1.3.2 Mechanical troubles
1) Not starting
(1) Phenomenon : Compressor is not started but the starting current continues to flow.
(2) Checking
a) Check capacitor. (for a type where a capacitor for compressor starting or operating is used)
b) If there is no trouble, it is judged as lock due to the wear of compressor inside or the damage of lubricating
device. Replace the compressor.
2) Poor compression
(1) Phenomenon : Compressor is at work, but the cooling capacity is weak, the pressure of high pressure side
is low and the pressure of low pressure side is high.
(2) Cause : Damage of valve in compressor inside, damage of connecting rod or crank shaft, or other internal
leak
(3) Checking
a) Stop and then start the condenser fan, and if the pressure of high pressure side does not increase, the
compressor is bad.
b) Measure the temperature of discharge pipe in compressor, and if it is abnormally low temperature (50°C or
less), the compressor is bad.
c) Conduct the pump down test of system to check the compression capacity.
- Power off the product.
- Close the service valve of liquid line. (Rotate the valve rod clockwise to close the valve rod.)
- Start product and observe the suction pressure.
- If compressor is normal by pumping down the system, pressure is kept 0-5 psiG (0-0.35kg/cm
2
.G), and if
the suction pressure increases, the compressor is bad due to the internal leak or valve damage.
(4) The compressor to be assumed as bad compression should be replaced.
If running for a long time in a bad compression condition, abnormal superheat may occur and the
compressor motor is burnt.
- Clean the cycle.
3) Overcurrent flowing while running
Check the working pressure, and if there is no trouble, it is assumed as the compressor bearing damage.
Replace the compressor.
(Excessive refrigerant charging may cause the overcurrent.)
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