Symptom | Condition | Possible Cause | |
| Discharge pressure abnormally high. | Radiator fan air suction poor. | • Fan belt broken or loose. • Condenser and radiator fins covered with dirt and dust. | • Retighten or replace. • Clean condenser and radiator. |
| No bubbles appear in sight glass when condenser is cooled with water. | Excessive refrigerant charged. | Discharge refrigerant to proper amount. | |
| Pressure at high pressure side abnormally high. Just after stopping compressor, pressure drops quickly to about 28psi. | Air entered in refrigerating cycle. | Discharge refrigerant and after sufficient evacuating, recharge refrigerant. | |
| Suction pressure abnormally high. | Abnormally cold around low pressure hose and low pressure side service valve. | • Expansion valve opening too large. • Heat sensitizing tube has poor contact. | Reinstall or replace. |
| Heat load too large. | Outside air temperature abnormally high. | Endeavor to cool the condenser. | |
| High pressure side pressure high but suction pressure drops when condenser is cooled. | Excessive refrigerant charged. | Discharge refrigerant to proper amount. | |
| Just after stopping compressor, high and low pressure side pressures become equal. | • Blow on out gasket. • High and Low pressure valve broken or foreign object lodged in valve. | • Replace. • Replace valve or remove foreign object. | |
| Discharge pressure abnormally low. | • Low pressure side pressure too low. • Low pressure piping not cold. | • Heat sensitizing tube gas leakage. • Expansion valve frozen or defective. | Replace. |
| Large passage of bubbles through sight glass. | Not enough refrigerant. | Charge to proper amount. | |
| If compressor is stopped, high and low pressure side pressures immediately equalize. | Compressor discharge or suction valve broken. Foreign object stuck in compressor discharge valve. | • Repair or replace. • Disassemble and remove. | |
| Suction pressure abnormally low. | Large passage of bubbles through sight glass. | Refrigerant insufficient. | Charge to proper amount. |
| High pressure side pressure too low. Low pressure piping not cold. | • Heat sensitizing tube gas leakage. • Expansion valve frozen or defective. | Replace. | |
| Discharge port temperature low, air not coming out. | Evaporator frosted. | • Adjust stabilizer relay. • Operate correctly (blower speed and temperature control combination.) | |
| Expansion valve frosted. | Expansion valve tends to clog. | Clean (remove moisture) or replace. | |
| Temperature difference at receiver front and rear pipings. When excessive, receiver rear piping frosts. | Receiver clogged. | Replace. | |
| Discharge and suction pressure both high. | Heavy covering of dirt and dust on condenser fins. | Condenser cooling insufficient. | Wash off dirt and dust to improve air passage. |
| No bubbles pass through sight glass when water is poured on condenser. | Refrigerant charged excessively. | Discharge refrigerant to proper quality. | |
| Discharge and suction pressure both low. | Large passage of bubbles through sight glass. | Refrigerant insufficient. | Charge to proper amount. |
| Gas leakage. | Shaft seal becomes noticeably dirty and gaskets leaking. | Gas leaking from shaft seal. | Replace shaft seal. |
| Bolts get stained with oil. | Gas leaking from bolted parts. | Retighten bolts. | |
| Gasket joints get stained with oil. | Gas leaking from gasket joints. | Replace gasket. | |
| Leakage from cracked part. | Gas leaking from part. | Replace cracked part. |
