Bryant 581B036--072 Installation Instructions Manual page 57

Single-package rooftop heating/cooling standard and low nox units
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PROBLEM
Burners Will Not
Burners Will Not
Misaligned spark electrodes.
Ignite.
I
g
it
No gas at main burners.
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.
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.
Too much outdoor air.
Poor Flame
Incomplete combustion (lack of
Characteristics.
Characteristics.
combustion air) results in:
combustion air) results in:
Aldehyde odors, CO (carbon monoxide),
Aldehyde odors, CO (carbon monoxide),
sooting flame, or floating flame.
ti
Burners Will Not
Unit is locked into Heating mode for a
Turn Off.
one minute minimum.
Table 41—Perfect Humidity™ Adaptive Dehumidification System Subcooling Mode Service Analysis
PROBLEM
Subcooling Mode (Liquid Reheat)
Will Not Energize.
Will Not Energize.
Low System Capacity.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Table 42—Perfect Humidity™ Adaptive Dehumidification System Hot Gas Reheat Mode Service Analysis
PROBLEM
Reheat Mode Will Not Energize.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Excessive Superheat.
Excessive Superheat.
Table 40— Heating Service Analysis
CAUSE
fl
fl
ti
fl
CAUSE
No power to control transformer from
evaporator-fan motor.
No power from control transformer to liquid line
solenoid valve.
Liquid line solenoid valve will not operate.
Liquid line solenoid valve will not open.
Low refrigerant charge or frosted evaporator coil.
Thermostatic expansion valve (TXV).
CAUSE
No power to control transformer from
evaporator-fan motor.
No power from control transformer to hot gas
line solenoid valve
Hot gas line solenoid valve will not operate.
Low refrigerant charge or frosted evaporator coil.
Thermostatic expansion valve (TXV).
Liquid line solenoid valve will not operate.
Hot gas line solenoid valve will not close.
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
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 neces-
sary.
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 nec-
essary.
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 power source and evaporator-fan relay. Ensure all
wire connections are tight.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow
low-pressure switch to reset. Replace switch if it will
not close.
3. Transformer bad; check transformer.
1. Solenoid coil defective; replace.
2. Solenoid valve stuck open; replace.
Valve is stuck closed; replace valve.
1. Check charge amount. Charge per Fig. 55--- 58.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Check power source and evaporator-fan relay. Ensure all
wire connections are tight.
1. Fuse open; check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit off and allow
low-pressure switch to reset. Replace switch if it will
not close.
3. Transformer bad; check transformer.
1. Solenoid coil defective; replace.
2. Solenoid valve stuck closed; replace.
1. Check charge amount. Charge per Fig. 55--- 58.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Valve is stuck, replace valve.
Valve is stuck; replace valve.
57
REMEDY
REMEDY
REMEDY

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