Wait before restarting a compressor

Air Conditioning and Heat Pumps · Air Conditioning Capacity · printed page 215 (PDF page 216)

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Air Conditioning – Wait Before Restarting Air Conditioning – Compressor Compressor – Air Conditioning

Text in the illustration

r refrigerant gas r
low torque compressors require similar pressures on the suction and discharge sides at startup
once they get going, a significant pressure difference is created
if the compressor is turned off and immediately restarted, the compressor can be damaged by trying to push against 225 PSI of pressure
if you wait 5 minutes before restarting, the excess pressure can be equalized through the capillary tube
refrigerant flow
motor rotor
low temperature low pressure refrigerant gas
70 PSI
suction side
high temperature high pressure refrigerant gas
225 PSI
piston
discharge side
oil
crankcase heater
cross section

Generated explanation

A cross section of a refrigerant compressor shows the motor rotor, piston mechanism, oil reservoir, and crankcase heater. Arrows trace low-temperature, low-pressure refrigerant gas entering the suction side at 70 PSI and high-temperature, high-pressure gas leaving the discharge side at 225 PSI. The annotations explain that low-torque compressors require similar suction and discharge pressures at startup and develop a significant pressure difference during operation. Immediately restarting after shutdown can damage the compressor by forcing it to start against high discharge pressure. The illustration recommends waiting five minutes so pressure can equalize through the capillary tube.