68
SERVICING
OPEN TO
ATMOSPHERE
INCLINED MANOMETER
HOSE TO INDUCED
DRAFT BLOWER TAP
1/4" TEE
INDUCED DRAFT BLOWER
PRESSURE SWITCH
PRESSURE SWITCH
HOSE
INDUCED
DRAFT
BLOWER
*
*
*
*
*
*
*
M
1
2
3
P
C
ON
O
F
F
COIL COVER
PRESSURE SWITCH
Blower Pressure Switch
Negative Pressure Measurement
S-311 HIGH ALTITUDE APPLICATION (USA)
The furnace as shipped requires no change to run between
0 - 7000 feet. Do not attempt to increase the firing rate by
changing orifices or increasing the manifold pressure below
7000 feet. This can causepoor combustion and equipment
failure. High altitude installations above 7000 feet. feet may
require both a pressure switch and an orifice change. These
changes are necessary to compensate for the natural re-
duction in the density of both the gasfuel and the combus-
tion air at higher altitude.
For installations above 7000 feet, please refer to your dis-
tributor for required kit(s). Contact the distributor for a tabu-
lar listing of appropriate manufacturer’s kits for propane gas
and/or high altitude installations. The indicated kits must be
used to insure safe and proper furnace operation. All conver-
sions must be performed by a qualified installer, or service
agency.
In some areas the gas supplier may artificially derate the
gas in an effort to compensate for the effects of altitude. If
the gas is artificially derated the appropriate orfice size must
be determined based on the BTU/ft
3
content of the derated
gas and the altitude. Refer to the National Fuel Gas Code,
NFPA 54/ANSI Z223.1, and information provided by the gas
supplier to determine the proper orifice size.
S-312 CHECKING FOR DELAYED IGNITION
Delayed ignition is a delay in lighting a combustible mixture
of gas and air which has accumulated in the combustion
chamber.
Furnace design makes this extremely unlikely unless safety
controls have been by-passed or tampered with. Never by-
pass or alter furnace controls.
If delayed ignition should occur, the following should be
checked:
1. Improper gas pressure - adjust to proper pressure (See
S-307 CHECKING GAS PRESSURE
).
2. Improper burner positioning - burners should be in locat-
ing slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed - clean.
4. Main burner orifice(s) deformed, or out of alignment to
burner - replace.
S-313 CHECKING INTEGRATED IGNITION
CONTROL BOARDS
NOTE:
Failure to earth ground the furnace, reversing the
neutral and hot wire connection to the line (polarity), or a
high resistance connection in the neutral line may cause
the control to lockout due to failure to sense flame.
T
O AVOID THE RISK OF ELECTRICAL SHOCK, WIRING TO THE UNIT
MUST BE PROPERLY POLARIZED AND GROUNDED.
D
ISCONNECT POWER
BEFORE PERFORMING SERVICE LISTED BELOW.
WARNING
The ground wire must run from the furnace all the way back
to the electrical panel. Proper grounding can be confirmed
by disconnecting the electrical power and measuring resis-
tance between the neutral (white) connection and the burner
closest to the flame sensor. Resistance should be less than
2 ohms.
The ignition control is a combination electronic and electro-
mechanical device and is not field repairable. Complete unit
must be replaced.
L
INE VOLTAGE NOW PRESENT
WARNING
These tests must be completed within a given time frame
due to the operation of the ignition control.
The ignition control is capable of diagnosing many furnace
failures to help in troubleshooting. The trial for ignition period
is 4 seconds.
Daikin
Brand Two-Stage (DM96VE/DC96VE)
1. Check for 120 volts from Line 1 (Hot) to Line 2 (Neutral)
at the ignition control. No voltage, check the door switch
connections and wire harness for continuity.
2. Check for 24 volts from W to C terminal on the ignition
control. No voltage. Check transformer, room thermo-
stat, and wiring.
If you have 24 volts coming off the transformer but re-
ceive approximately 13 volts on the terminal board be-
tween (C) and (R), check for blown fuse.
3. Check 120 volt outputs on the 5 pin harness.
Pin 1 = HSI Hot
Pin 2 = Inducer High
Pin 3 = Inducer Low
Pin 4 = Inducer N
Pin 5 = HSI N
4. After the ignitor warmup time, begin checking for 24 volts
to the gas valve. Voltage will be present for four seconds
only if proof of flame has been established.
