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Pressure and Temperature Symptoms Chart

Published date: 18 July 2020

This document contains a Pressure and Temperature Symptoms Chart.

Product line:
All Cooling Units.

All Product models, all serial numbers.

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. 
Pressure and Temperature Symptoms Chart:
Symptoms Exhibited * Condition Solutions
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.

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