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11 - CONTROL AND ANALYSIS OF BREAKDOWNS
Symptom
Evaporation pressure very high
in relation with the air inlet
Very low condensation pressure a) Gas lack
Condensation pressure very
high in relation to the air outlet,
high pressostat cutoff
Evaporation pressure too low
(low pressure safety cut-off )
Compressor does not start,
does not make noise (humming)
Compressor does not start,
motor sounds intermittently
Repeated compressor starts
and stops
The compressor makes a noise
Noisy operation
Cycle reversing is not carried
out:
- No defrosting
- Does not change winter -
summer cycles
Alarm or reading error in the
humidity probe (with enthalpic
control)
Cause
a) Charge excess
b) High air temperature
c) Compressor suction not air tight
d) Cycle reversing valve in middle position
b) Compressor suction not air tight
c) Cycle reversing valve in middle position
d) Liquid circuit plugging
a) Insuffi cient air fl ow
b) Air inlet temperature 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) Low fl ow in 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 broken down
a) No power
b) The contacts of a control element are open
c) Timing of anti cycle short does not allow the
starting
d) Open contact
e) Contactor coil burnt
f) Indoor klixon open
a) Electrical power supply very low
b) Power cable disconnected
a) Because of high pressure
b) Control diff erential too short (short cycle)
c) Insuffi cient gas, cut-off because of low pressure
d) Dirty or frosted evaporator
e) The evaporator fan does not work, cuts off the
low pressostat
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) Loose attachment
b) Oil lack
c) Compressor noise
a) Unit installed without antivibration protection
a) Electrical fault
b) Inversion valve coil defective
c) Defrost method not working
d) Cycle reversing valve in middle position
e) Control fault
a) Dirt in the humidity sensor
Solution
a) Collect refrigerant
b) Verify overheating
c) Verify compressor state and replace
d) Check that the valve is not clogged. Replace if
necessary
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
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 vacuum and charge
a) Verify the air circuits (fl ow, fi lter cleanliness...)
b) Verify defrost
c) Replace fi lter
d) Search for leaks, complete charge
e) Temperature of air or water in condenser very
low (air or water fl ow very high), adjust fl ow
f) Repair
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
a) Control line voltage and locate voltage drop
b) Verify connections
a) Verify charge
b) Increase diff erential
c) Search for leak, reload unit
d) Clean, verify evaporator air circuit
e) Replace or repair
f) Replace, as well as fi lter
g) Replace
a) Fix
b) Add oil to recommended level
c) Replace
a) Place base over shock absorbers
a) Locate and repair
b) Replace
c) Verify parameters
d) Tap with running compressor. Replace if
necessary
e) Locate and repair
a) Disassembly the probe encapsule.
Proceed to clean the sensor with some soft
cotton element and non-abrasive fl uid, without
pressing it.
Reassemble the casing, checking that the
cable is in contact externally with the metallic
mesh.
21
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