8
Y99AB-4 BASO Test Kit Application Note
Troubleshooting
The following table indicates symptoms and corrective actions.
Table 3: Troubleshooting Symptoms and Corrective Actions
Symptom
Possible Cause
Corrective Action
Excessive draft
Baffle secondary air or shield pilot burner.
Recirculation of flue products
Check venting and main orifice sizing and
correct where necessary.
Excessive temperature
Check main burner input and correct if
necessary.
Improper pilot flame size or
characteristic
Check gas pressure, clean pilot burner,
and adjust flame.
Defective thermocouple
Perform the
Open Circuit Millivolt
Readings
procedure.
Pilot burner outage, varying
performance, or poor mV output.
Weak holding BASO power unit
Perform the
Dropout Testing
procedure.
Defective thermostat
Perform the
Continuity Testing
procedure.
Pilot burner burning, manual valve
(if included) turned to the “On”
position, thermostat calling for
heat. Main burner does not come
on.
Defective operator
Check for operator input voltage. If present,
replace the valve. If not, check voltage
source.
Shorted thermostat circuit
Perform the
Continuity Testing
procedure.
Thermostat not calling for heat, or
turned down, manual valve (if
included) in the “On” position. Main
burner does not shut off.
Foreign particles lodged between
the valve seat
Replace the valve.
Thermocouple out of position
Reposition thermocouple properly.
Thermocouple lead dirty or loose
Clean and tighten thermocouple lead
connection.
Defective thermocouple
Perform the
Open Circuit Millivolt Readings
procedure.
Defective BASO power unit
Perform the
Dropout Testing
procedure.
Defective orifice
Clean or replace orifice.
No burner flame or flame does not
stay on.
Unusually strong drafts
Baffle secondary air or shield burner.
Controls Group
507 E. Michigan Street
P.O. Box 423
Printed in U.S.A.
Milwaukee, WI 53201
www.johnsoncontrols.com
