Pressure Test

SYMPTOMS DESCRIPTION

Test results	Related symptoms	Probable cause
Driver and passenger's side A/C vent temperatures may vary by approx. 20°F(11°C)or more.	Suction pressure may be low.	Low refrigerant charge. Expansion valve not opening sufficiently
	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.	Significant refrigerant overcharge.
Discharge pressure abnormally high.	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.
Discharge pressure abnormally low.	Suction and discharge pressures equalize rapidly after stopping compressor. Suction pressure higher than normal.	Faulty A/C compressor discharge valve or seal.
Suction pressure abnormally low.	Weak or insufficient airflow.	Restricted blower intake or 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.
	Reduced airflow from vents. Vent temperature is very low.	Condensation freezing on evaporator. Faulty evaporator temp sensor (check DTC). Faulty expansion valve or compressor relay.
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.	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.	One (or both) cooling fan motor inoperative or wires reversed.
Suction and discharge pressures abnormally high.	Compressor clutch remains engaged during off cycle. Pressure relief valve may open.	Insufficient compressor clutch clearance. Compressor relay or circuit problem. Excessive air in system.
Suction and discharge pressures abnormally low.	Suction line from expansion valve to compressor is not cold.	Excessively low refrigerant charge.
	Lack of slight suction pressure variation at 1,500 a 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 (28 - 33°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 compressor turns off.	A/C compressor internal damage (Check for A/C system debris contamination).
Suction and discharge pressures normal (or near normal).	Vent temperature too high.	Slightly low refrigerant charge. Excessive refrigerant oil in system. Heater valve (if equipped) misadjusted. Air mix door sticking, misadjusted or
Suction and discharge pressures normal (or near normal).	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.