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.
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.
