Heating Service Analysis; Durablade Economizer Service Analysis - Carrier 48HJD005-007 Installation, Start-Up And Service Instructions Manual

PROBLEM
Burners will not Misaligned spark electrodes.
ignite.
No gas at main burners.
Water in gas line.
No power to furnace.
No 24 v power supply to control circuit.
Miswired or loose connections.
Burned-out heat anticipator in thermostat.
Broken thermostat wires.
Inadequate heating. Dirty air filter.
Gas input to unit too low.
Unit undersized for application.
Restricted airflow.
Blower speed too low.
Limit switch cycles main burners.
Too much outdoor air.
Poor flame Incomplete combustion (lack of
characteristics. combustion air) results in:
Aldehyde odors, CO (carbon monoxide),
sooting flame, or floating flame.
Burners will not Unit is locked into Heating mode for a
turn off. one minute minimum.
PROBLEM
Damper does not Evaporator fan not on.
open.
No power to economizer motor.
Economizer motor failure.
Economizer OAT or EC set too high.
operation limited to
minimum position.
Check wiring of economizer relay packs.
Check SAT.
Damper does not Incorrect wiring or wiring defects.
close.
Check SAT.
Economizer motor failure.
LEGEND
EC — Enthalpy Control
OAT — Outdoor-Air Thermostat
SAT — Supply-Air Thermostat
SW — Switch
Table 31 — Heating Service Analysis
CAUSE
Table 32 — Durablade Economizer Service Analysis
CAUSE
Check flame ignition and sensor electrode positioning. Adjust as
needed.
Check gas line for air purge as necessary. After purging gas line of
air, allow gas to dissipate for at least 5 minutes before attempting to
relight unit.
Check gas valve.
Drain water and install drip leg to trap water.
Check power supply, fuses, wiring, and circuit breaker.
Check transformer. Transformers with internal overcurrent protection
require a cool-down period before resetting. Check 24-v circuit
breaker; reset if necessary.
Check all wiring and wirenut connections.
Replace thermostat.
Run continuity check. Replace wires, if necessary.
Clean or replace filter as necessary.
Check gas pressure at manifold. Clock gas meter for input. If too low,
increase manifold pressure or replace with correct orifices.
Replace with proper unit or add additional unit.
Clean filter, replace filter, or remove any restrictions.
Use high speed tap, increase fan speed, or install optional blower, as
suitable for individual units, Adjust pulley.
Check rotation of blower, thermostat heat anticipator settings, and
temperature rise of unit. Adjust as needed.
Adjust minimum position.
Check economizer operation.
Check all screws around flue outlets and burner compartment.
Tighten as necessary.
Cracked heat exchanger.
Overfired unit — reduce input, change orifices, or adjust gas line or
manifold pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Wait until mandatory one minute time period has elapsed or reset
power to unit.
Check wiring between G on connection board and evaporator-fan
contactor.
1. Check that SW3 is making proper contact with the damper blade.
2. Check continually across R1 coil. If not connect, replace relay R1.
3. Check diode D18. If diode is not functioning properly, replace D18.
4. Check wiring in economizer relay pack. (See unit label diagram.)
If there is 24 vac power at the motor terminals, but motor is not operat-
ing, replace motor.
1. Set at correct temperature (3 F below indoor space temperature).
2. Check OAT or EC by setting set point above outdoor temperature or
humidity level. If switch does not close, replace OAT or EC.
1. Check continuity across relay R2 coil. If not connected, replace R2
relay.
2. Check continuity across relay R3 coil. If not connected, replace R3
relay.
If supply-air temperature is over 57 F, switch T2 should be closed. If
not, replace SAT.
1. Check switches 2 and 4. If non-operational, replace.
2. Check diode D19. If diode D19 is not functioning properly, replace.
3. Check wiring on economizer and on economizer relay pack. (See
unit label diagram.)
If supply-air thermostat is below 52 F, switch T1 should be closed. If
not, replace SAT.
If there is 24 vac power at motor terminals, but motor is not operating,
replace the motor.
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REMEDY
REMEDY