Troubleshooting Instructions; Troubleshooting Guide - Cambridge Engineering S Series Technical Manual

TROUBLESHOOTING INSTRUCTIONS

TROUBLESHOOTING GUIDE

Problem
I. No Blower Operation
Cambridge Engineering, Inc.
Possible Cause
1. Unit in Reset
a) Outside temperature below LTC setpoint
in Vent Mode
b) Gas Valve not energized during call for
heat cycle
2. Heater Disconnect
a) Disconnect in OFF position
3. Mode Selector Switch on RCS
a) Switch in OFF position
b) Defective Switch
4. Operating Thermostat
a) Thermostat satisfied
b) Open in thermistor circuit
c) Defective thermostat
5. Blower Service Switch
a) Switch in OFF position
b) Defective switch
6. Control Transformer
a) No input voltage
b) Blown control fuse
c) Defective transformer
7. Class 2 Transformer
a) No output voltage
b) Defective transformer
8. Multi-Functional PC Board
a) No input voltage on Terminal G (RCS)
b) Improper wiring
c) Defective board
9. Damper Motor
a) Damper fuse tripped due to damper motor
over-stroking
b) Damper end switch not made
c) Defective damper motor
10. Motor Protection
a) Overload relay tripped
b) Overload relay defective
11. Motor Starter
a) Coil open (Defective)
b) Contacts welded closed (Defective)
12. Motor
a) No input voltage
b) Improper voltage
c) Defective motor
13. Blower
a) Defective or locked bearings
b) Physical damage
14. Belts
a) Belt Slipping
b) Belt broken or missing
48
Corrective Action
a) Turn unit OFF momentarily and turn unit
ON.
b) See Problem III.
a) Turn disconnect ON.
a) Place switch in proper mode.
b) Replace switch.
a) Adjust thermostat, if applicable.
b) Check wiring or replace thermistor.
c) Replace thermostat.
a) Place switch in REMOTE position.
b) Replace switch.
a) Check disconnect and supply fusing.
b) Replace control fuse.
c) Replace transformer.
a) Check supply voltage.
b) Replace transformer.
a) Check voltage in RCS.
b) Check wiring.
c) Replace multi-functional PC board.
a) Adjust damper stroke (page 54).
b) Check end switch/cam interface.
c) Replace damper motor.
a1) Check primary power source.
a2) Reset overload relay and check motor
amps/overload setting.
b) Replace overload relay.
a) Replace starter.
b) Replace starter.
a) Check primary power source.
b) Consult factory.
c) Replace motor.
a) Replace bearings.
b) Replace or repair blower
a) Tighten belts.
b) Replace belts.
S-Series Technical Manual