23
SERVICE GUIDE FOR FURNACES WITH
PGB POWER BURNER WITH DIRECT
IGNITION
!
CAUTION:
Verify proper operation after servicing.
!
IMPORTANT:
1. Always disconnect power before ser-
vicing.
2. Only persons trained and experienced
in direct ignition systems should ser-
vice this equipment.
3. If a condition exists that causes the
ignition control to go into safety
lockout, meter readings must be
taken quickly after restart - within trial
for ignition period.
4. Always de-energize the system for at
least 45 seconds before recy-
cling for further tests.
5. The ignition control cannot be repaired.
If the troubleshooting procedure
indicates a malfunction in the con-
trol, it must be replaced.
!
CAUTION:
Label all wires prior to disconnection
when servicing controls. Wiring Errors
can cause improper and dangerous op-
eration.
A. Burner motor does not run - thermostat
calls for heat.
1. Defective thermostat circuit - bridge
TT connections on burner junction
box, if burner motor runs, check:
a. Thermostat connections
b. Thermostat
2. No voltage to burner - plug test lamp
into burner plug receptacle, if it does
not light, check for:
a. Blown fuse, electric supply off
b. Door switch not making contact
c. Limit switch in open mode
d. Check for clean air filter and proper
airflow
e. Loose wire connections
f. Check for tripped manual reset aux-
iliary limit.
3. 120 volts is available to burner - Test
lamp does not light. Remove junction
box cover on burner, check for:
a. Loose wires
b. Defective transformer
c. Defective motor
B. Burner motor does not run, no main flame.
1. Defective centrifugal switch
a. Check the operation of centrifugal
switch by removing end bell of the
burner motor.
2. Check for gas supply - gas line valve
on, control lever on.
3. Check for burner safety lockout. (Re-
start burner)
4. Check for 24 volts to ignition control
a. No voltage at purge timer - check
the centrifugal switch in the com-
bustion motor.
b. No voltage to ignition control - check
purge timer (allow one minute for
purge timer to activate).
c. Check for 120 volts to ignition con-
trol. (-Voltmeter at L1 and L2).
C. Ignition control is powered (120v and 24v).
Ignitor does not heat up.
1. Remove AMP plug from burner tube
receptacle and check for 120 volts at
the plug during ignition sequence
2. Replace ignition control if 120 volts is
not supplied to AMP plug within 3 min-
utes of ignition cycle start.
D. 120 volts is available at AMP plug. Ignitor
does not heat up.
1. Disconnect burner plug from furnace
receptacle.
2. Disconnect AMP plug from burner tube
receptacle and check ignitor circuit
through receptacle with an ohmmeter.
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