M-Series Technical Manual
97
Cambridge Air Solutions
Problem
Possible Cause
Corrective Action
I. No Blower Operation
1. Make-up air heater in Reset
a) Outside temperature below LTC
setpointin Vent Mode
b) Gas Valve not energized during call for
heat cycle
c) Pressure drop across burner too high
d) Sustained excessive winds present
e) High Air Flow Switch defective
a) Turn heater “OFF” momentarily and turn
heater “ON.”
b) See Problem III.
c) Adjust Profile Plate Damper.
d) Wait until winds abate and reset.
e) Replace High Air Flow Switch.
2. Heater Disconnect
a) Disconnect in OFF position
a) Turn disconnect ON.
3. Mode Selector Switch on RCS
a) Switch in OFF position
a) Place switch in proper mode.
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 End Switch not made
b) Damper motor not operating
c) Defective damper motor
a) Check end switch/cam interface.
b) Check end switch/cam interface.
b1) Check damper fuse.
b2) Check diodes on switch assy.
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 Damage
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.
TROUBLESHOOTING GUIDE
