTE: The furnace blower access panel must be in place to
complete the 115-volt circuit to the furnace.
A CAUTION
This furnace is equipped with a fusible link in the
burner enclosure. This link will melt if an over-heating
condition caused by an inadequate combustion-air sup­
ply or improper venting practices develops. DO NOT
jumper this fuse. Correct the condition and replace the
fuse with an identical part.
The gas service pressure must not exceed 0.5 psig (14 in. wc)
for natural gas.
NOTE: The gas valve regulator has been nominally-set at
3.5 in. wc for natural gas. Refer to “Procedures for Down­
flow Condensing Furnaces” for readjusting and checking
input.
A CAUTION
The unit must not be installed, operated, and then
turned off and left turned off, in an unoccupied struc­
ture during cold weather when the temperature drops
to 32 °F and below. Freezing condensate left in the fur­
nace will damage the equipment.
A. When winterizing the furnace, it is necessary to
proceed as foilows:
1. Mix a solution of equal amounts of ethylene glycol
(Prestone II antifreeze coolant or equivalent) and
water.
2. Turn off electrical supply to furnace.
3. Remove control emd blower access panels.
4. Disconnect drain tube from bottom of inducer outlet
elbow.
5. Insert funnel in drain tube and pour antifreeze/water
solution into furnace until it is visible at point where
condensate enters open drain.
6. Reconnect dredn tube to outlet elbow.
7. Replace control access panel.
B. Adjustment of Blower Speed
A CAUTION
Disconnect the electrical power before changing the
speed tap. A failure to adhere to this warning can cause
personal injury.
To change motor speed taps, remove the motor tap lead (See
Table 5.) and relocate it on the desired terminal on the plug-
Table 5—Speed Selector '
Speed Tap No.*
Common C
Hi 1
Med-Hi 2
Med-Low 3
Low 4
*White wire from control box to common; black wire from control box to
cooling speed selection; red wire from control box to heating speed
selection.