A/C Diagnosis W/Gauges For SYS. W/Insufficient Or No Cooling
A/C DIAGNOSIS W/GAUGES FOR SYS. W/INSUFFICIENT OR NO COOLING
| Low Side Gauge |
High Side Gauge |
Other Symptoms |
Diagnosis |
| NORMAL |
NORMAL |
No or few bubbles in sight glass. High side gauge may go high. Low side gauge does not fluctuate with compressor on/off cycle. |
Some Air & Moisturein System |
| NORMAL |
NORMAL |
Cools okay in morning but not during hot part of day. Bubbles in sight glass. Discharge air warm when low side gauge drops into vacuum. |
Excessive Moisture in System |
| NORMAL |
NORMAL |
Thermostatic sw. sys. only- compressor cycles off & on too rapidly. |
Defective Thermostatic Sw. |
| NORMAL to HIGH |
NORMAL |
Cycling clutch sys only - compressor doesn't turn on soon enough. Discharge air becomes warm as low side pressure rises. |
Misadjusted Thermostatic Sw. orDefective Pressure Sensing Switch |
| LOW |
LOW |
Bubbles in sight glass. Outlet air slightly cool. |
Low R-12 Charge |
| LOW |
LOW |
Sight glass clear. Outlet air very warm. |
Excessively Low R-12 Charge |
| LOW |
LOW |
Outlet air slightly cool. Sweating or frost at expansion valve. |
Expansion Valve Stuck Closed Screen Plugged or Sensing Bulb Malfunction |
| LOW |
LOW |
Outlet air slightly cool. High side line cool to touch. Sweating or frost on high side. |
Restriction on High Side |
| LOW |
HIGH |
Evaporator outlet pipe cold. Low side goes into vacuum when blower is disconnected. |
STV Stuck Open |
| HIGH |
LOW |
Evaporator outlet pipe warm. Outlet air warm. |
STV Stuck Closed |
| HIGH |
LOW |
Noise from compressor. |
Compressor Malfunction |
| HIGH |
HIGH |
Outlet air warm. Liquid line very hot. Bubbles in sight glass. |
Compressor Malfunction or R-12 Overcharge |
| HIGH |
HIGH |
Outlet air slightly cool. Bubbles in sight glass. |
Large Amount of Air of Air & Moisture in System |
| HIGH |
HIGH |
Outlet air warm. Evaporator outlet sweating and frost. |
Expansion Valve Stuck Open |