Failure Diagnosis - Lennox CMC 020S Installation, Operating And Maintenance Manual

4.- MAINTENANCE

4.3.- FAILURE DIAGNOSIS

In case of failure or malfunction of the unit, the display on the control panel will show an error or alarm warning which
is explained in the control panel manual. Nevertheless, whenever there is a unit fault, the unit should be shut down and
our service technicians consulted.
FAULT
UNIT DOES NOT START
UNIT STOPS DUE TO HIGH
PRESSURE DURING THE
COOLING CYCLE
UNIT STOPS DUE TO HIGH PRESSU-
RE DURING THE HEATING CYCLE
UNIT STOPS DUE TO LOW
PRESSURE
UNIT STARTS AND STOPS IN
SHORT CYCLES
LOAD AND ABNORMAL NOISE IN
THE COMPRESSOR (SCROLL)
4.3.1.- SAFETY DEVICES
ASTP COMPRESSOR PROTECTION:
This device protects the compressor against high discharge temperatures.
When the temperature reaches critical values, ASTP protection causes
the "Scrolls" to separate. The compressor stops pumping but the motor
continues to run.
- Occasionally, when the compressor stops and starts, there is a metallic noise due to the compressor scrolls. This is
normal.
- Connect high and low pressure gauges and check that the operating pressures are normal.
- Measure electrical consumption for the unit and check that it is close to that indicated on the specifi cation plate.
- Check the electrical consumption of the compressor and the fans against that specifi ed in the physical data sheets.
- In the case of a Heat Pump unit, make a cycle change on the Control Panel, checking that the 4-way valve makes
the change correctly. Check the pressures in the new cycle.
- CL60: Low pressure switch and high pressure switch are reset automatically and if it operates 3 times in one
day, they change to manual reset, through the control unit.
POSSIBLE CAUSES
Fault in the power supply or insuffi cient voltage.
Circuit breakers have opened.
Power cable or control panel cable is defective.
High pressure switch is defective.
Outdoor fan is not working.
Outdoor fan turns in the wrong direction.
Outdoor coil is dirty or clogged for passing air.
Excess refrigerant charge.
The same causes and solutions as the cold cycle but with reference to the coils and indoor fan.
Low pressure switch defective.
Indoor fan is not working.
Indoor fan turns in the wrong direction.
Lack of refrigerant. Leak.
Dirty air fi lter.
Clogged cooling circuit.
Dirty fi lter drier.
Compressor overcharged.
Compressor cuts off due to Klixon.
Lack of refrigerant.
Power supply phases inverted.
(three-phase compressor).
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POSSIBLE SOLUTIONS
Connect the power supply or check the voltage.
Reset.
Inspect and correct.
Check cut-off pressure switch or replace
pressure switch if necessary.
Check for voltage, inspect the motor and turbine
or replace if necessary..
Reverse the power phases.
Inspect and clean.
Remove the charge and charge according to the
data on the rating plate.
Check the cut-off pressure with a pressure gauge
and replace the pressure switch if necessary.
Check for voltage and inspect the motor, turbine
and replace if necessary.
Reverse the power phases.
Correct leak, create vacuum and charge.
Inspect and clean
Inspect and correct or change the fi lter drier.
Inspect suction and discharge pressure values
and correct.
Check input voltage and voltage drop.
Correct leak and replace.
Check and reverse power phases.
Unit with specifi c compressor protection
La unidad incorpora compresor con protección específi ca