S-Series Technical Manual
83
Cambridge Air Solutions
TROUBLESHOOTING INSTRUCTIONS
TROUBLESHOOTING GUIDE
Problem
Possible Cause
Corrective Action
I. No Blower Operation
1. Unit in Reset
a) Outside temperature below LTC setpoint
in Vent Mode
b) Gas Valve not energized during call for
heat cycle
a) Turn unit OFF momentarily and turn unit
ON.
b) See Problem III.
2. Heater Disconnect
a) Disconnect in OFF position
a) Turn disconnect ON.
3. Mode Selector Switch on RCS
a) Switch in OFF position
b) Defective Switch
a) Place switch in proper mode.
b) Replace switch.
4. Operating Thermostat
a) Thermostat satisfied
b) Open in thermistor circuit
c) Defective thermostat
a) Adjust thermostat, if applicable.
b) Check wiring or replace thermistor.
c) Replace thermostat.
5. Blower Service Switch
a) Switch in OFF position
b) Defective switch
a) Place switch in REMOTE position.
b) Replace switch.
6. Control Transformer
a) No input voltage
b) Blown control fuse
c) Defective transformer
a) Check disconnect and supply fusing.
b) Replace control fuse.
c) Replace transformer.
7. Class 2 Transformer
a) No output voltage
b) Defective transformer
a) Check supply voltage.
b) Replace transformer.
8. Multi-Functional PC Board
a) No input voltage on Terminal G (RCS)
b) Improper wiring
c) Defective board
a) Check voltage in RCS.
b) Check wiring.
c) Replace multi-functional PC board.
9. Damper Motor
a) Damper fuse tripped due to damper motor
over-stroking
b) Damper end switch not made
c) Defective damper motor
a) Adjust damper stroke (page 54).
b) Check end switch/cam interface.
c) Replace damper motor.
10. Motor Protection
a) Overload relay tripped
b) Overload relay defective
a1) Check primary power source.
a2) Reset overload relay and check motor
amps/overload setting.
b) Replace overload relay.
11. Motor Starter
a) Coil open (Defective)
b) Contacts welded closed (Defective)
a) Replace starter.
b) Replace starter.
12. Motor
a) No input voltage
b) Improper voltage
c) Defective motor
a) Check primary power source.
b) Consult factory.
c) Replace motor.
13. Blower
a) Defective or locked bearings
b) Physical damage
a) Replace bearings.
b) Replace or repair blower
14. Belts
a) Belt Slipping
b) Belt broken or missing
a) Tighten belts.
b) Replace belts.
