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- central air conditioner faults diagnosis
-
- ( RULE 0 )
- IF complaint is "no cooling"
- AND nothing works
- THEN problem is no control voltage
-
- ( RULE 1 )
- IF problem is no control voltage
- AND control transformer is getting line voltage
- AND control transformer output is zero volts
- THENCON fault is burned out control transformer
-
- ( RULE 2 )
- IF complaint is "no cooling"
- ANDNOT nothing works
- AND indoor fan will run
- THEN problem is in condensing section
-
-
- ( RULE 3 )
- IF problem is in condensing section
- ANDNOT compressor will run
- ANDNOT outdoor fan will run
- ANDNOT line voltage is available to contactor
- THENCON condensing unit main power is off
-
- ( RULE 4 )
- IF problem is in condensing section
- ANDNOT compressor will run
- ANDNOT outdoor fan will run
- AND line voltage is available to contactor
- THEN problem is in contactor
-
- ( RULE 5 )
- IF problem is in contactor
- AND 24 volts is available to contactor coil
- AND contactor coil resistance is infinite ohms
- THENCON contactor coil is open
-
- ( RULE 6 )
- IF problem is in condensing section
- ANDNOT compressor will run
- AND outdoor fan will run
- AND voltage exists across contactor compressor contact
- THENCON fault is contactor compressor contact is open
-
- ( RULE 7 )
- IF problem is in condensing section
- ANDNOT outdoor fan will run
- AND compressor will run
- AND voltage exists across contactor outdoor fan contact
- THENCON fault is contactor outdoor fan contact is open
-
- ( RULE 8 )
- IF problem is in condensing section
- ANDNOT compressor will run
- AND outdoor fan will run
- ANDNOT voltage exists across contactor compressor contact
- ANDNOT compressor common amps are 52 amps
- THEN problem is in compressor
-
- ( RULE 9 )
- IF problem is in compressor
- ANDNOT compressor will run
- AND "R" to "C" resistance is infinity
- ANDNOT "S" to "C" resistance is infinity
- THENCON fault is open compressor run winding
-
- ( RULE 10 )
- IF problem is in condensing section
- ANDNOT compressor will run
- AND outdoor fan will run
- ANDNOT voltage exists across contactor compressor contact
- AND compressor common amps are 52 amps
- THEN problem is in compressor start circuit
-
- ( RULE 11 )
- IF problem is in compressor start circuit
- AND "S" to "C" resistance is infinity
- THENCON fault is open compressor start winding
-
- ( RULE 12 )
- IF problem is in compressor start circuit
- ANDNOT "S" to "C" resistance is infinity
- THEN problem is in compressor capacitor
-
- ( RULE 13 )
- IF problem is in compressor capacitor
- AND discharged capacitor shows infinite resistance
- THENCON fault is open compressor capacitor
-
- ( RULE 14 )
- IF problem is in condensing section
- AND compressor will run
- ANDNOT outdoor fan will run
- ANDNOT voltage exists across contactor outdoor fan contact
- THEN problem is in outdoor fan or capacitor
-
- ( RULE 15 )
- IF problem is in outdoor fan or capacitor
- AND outdoor fan run lead amperage is zero
- THENCON fault is open outdoor fan run winding
-
- ( RULE 16 )
- IF problem is in outdoor fan or capacitor
- ANDNOT outdoor fan run lead amperage is zero
- AND outdoor fan start lead amperage is zero
- ANDNOT discharged capacitor shows infinite resistance
- THENCON fault is open outdoor fan start winding
-
- ( RULE 17 )
- IF problem is in outdoor fan or capacitor
- ANDNOT outdoor fan run lead amperage is zero
- AND outdoor fan start lead amperage is zero
- AND discharged capacitor shows infinite resistance
- THENCON fault is open outdoor fan capacitor
-
- ( RULE 18 )
- IF complaint is "no cooling"
- ANDNOT nothing works
- ANDNOT indoor fan will run
- AND voltage exists across fan relay N.O. contacts
- THEN problem is in fan relay
-
- ( RULE 19 )
- IF problem is in fan relay
- AND voltage exists across fan relay N.O. contacts
- AND relay coil resistance is infinity
- THENCON fault is open relay coil
-
- ( RULE 20 )
- IF problem is in fan relay
- AND voltage exists across fan relay N.O. contacts
- ANDNOT relay coil resistance is infinity
- THENCON fault is relay contact stuck open
-
- ( RULE 21 )
- IF complaint is "no cooling"
- ANDNOT nothing works
- ANDNOT indoor fan will run
- ANDNOT voltage exists across fan relay N.O. contacts
- AND fan high speed lead amperage is 0 amps
- THENCON fault is open indoor fan high speed winding
-
- ( RULE 22 )
- IFNOT complaint is "no cooling"
- ANDNOT complaint is "not enough cooling"
- AND complaint is "none"
- THEN we had best check heating mode
-
- ( RULE 23 )
- IF we had best check heating mode
- AND fan switch is in "auto" position
- ANDNOT indoor fan runs after call for heat
- AND fan low speed lead amperage is 0 amps
- THENCON fault is open indoor fan low speed winding
-
- ( RULE 24 )
- IF complaint is "no cooling"
- ANDNOT nothing works
- ANDNOT indoor fan will run
- ANDNOT voltage exists across fan relay N.O. contacts
- ANDNOT fan high speed lead amperage is 0 amps
- THEN problem is in fan starting circuit
-
- ( RULE 25 )
- IF problem is in fan starting circuit
- AND discharged capacitor shows infinite resistance
- THENCON fault is open indoor fan capacitor
-
- ( RULE 26 )
- IFNOT complaint is "no cooling"
- AND complaint is "not enough cooling"
- ANDNOT indoor section filter is dirty
- THEN problem is in outdoor section
-
- ( RULE 27 )
- IF problem is in outdoor section
- AND complaint is "not enough cooling"
- AND condensing coil is clean
- AND condensing temp < 30 deg. above ambient
- THENCON fault is low system refrigerant charge
-
- ( RULE 28 )
- IFNOT complaint is "no cooling"
- AND complaint is "not enough cooling"
- AND indoor section filter is dirty
- THENCON fault is dirty filter
-
- ( RULE 29 )
- IF problem is in outdoor section
- AND complaint is "not enough cooling"
- ANDNOT condensing coil is clean
- THENCON fault is dirty condensing coil
-
- ( RULE 30 )
- IF problem is in condensing section
- AND compressor will run
- AND outdoor fan will run
- ANDNOT compressor is continuously cycling
- ANDNOT condensing unit main power breaker trips
- AND hi & lo pressures are equal or nearly equal
- THENCON fault is compressor valve failure
-
- ( RULE 31 )
- IFNOT complaint is "no cooling"
- ANDNOT complaint is "not enough cooling"
- ANDNOT complaint is "none"
- AND complaint is "outdoor unit makes knocking noise"
- THENCON fault is broken compressor internal mount
-
- ( RULE 32 )
- IFNOT complaint is "no cooling"
- ANDNOT complaint is "not enough cooling"
- ANDNOT complaint is "none"
- AND complaint is "outdoor unit makes squealing noise"
- AND noise is coming from outdoor fan
- THENCON fault is worn outdoor fan motor bearings
-
- ( RULE 33 )
- IFNOT complaint is "no cooling"
- ANDNOT complaint is "not enough cooling"
- ANDNOT complaint is "none"
- AND complaint is "indoor unit makes squealing noise"
- AND noise is coming from indoor fan
- THENCON fault is worn indoor fan motor bearings
-
- ( RULE 34 )
- IF problem is in condensing section
- AND compressor will run
- AND outdoor fan will run
- ANDNOT compressor is continuously cycling
- AND condensing unit main power breaker trips
- AND condensing unit total current is less than 20 amps
- THENCON fault is faulty condensing unit main power breaker
-
- ( RULE 35 )
- IF problem is in condensing section
- AND compressor will run
- AND outdoor fan will run
- AND compressor is continuously cycling
- AND condensing unit voltage is less than 208 volts
- THENCON fault is low main power voltage
-
- ( RULE 36 )
- IF we had best check heating mode
- AND fan switch is in "auto" position
- AND indoor fan runs after call for heat
- THENCON unit is fine - there are no faults