SA-Series Technical Manual
33
Cambridge Air Solutions
Problem
Possible Cause
Corrective Action
VIII. MODULATING
VALVE DOES NOT
MODULATE;
CONTINUOUS
HIGH FIRE
(Continued)
3. Space Temperature Selector
(CE-Smart
TM
)
a) Open in sensor circuit
b) Induced voltage in field wiring
c) Space sensor located improperly
a) Replace the sensor if the resistance
measured is less than 3,500 Ω for the
TS244A and 1,950 Ω for the TD244A
b) Utilize shielded, twisted pair wiring
c) Sensor in cold draft - relocate
4. Modulating Valve
a) Foreign material holding valve open
a) Replace valve
IX. MODULATING VALVE
DOES NOT
MODULATE;
CONTINUOUS
LOW FIRE
1. Class II Transformer
a) No voltage output to amplifier
a1) Check for short in modulating valve coil
a2) Replace transformer
2. Modulating Valve
a) Valve coil is open or shorted
b) Plunger jammed
c) Ruptured main or balancing diaphragm
a) Replace valve if coil resistance is less than
40 Ω or greater than 85 Ω
b) Replace valve
c) Replace valve
3. Amplifier
a) No output voltage to valve
a) With the wire removed from terminal 3
of amplifier, replace amplifier if the valve
voltage does not exceed 18 Volts DC
4. Space Temperature Selector
(CE-Smart)
a) Short in sensor circuit
a) Replace the sensor if the resistance
measured is less than 3,500 Ω for the
TS244A and 1,950 Ω for the TD244A
5. Multi-Functional PC Board
a) Terminal X has power
b) Defective board
a) Determine power source
b) Replace board
TROUBLESHOOTING INSTRUCTIONS
TROUBLESHOOTING GUIDE
