Carrier 58MCA Heating System User Manual


 
11 NO PREVIOUS FAULT - Faults
are erased after 48 hrs or
whenever power (115v or 24v) is
interrupted. Run system through
a heating or cooling cycle to 
check system.
12 BLOWER ON AFTER POWER
UP (115V OR 24V) - Normal 
operation. Blower will run for 90
sec when furnace power is
interrupted during a call for heat,
R-W closed.
13 LIMIT OR FLAME ROLLOUT
SWITCH LOCKOUT -
Limit switch was open longer
than 3 minutes. Auto-reset will
occur after 3 hrs. Flame rollout
switch requires manual reset.
See No. 33
14 IGNITION LOCKOUT - System
failed to ignite gas and prove
flame in 4 attempts. Control will
auto-reset in 3 hrs.
See No. 34
21 GAS HEATING LOCKOUT - 
Turn off power and wait 5
minutes to retry.
Check for:
Unplug ignitor harness from control
center and inititate another 
component test sequence. Check
for 115v between pins 1 and 2 on
the control center. Was 115v present
for the 17-sec period?
Replace control center.
Check for continuity in the harness
and ignitor. Replace defective
component.
Reconnect the R thermostat lead
and set thermostat to call for heat.
Connect voltmeter across gas valve
connections. Does gas valve
receive 24v?
Check connections. If OK, replace
control center.
Does gas valve open and allow gas
to flow?
Check that all gas valves are turned
on. Replace valve.
Do main burners ignite?
Do main burners stay on?
Allow blower to come on and repeat
test to check for intermittent
operation.
Repeat call for heat and check flame
sensor current during trial for ignition
period. Is the DC microamps
below 0.5?
Check connections and retry. If 
current is near typical value and
control will not stay on, replace
control center.
Clean flame sensor with fine
sandpaper and recheck current. 
Current is nominally 4.0 to 6.0 microamps.
Is current near typical value?
Replace electrode.
Will main burner ignite and stay on?
Replace control center.
Fixed.
Stuck closed gas valve relay
on control.
Miswire or short to gas valve
wire.
22 ABNORMAL FLAME PROVING
SIGNAL - Flame was sensed
while gas valve was
de-energized. Inducer will run
until fault is cleared.
Check for:
Stuck open gas valve solenoid
or leak.
Defective control center.
23 PRESSURE SWITCH WILL
NOT OPEN - Check for:
Disconnected or obstructed
pressure tubing.
Defective pressure switch.
24 LOW-VOLTAGE FUSE IS
OPEN - Check for:
Short in low-voltage wiring
including thermostat leads
shorting to ductwork or
furnace cabinet. Disconnect
thermostat leads to isolate
short circuit.
31 PRESSURE SWITCH WILL
NOT CLOSE OR REOPEN - If
open longer than 5 minutes,
inducer shuts off for 15 minutes
before retry. 
Check for:
Proper vent sizing or pitch or
sag.
Vent restrictions or high winds.
Defective inducer motor.
Low line voltage (115v).
Motor start capacitor.
Low inlet gas pressure.
Defective pressure switch or
connections. If it opens after
trial for ignition period, blower
will come on for 90 sec
recycle delay.
Inadequate combustion air.
33 LIMIT OR FLAME ROLLOUT 
SWITCH IS OPEN - If 
limit switch is open longer than 3
minutes, code changes to No. 13.
Check for:
Blower motor failure.
Motor start capacitor.
Open flame rollout switch, 
manual reset.
Dirty filter.
Defective limit switch or 
connections.
Loose blower wheel.
34 IGNITION PROVING FAILURE -
If flame is not sensed during the
trial for ignition period, the control
will repeat the ignition sequence
3 more times before going into
lockout, No. 14.
If flame signal is lost after trial for
ignition period, blower will come
on for 90-sec recycle delay.
Check for the following items first
before proceding to the next step.
Gas valve turned off.
Manual shut-off valve.
Green wire must be connected
to furnace sheet metal.
To determine whether the
problem is in the gas valve,
ignitor, or flame sensor, the
system can be operated in the
component test mode to check
the ignitor. First, remove the
R thermostat connection from the
control center and initiate the
component test sequence. Does
the ignitor glow orange/white hot
by the end of the 17-sec warm-up
period?
Check for:
Inadequate flame carryover on
rough ignition.
Low inlet gas pressure.
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
Inadequate combustion air 
supply (flame rollout switch
only).
NO
A96219
15