Component Test - Carrier 58DXT Service And Maintenance Instructions

If status code recall is needed, do not remove power or blower door. Briefly remove and
then reconnect one main limit wire to display stored status code.
LED CODE
CONTINUOUS OFF - Check for 115VAC at L1 and L2, and 24VAC at SEC1 and SEC2.
CONTINUOUS ON - Control has 24VAC power.
RAPID FLASHING - Line voltage (115VAC) polarity reversed. If twinned, refer to
twining kit instructions.
EACH OF THE FOLLOWING STATUS CODES IS A TWO-DIGIT NUMBER WITH THE FIRST DIGIT DE-
TERMINED BY THE NUMBER OF SHORT FLASHES AND THE SECOND DIGIT BY THE NUMBER OF
LONG FLASHES.
NO PREVIOUS CODE - Stored status codes are erased when power
11
(115VAC or 24VAC) to control is interrupted or 48 hours after each fault is cleared.
BLOWER ON AFTER POWER UP (115VAC or 24 VAC) - Blower runs for 90 seconds,
12
if unit is powered up during a call for heat (R-W closed).
LIMIT OR FLAME ROLL-OUT SWITCH LOCKOUT - Control will auto reset after three
13
hours. Reset switch or replace fuse link. Refer to #33
IGNITION LOCKOUT - Control will auto-reset after three hours. Refer to #34
14
GAS HEATING LOCKOUT - Control will NOT auto-reset.
21
Check for: - Mis-wired gas valve
22 ABNORMAL FLAME-PROVING SIGNAL - Flame is proved while gas valve is
de-energized. Inducer will run until fault is cleared.
Check for: - Leaky gas valve
PRESSURE SWITCH DID NOT OPEN
23
- Obstructed pressure tubing
SECONDARY VOLTAGE FUSE IS OPEN
24
Check for: - Short-circuit in secondary voltage (24VAC) wiring
HIGH-HEAT PRESSURE SWITCH OR RELAY DID NOT CLOSE OR REOPENED
31
Check for: - Control relay may be defective
LOW HEAT PRESSURE, DRAFT SAFEGUARD, AUX-LIMIT (when used*) SWITCH DID NOT
32
CLOSE OR REOPENED (DOWNFLOW ONLY*) If open longer than five minutes,
inducer shuts off for 15 minutes before retry. Check for:
- Proper vent sizing
- Defective Blower motor or capacitor
*
- Defective pressure switch
- Inadequate combustion air supply
- Disconnected or obstructed pressure tubing
period, blower will come on for 90 second recycle delay.
LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN - If open longer than three
33
minutes, code changes to #13. Flame roll-out switch requires manual reset.
Check for: - Dirty filter or restricted duct system.
- Defective blower motor or capacitor.
- Inadequate combustion air supply (Flame Roll-out Switch or fuse link open).
- Open Flame Roll-out switch, or fuse link. Manual reset or replace.
IGNITION PROVING FAILURE - Control will try three more times before lockout #14
34
occurs. If flame signal is lost after trial for ignition period, blower will come on for
90 second recycle delay. Check for: - Gas valve defective or gas valve turned off.
- Oxide buildup on flame sensor (clean with fine steel wool).
- Proper flame sense microamps (.5 microamps D.C. min., 4.0 - 6.0 nominal in
HIGH HEAT). - Green wire MUST be connected to furnace sheet metal.
- Flame sensor must be ungrounded.
- Defective Hot Surface Ignitor
- Inadequate flame carryover or rough ignition.
LOW-HEAT PRESSURE, DRAFT SAFEGUARD, OR AUXILIARY LIMIT (when used*) SWITCH
43
OPEN WHILE HIGH HEAT PRESSURE SWITCH IS CLOSED
- Disconnected or obstructed pressure tubing
- Pressure switch stuck open
REPLACE CONTROL
45

COMPONENT TEST

C
OM
W2 W/W1 Y/Y2
24 V
To initiate the component test sequence, shut "OFF" the room thermostat or
disconnect the "R" thermostat lead. Briefly short TWIN/TEST terminal to
"Com 24 V" Terminal. Status LED will turn off, control will turn "ON" the inducer motor-
low speed, inducer motor-high speed, hot surface ignitor, blower motor-low gas
heat speed, blower motor-high gas heat speed and blower motor-high cool
speed for 7-15 seconds each. Gas valve and humidifier will not be turned on.
→ Fig. 12—Service Label
SERVICE
STATUS
- Defective control (valve relay)
- Stuck-open gas valve
Check for:
- Pressure switch stuck closed.
- Refer to #32
- Low inducer voltage (115VAC)
- Defective inducer motor
- Restricted vent
- Excessive wind
If it opens after trial for ignition
- Loose blower wheel.
- Defective switch or connections.
- Manual valve shut-off.
- Control ground continuity.
- Low inlet gas pressure.
- Refer to #32 and #33
TWIN
TEST
R G LED
HUM
9
Check for:
320893-101 REV. D (LIT)
A99149