Issue:
This document contains a Pressure and Temperature Symptoms Chart.
Product line:
All Cooling Units.
Environment:
All Product models, all serial numbers.
Cause:
The purpose of this document is to provide a clear communication on what the relationship between pressure, temperature, and the use of Superheat and Subcooling to troubleshoot.
Resolution:
Pressure and Temperature Symptoms Chart:
| Symptoms Exhibited * | Condition Solutions | |||||
| Suction Pressure | Discharge Pressure | Super Heat | Sub Cooling | Comp. Amps | Symptom | Possible Solutions |
| ↓ | ↓ | ↓ | ↓ | ↓ | Light load | Check filter, blower speed tap selected, blower motor, wheel, and capacitor. |
| ↓ | ↓ | ↑ | ↓ | ↓ | Insufficient refrigerant charge; undercharge; leak | Check system for leak(s). Recover refrigerant, repair leak(s), evacuate system to 500 microns, and re-charge with refrigerant. |
| ↓ | ↓ | ↑ | ↑ | - | Restriction in refrigerant circuit | Look for significant temperature difference at point of restriction. Possible incorrect orifice pin (too small) or TXV stuck closed. |
| ↑ | ↑ | ↑ | ↑ | ↑ | Heavy load | Due to excessive air flow across coil or open return duct in unconditioned space. Check blower speed tap setting (too high) and return duct for leakage. |
| ↑ | ↑ | ↓ | ↓ | ↑ | Restricted outdoor coil | Insufficient air flow across Condenser coil. Check cleanliness of coil. Check condenser fan motor, blade, and capacitor. |
| ↑ | ↑ | ↓ | ↑ | ↑ | Excessive refrigerant charge; overcharge | Recover refrigerant from system and weigh in refrigerant |
| ↑ | ↑ | ↓ | ↕ | ↑ | Air and/or Non-condensable in system | Recover refrigerant from system, evacuate system to 500 microns, and weigh in refrigerant. |
| ↑ | ↓ | ↓ | ↓ | - | Over feeding Metering device | Check for proper pin size or loose TXV sensing bulb or TXV stuck open. |
| ↑ | ↓ | ↕ | ↕ | - | Compressor defective | I.E. runs but doesn't pump, abnormally low Amp draw and abnormally high compressor temperature may be indicated. |
| * "Normal" refers to Pressures, Temperatures, and/or values obtained at rated air flow under a given set of conditions and assumes that no changes have been made to factory refrigerant charge. | ||||||
Released for:APC USA
