Carrier 48EL - Manual (Page 10)

Lubrication
FAN MOTOR BEARINGS are factory lubricated
and do not require service for 3 to 5 years,
depending upon type of service. When required,
clean and relubricate per motor manufacturer’s
instructions.
COMPRESSOR contains a factory oil charge. If oil
is lost thru leakage, refer to Carrier Standard
Service Techniques Manual SM-1, Chapter 1 for oil
recharging procedure.
TROUBLESHOOTING - HEATING SYSTEM
Burner Does Not Operate
Power failure — Power switch off; blown line
fuse; defective wiring. .
No power to controls — thermostat set too low,
dirty or defective; defective transformer, faulty
limit switch.
Burner does not ignite — no gas to unit; faulty
valve or pilot switch; faulty spark ignitor; dirty
pilot.
Burner Operates, But Heating is Inadequate
Unit undersized — unit size selected incorrectly
Fuel input too low ~ wrong orifice size,
regulator set too low
Thermostat opens too soon ~ wrong antici­
pator setting, thermostat out of calibration,
wrong thermostat location; thermostat set
wrong.
Limit switch cycles burner
faulty fan switch or motor;
wrong; duct system restricted
Poor Combustion and Flame Characteristics
Smoky flame — insufficient air, flue restriction.
Noisy burner — too much air, incorrect input
TROUBLESHOOTING - COOLING SYSTEM
Compressor Does Not Start
Power failure — power switch off; blown line
fuse, defective wiring.
No power to controls ~ thermostat set too low;
or dirty or defective, defective transformer.
— dirty filters;
limit switch set
contactor coil open; loose leads from closed
contactor.
Power to compressor — motor windings open,
contactor closes, then opens
Compressor Runs But Cooling is Insufficient
Low suction pressure — restricted airflow;
capillary tubes restricted; low refrigerant
charge.
Low head and high suction pressure — defective
compressor valves.
Indoor fan stopped — loose or broken leads,
faulty capacitor; internal short circuit
Compressor Does Not Restart
Power failure — power switch off, blown line
fuse
Power at closed contactor — faulty start relay
or capacitor, contactor, run capacitor or com­
pressor, low line voltage (must be within 10%
of nameplate voltage )
Compressor Cycles on Overload
Insufficient condenser air — check condenser
fan position in reference to orifice as in Fig 11.
Condenser air restricted ^ dirty coil, airflow
restricted
Condenser air recirculating — obstruction de­
flecting airflow.
Improper line voltage — circuit overloaded;
loose electrical connections
Faulty run capacitor — capacitor shorted or low
on capacitance (mfd)
Noncondensables in system — moisture or air in
system
System overcharged — high head pressure
causes by excessive refrigerant.
No refrigerant in system — leak in system.
System restricted — capillary tubes restricted or
plugged, kinked tubing, dirty strainer
Fan slipping on motor shaft — setscrews either
loose or missing from fan.
Fan motor bearing seized — lack of oil or
bearing failure.
Fan motor defective — internal short circuit