S-Series Technical Manual
85
Cambridge Air Solutions
Problem
Possible Cause
Corrective Action
III. BLOWER RUNS;
NO HEAT; FLAME
SAFETY RELAY
LOCKS OUT
(Continued)
7. Regulator
a) Clogged vent orifice
b) No supply pressure
c) Improper manifold pressure
d) Defective regulator
a) Clean or replace orifice.
b) Check all gas cocks and piping.
c) Adjust regulator.
d) Replace regulator.
8. Burner
a) Defective burner
a) Replace burner.
IV. BLOWER RUNS;
BURNER FIRES;
FLAME SAFETY
RELAY LOCKS OUT
1. Low Flame Current
a) Dirt build-up on ceramic body
b) Minimum fire set too low
c) Defective burner
a) Clean dirt deposit from ceramic body and
install protective boot.
b) Adjust minimum fire on modulating valve.
c) Replace burner.
2. Multi-Functional PC Board
a) Low fire start set too low
a) Adjust modulating valve voltage between
10 and 13 Volts DC.
3. No Flame Current
a) Ground connection open
b) Wire termination oxidized
a1) Reference transformer to ground.
a2) Secure ground between control enclosure
and burner.
a3) Tighten loose ground screws.
b) Clean terminal and reinsert.
4. Fluctuating Flame Current
a) Unit overfiring
b) Minimum fire set too low
c) Intermittent ground connection
d) Loose terminal on Flame Rod
e) Defective burner
a) Check manifold pressure.
b) Adjust minimum fire on modulating valve.
c) Tighten all ground points.
d) Remove jam nuts from Flame Rod.
Reassemble with terminal located
between jam nuts on Flame Rod.
e) Replace burner.
5. Flame Safeguard Relay
a) Defective FSR
a) Replace FSR.
6. High Limit
a) High limit contact intermittent
a) Replace high limit.
V. BLOWER RUNS;
UNIT HEATS;
SHORT CYCLES
WITHOUT
RESETTING
1. Air Flow Switch
a) Blower running backwards
b) Belts slipping
c) Blocked intake or discharge
d) Air delivery below unit specs
e) Clogged airflow tubing or pick-up ports
f) Defective switch
a) Reverse motor direction.
b) Tighten and/or replace belts.
c) Find and remove obstruction.
d) Increase fan RPM for air delivery
requirements.
e) Clean or replace airflow tubing or pick-up
ports.
f) Replace switch.
2. Flame Safeguard Relay
a) Defective FSR
a) Replace FSR.
3. Operating Thermostat
a) Differential temperature setting too tight
b) Open or short in thermistor circuit
a) Increase differential temperature setting.
b) Check wiring or replace thermistor.
4. Damper Motor End Switch
a) End switch making intermittent contact
a) Replace end switch assembly.
TROUBLESHOOTING INSTRUCTIONS
TROUBLESHOOTING GUIDE
