TK 61753-2-MM-EN
149
Rapid cycling between cool and heat
Unit cools in heat and defrost cycle
Unit heats in refrigeration cycle
High head pressure
Low head pressure
High suction pressure
Low suction pressure
No suction pressure
Unit operating in a vacuum
Receiver sight glass empty
Suction line frosting back
Unable to pump down system
Unable to pull vacuum in low side
Unable to hold vacuum in low side
Noisy compressor
Unit not refrigerating
Unit not heating or defrosting
SYMPTOM
POSSIBLE CAUSES
• • Restricted line on the low side
• • • •
Restricted line on the high side
• • • • Restricted drier
•
Defrost damper stays open
• • •
Defrost damper stuck closed
•
Evaporator fans stay running
• • •
Evaporator fans not running
• Suction service valve back seated
• • • • • • • •
Faulty three-way valve
• • • • •
Faulty pilot solenoid
• • Loose or broken electrical connections
• • • • • Sensor out of calibration
• • • •
Compound pressure gauge out of calibration
•
Leaky receiver tank outlet valve
•
Leaky bypass check valve
•
Leaky condenser check valve
•
Faulty three-way condenser pressure bypass check
valve
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