| Driver and passenger's side A/C vent temperatures may vary by approximately 20°F (11°C) or more |
Suction pressure may be low |
- Low refrigerant charge
- Expansion valve not opening sufficiently
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| Air mix door DTCs present |
One air mix door stuck or inoperative |
| Discharge pressure abnormally High |
- Discharge pressure reduced when A/C condenser cooled with water spray
- With doors open, fresh air selected and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41°F (5°C)
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Significant refrigerant overcharge |
| Restricted/weak airflow through A/C condenser |
- Dirty A/C condenser or damaged fins
- Debris between A/C condenser and radiator
- One or more cooling fans malfunctioning
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| Discharge pressure abnormally Low |
- Suction and discharge pressures equalize rapidly after stopping A/C compressor
- Suction pressure higher than normal
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Faulty A/C compressor discharge valve or seal |
| Suction pressure abnormally Low |
Weak or insufficient airflow across evaporator |
Restricted blower intake or dust and pollen filter |
| Suction pressure varies from near normal to a vacuum, as moisture freezes in expansion valve orifice |
- Moisture in the system
- Faulty expansion valve
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- Reduced airflow from vents
- Vent temperature is very low
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- Evaporator freezing
- Faulty evaporator temperature sensor (check DTC)
- Faulty expansion valve or A/C compressor clutch relay stuck in the on position
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| Suction pressure abnormally High |
- Lack of slight suction pressure variation at 1, 500 rpm when "Recirculated" airflow is switched to "Fresh Air"
- Discharge pressure near normal
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Expansion valve stuck open or open too long |
| Suction and Discharge pressures abnormally High |
- Sheet of paper does not stick to front of A/C condenser surface with cooling fans on
- With doors open, fresh air selected and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41°F (5°C)
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One (or both) cooling fan motors inoperative or wires reversed |
- A/C compressor clutch remains engaged during off cycle
- Pressure relief valve may open
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- Insufficient A/C compressor clutch clearance
- A/C compressor clutch relay stuck in the on position or circuit problem
- Excessive air in system
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| Suction and Discharge pressures abnormally Low |
Suction line from expansion valve to A/C compressor is not cold |
Excessively low refrigerant charge |
| Lack of slight suction pressure variation at 1, 500 rpm when "Recirculated" airflow is switched to "Fresh Air" |
Expansion valve clogged with debris/desiccant, stuck closed, or not opening sufficiently |
| More than 50-60°F (10-16°C) temperature drop across A/C condenser inlet to outlet pipes |
Blocked or restricted A/C condenser internal passages or lines/components restricting refrigerant flow |
| Significant temperature difference along high or low side A/C lines or components NOTE: Some restrictions may not show up until 3, 000 rpm |
Restriction in A/C suction or discharge lines or components (check temperatures to isolate) |
| Suction pressure High and Discharge pressure Low |
- Excessive A/C compressor noise
- Pressures equalize quickly and noise after A/C compressor turns off
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A/C compressor internal damage (Check for A/C system debris contamination) |
| Suction and discharge pressures slightly low |
Vent temperature too high |
- Slightly low refrigerant charge
- Air mix door sticking, misadjusted or inoperative
- Excessive refrigerant oil in system
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| Static pressures high with A/C system equalized. (After engine is off 4-12 hours) |
- Air/Non-condensable gasses in system
- Contaminated or incorrect refrigerant
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