Carrier 50NC Series - 16 Control and Analysis of Breakdowns

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16 - CONTROL AND ANALYSIS OF BREAKDOWNS
Symptom Cause Solution
The evaporation pressure is
very high in relation to the
air inlet
a) Charge excess
b) High air temperature
c) Compressor suction not airtight
d) Cycle reversing valve in middle position
a) Collect refrigerant
b) Verify overheating
c) Verify compressor state and replace
d) Check that the valve is not clogged. Replace if
necessary
The condensation pressure
is very low
a) Gas lack
b) Compressor suction not airtight
c) Cycle reversing valve in middle position
d) Liquid circuit plugging
a) Search for leaks, complete charge
b) Verify compressor state and replace
c) Check that the valve is not clogged. Replace if
necessary
d) Verify the dehydrating fi lter and expansion valve
The condensation pressure is
very high in relation to the air
outlet, high-pressure switch
cut-off
a) Insuffi cient airfl ow
b) Air inlet temperature is very high
c) Dirty condenser (does not exchange)
d) Much refrigerant charge (fl ooded condenser)
e) The condenser fan is broken down
f) Air in the cooling circuit
a) Verify the air circuits (fl ow, fi lter cleanliness...)
b) Verify the control thermostat readjustment
c) Clean it
d) Collect refrigerant
e) Repair
f) Make a vacuum and charge
The evaporation pressure is
too low (low-pressure safety
cut-off )
a) Low fl ow in the evaporator. Air recirculation
b) Frozen evaporator
c) Liquid line as diff erent temperatures at fi lter
inlet and outlet
d) Gas lack
e) Very low condensation pressure
f) Evaporator fan has broken down
a) Verify the air circuits (fl ow, fi lter cleanliness...)
b) Verify defrost
c) Replace fi lter
d) Search for leaks, complete charge
e) The temperature of air or water in the condenser
is very low (air or water fl ow is very high), adjust
the fl ow
f) Repair
The compressor does not
start, does not make noise
(humming)
a) No power
b) The contacts of a control element are open
c) The timing of the anti-cycle short does not
allow the starting
d) Open contact
e) Contactor coil burnt
f) Indoor klixon open
a) Check diff erential, fuses
b) Verify the safety chain of the electronic control
c) Verify electronic control
d) Replace
e) Replace
f) Wait for reactivation, verify current absorbed
The compressor does not start,
motor sounds intermittently
a) Electrical power supply is very low
b) Power cable disconnected
a) Control line voltage and locate voltage drop
b) Verify connections
Repeated compressor starts
and stops
a) Because of high pressure
b) Control diff erential too short (short cycle)
c) Insuffi cient gas, cut-off due to of low pressure
d) Dirty or frosted evaporator
e) The evaporator fan does not work, cuts off
the low-pressure safety
f) Expansion valve damaged or clogged by
impurities (cuts off the low-pressure safety)
g) Dehydrating fi lter clogged (cuts off the low-
pressure safety)
a) Verify charge
b) Increase diff erential
c) Search for leak and reload unit
d) Clean and verify the evaporator air circuit
e) Replace or repair
f) Replace, as well as fi lter
g) Replace
The compressor makes a
noise
a) Loose attachment
b) Oil lack
c) Compressor noise
a) Fix
b) Add oil to the recommended level
c) Replace
Noisy operation a) Unit installed without antivibration protection a) Place base over shock absorbers
The cycle reversing is not
carried out:
- No defrosting
- Does not change winter -
summer cycles
a) Electrical fault
b) Inversion valve coil defective
c) The defrost method not working
d) Cycle reversing valve in middle position
e) Control fault
a) Locate and repair
b) Replace
c) Verify the parameters
d) Tap with the compressor running. Replace if
necessary
e) Locate and repair
Alarm or reading error in the
humidity probe (with enthalpic
control)
a) Dirt in the humidity sensor a) Disassembly the probe encapsule
b) Proceed to clean the sensor with some soft
cotton element and non-abrasive fl uid, without
pressing it
c) Reassemble the casing, checking that the cable
is in contact externally with the metallic mesh