Schwank P40U Fenwal - Manual (Page 29)

29
P40U-F / P40U-IF I&O Manual
IM101220
RD: MAY 2014
RL: 5A
SERVICE CHECKS
Flame current passes through the flame from the
sensor to ground. The minimum flame current
necessary to keep the system from lockout is 0.7
microamps. To measure flame current, connect
an analog DC microammeter to the FC- FC+ ter-
minals per figure at right.
Meter should read 0.7 µA or higher. If the meter
reads below “0” on scale, meter leads are re-
versed. Disconnect power and reconnect meter
leads for proper polarity.
FC- FC+
Use Microamp
scale
Multipurpose Meter
TROUBLESHOOTING - FENWAL DSI
(also see Heater Troubleshooting Page 33)
SYMPTOM RECOMMENDED ACTION(S)
1. Dead
A. Miswired - check electrical supply (120Vac ± 5%)
B. Transformer bad (24Vac ± 10%)
C. Fuse/Circuit breaker bad
D. Bad control (check LED for steady on)
2. Thermostat on
- no blower output
A. Miswired
B. Bad thermostat no voltage @ terminal W
C. Bad control (check LED for steady on)
3. Pressure switch input okay,
but no Trial-for-Ignition
after purge delay
A. Miswired (check PSW terminal voltage: 24Vac ± 10%)
B. Flame sense problem (existing flame: check LED - 2
flashes)
C. Bad control (check line voltage between L1 & IND)
4. Valve on, no spark
A. Shorted electrode
B. Open HV cable
C. Bad control
5. Spark on, no valve
A. Valve coil open
B. Open valve wire
C. Bad control (check 24Vac voltage between V1 & V2)
6. Flame ok during TFI, no
flame sense (after TFI)
A. Bad electrode
B. Bad HV igniter wire
C. Poor ground at burner
D. Poor flame (check flame current)