Friedrich 2007 - Manual (Page 22)

22
Problem Possible Cause Action
Unit cools when
heat is called for
Incorrect wiring Refer to applicable wiring diagram
Defective solenoid coil Check for continuity of coil
Reversing valve fails to shift
Block condenser coil & switch unit to cooling.
Allow pressure to build up in system, then
switch to heating. If valve fails to shift, replace
valve.
Inoperative system switch Check for continuity of system switch
Problem Possible Cause Action
Cooling adequate,
but heating
insuffi cient
Heating capillary tube partially restricted
Check for partially starved outer coil. Replace
heating capillary tube
Check valve leaking internally
Switch unit several times from heating to
cooling. Check temperature rise across
coil. Refer to specifi cation sheet for correct
temperature rise
Reversing valve failing to shift completely;
bypassing hot gas
De-energize solenoid coil, raise head
pressure, energize solenoid to break loose.
If valve fails to make complete shift, replace
valve.
TROUBLESHOOTING CHART — COOLING
Low Suction Pressure High Suction Pressure Low Head Pressure High Head Pressure
Low Load Conditions High Load Conditions Low Load Conditions High Load Conditions
Low Air Flow Across High Air Flow Across Refrigerant System Low Air Flow Across
Indoor Coil Indoor Coil Restriction Outdoor Coil
Refrigerant System Reversing Valve not Reversing Valve not
Overcharged
Restriction Fully Seated Fully Seated
Undercharged Overcharged
Undercharged
Noncondensables (air)
in System
Moisture in System Defective Compressor Defective Compressor
REFRIGERANT SYSTEM DIAGNOSIS – HEATING
HEAT / COOL ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS