Air Conditioning System Performance Check
| (1) Attach Gauge Set |
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| (2) Stabilize System |
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| (3) Temperature Check |
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| (4) Visual Check |
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| (5) Gauge Readings |
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SHOULD BE
| 35-45°F See Ambient Temperature Chart . |
| No excess noise; no leaks Free of obstructions Dry; warm to touch Clear or few bubbles Dry; warm to touch; no leaks Dry Dry; cold to touch Dry; cool to touch Dry; cool to touch; no leaks |
| See Pressure Chart
. See Pressure Chart . See Pressure Chart . |
IF...
| Temperature Check is: |
| Too warm, check function of control levers, heater water valve, cooling system and gauge readings. |
| Visual Check Shows: |
| Noisy, check belts, oil level, seals, gaskets, bearing, reed valves. Check gauge readings. Blocked, clean off debris. Plugged, flush with R-12 or replace, Check gauge readings. Frosty, check for restriction or moisture saturation. Check gauge readings. Replace desiccant. Bubbly, foamy or streaky, check reference manual and gauge readings. Frosty or very hot, check for restriction condenser malfunction or R-12 overcharge. Check gauge readings. Frosty, check for moisture or restriction. Check sensing bulb. Check gauge readings. Freezing or warm, check for expansion valve, thermostatic switch or POA/STV or EPR valve malfunction. Check gauge readings. Frosty or warm, check for valve malfunction. Check gauge readings. Frosty or warm, check for restriction, low R-12 charge, or valve malfunction. Check gauge readings. |
| Gauge Readings are: |
| Above or below normal, refer to "Air Conditioning Diagnosis " chart. Above or below normal, refer to "Air Conditioning Diagnosis " chart. Above or below normal, refer to "Air Conditioning Diagnosis " chart. |
Air Conditioning Diagnosis for Systems with insufficient or No Cooling
| Low Side Gauge | High Side Gauge | Auxiliary Gauge (if used)(1) | Other Symptoms(2) | Diagnosis | ||||
|---|---|---|---|---|---|---|---|---|
| NORMAL | 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 and Moisture in System | ||||
| NORMAL | NORMAL | NORMAL | Cools okay in morning, but not during hot part of day. Tiny bubbles in sight glass. Discharge air warm when low side gauge drops into vacuum. |
Excessive Moisture in System | ||||
| NORMAL | NORMAL | - - - - | Thermostatic switch system only: Compressor cycles on and off too rapidly. |
Defective Thermostatic Switch | ||||
| NORMAL to HIGH | NORMAL | - - - - | Thermostatic switch system only: Compressor doesn't turn on soon enough. Discharge air becomes warm as low side pressure builds. |
Misadjusted Thermostatic Switch | ||||
| LOW | LOW | LOW | Bubbles in sight glass. Outlet air slightly cool. |
Low R-12 Charge | ||||
| LOW | LOW | LOW | Sight glass clear. Outlet air very warm or same as outside air temp. |
Excessively Low R-12 Charge | ||||
| LOW | LOW | LOW | Outlet air slightly cool. Sweating or frost at expansion valve. |
Expansion Valve Stuck Closed, Screen Plugged or Sensing Bulb Malfunction | ||||
| LOW | LOW | LOW | Outlet air slightly cool. High side line cool to touch. Sweating or frost on high side. |
Restriction in High Side | ||||
| LOW | HIGH | HIGH | Evaporator outlet pipe cold. Low side goes into vacuum when blower is disconnected. |
POA/STV or EPR Valve Stuck Open | ||||
| HIGH | LOW | LOW | Evaporator outlet pipe warm. Outlet air warm. |
POA/STV or EPR Valve Stuck Closed | ||||
| HIGH | LOW | LOW | Noise from compressor. | Compressor Malfunction (Internal Leak) | ||||
| HIGH | HIGH | HIGH | Outlet air warm. Liquid line very hot. Bubbles in sight glass |
Condenser Malfunction or R-12 Overcharge | ||||
| HIGH | HIGH | HIGH | Outlet air slightly cool. Bubbles in sight glass. |
Large Amount of Air and Moisture in System | ||||
| HIGH | HIGH | HIGH | Outlet air warm. Evaporator and outlet pipe show sweating and frost. |
Expansion Valve Stuck Open | ||||
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