Filter
Top Products
61
Table 42— Heating Service Analysis
PROBLEM CAUSE REMEDY
Burners Will Not
Ignite.
Misaligned spark electrodes. Check flame ignition and sensorelectrode positioning. Adjust as needed.
No gas at main burners. Check gas line for air purge as necessary. After purginggas line of air, allow gas
to dissipate for at least 5 minutes before attempting to relight unit.
Check gas valve.
Water in gas line. Drain water an d in stall drip leg to trap water.
No power to furnace. Check power supply, fuses, wiring, and circuit breaker.
No 24 v power supply to control circuit. Check transformer. Transformerswith internal overcurrent protection requirea
cool-down period before resetting. Check 24-v circuit breaker; reset if neces-
sary.
Miswired or loose connections. Check all wiring and wirenut connections.
Burned-out heat anticipator in thermostat. Replace thermostat.
Broken thermostat wires. Run continuity check. Replace wires, if necessary.
Inadequate Heating. Dirty air filter. Clean or replace filter as n ecessary.
Gas input to unit too low. Check gas pressure at manifold.Clock gas m eter for input. If too low, in crease
manifold pressure orreplace with correct orifices.
Unit undersized for application. Replace with proper unit or add additional unit.
Restricted airflow. Clean filter, replace filter, or remove any restrictions.
Blower speed too low. Use high speed tap, increase fan speed, or install optional blower, a s suitable
forindividual units,Adjust pulley.
Limitswitchcyclesmainburners. Check rotation of blower, thermostat heat anticipator settings,and temperature
rise of unit. Adjust as needed.
Too much outdoor air. Adjust minimum position.
Check economizer operation.
Poor Flame
Characteristics.
Incomplete combustion (lack of
combustion air) results in:
Aldehyde odors, CO (carbon monoxide),
sooting flame, or floating flame.
Check all screws around flue outlets and burner compartment. Tight en as nec-
essary.
Crackedheat exchanger.
Overfired unit — reduce input, change orifices, or adjust gas line or manifold
pressure.
Check ven t for restriction. Clean as necessary.
Check orifice to burner alignmen t.
Burners Will Not
Turn Off.
Unit islocked into Heating mode for a
one minute minimum.
Wait until mandatory one-minute time period has elapsed or reset power to
unit.
Table 43—Humidi-MiZer Adaptive Dehumidification System Subcooling Mode Service Analysis
PROBLEM CAUSE REMEDY
Subcooling Mode (Liquid Reheat)
Will Not Energize.
No power to control transformer from
evaporator-fan m otor.
Check power source and evaporator-fan relay. Ensure all
wire connections aretight.
No power from control transformer to liquid line
solenoid valve.
1. Fuse open;check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit o ff and allow
low-pressure switch to reset. Replace s witch if it will
not close.
3. Transformer bad; check transformer.
Liquid line solenoid valve will not operate. 1. Solenoid coil defective; replace.
2. Solenoid valve stuck open; replace.
Liquid line solenoid valve will not open. Valve is stuck closed; replace valve.
Low System Capacity . Low refrigerant charge or frosted evaporator coil. 1. Check charge amount. Charge per Fig. 64-67.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Thermostatic expansion valve (TXV). 1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Table 44—Humidi-MiZer Adaptive Dehumidification System Hot Gas Reheat Mode Service Analysis
PROBLEM CAUSE REMEDY
Reheat Mode Will Not Energize. No power to control transformer from
evaporator-fan m otor.
Check power source and evaporator-fan relay. Ensure all
wire connections aretight.
No power from control transformer to hot gas
line solenoid valve
1. Fuse open;check fuse. Ensure continuity of wiring.
2. Low-pressure switch open. Cycle unit o ff and allow
low-pressure switch to reset. Replace s witch if it will
not close.
3. Transformer bad; check transformer.
Hot gas line solenoid valve will not operate. 1. Solen oid coil defective; replace.
2. Solenoid valve stuck closed; replace.
Low refrigerant charge or frosted evaporator coil. 1. Check charge amount.Charge perFig.64---67.
2. Evaporator coil frosted; check and replace low-pres-
sure switch if necessary.
Loss of Compressor Superheat
Conditions with Subcooling/Reheat
Dehumidification Coil Energized.
Thermostatic expansion valve (TXV). 1. Check TXV bulb mounting, and secure tightly to suc-
tion line.
2. Replace TXV if stuck open or closed.
Excessive Superheat. Liquid line solenoid valve will not operate. Valve is stuck, replace valve.
Hot gas line solenoid valve will not close. Valve is stuck; replace valve.
48HE,HJ