Performance Test Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Refer to the applicable warnings and cautions for this system before performing the following operation (Refer to HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to HEATING & AIR CONDITIONING/PLUMBING - CAUTIONS) . Failure to follow the warnings and cautions could result in possible personal injury or death.

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

Connect a tachometer and a manifold gauge set or an A/C recycling/charging station.
Set the mode control to the Recirculation mode, the temperature control to the full cool position, and the blower fan to the highest speed position.
Start the engine and hold the idle at 1,000 RPM with the A/C compressor clutch engaged.
The engine should be warmed up to operating temperature with the doors closed and windows open.
Insert a thermometer in the driver side center panel air outlet and operate the engine for five minutes.
The compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, unplug the wire harness connector from the A/C low pressure switch located on the accumulator. See Fig 1. Place a jumper wire across the terminals of the A/C low pressure switch wire harness connector.

Fig 1: A/C Low Pressure Switch - Typical
Courtesy of DAIMLERCHRYSLER CORP.

1 - A/C LOW PRESSURE SWITCH

2 - ACCUMULATOR

With the compressor clutch engaged, record the air outlet discharge temperature, the discharge pressure (high side service port) and the suction pressure (low side service port). Compare the air temperature at the center panel outlet and the A/C compressor discharge pressure (high side) to the A/C Performance Temperature and Pressure chart.

A/C PERFORMANCE TEMPERATURE AND PRESSURE

Ambient Air Temperature	21° C (70° F)	27° C (80° F)	32° C (90° F)	38° C (100° F)	43° C (110° F)
Air Temperature at Center Panel Outlet	7° C (45° F)	7° C (45° F)	13° C (55° F)	13° C (55° F)	18° C (64° F)
Compressor Inlet Pressure at Service Port (Low Side)	138 to 207 kPa (20 to 30 psi)	172 to 241 kPa (25 to 35 psi)	207 to 276 kPa (30 to 40 psi)	241 to 310 kPa (35 to 45 psi)	276 to 345 kPa (40 to 50 psi)
Condenser Outlet Pressure at Service Port (High Side)	1034 to 1724 kPa (150 to 250 psi)	1379 to 2068 kPa (200 to 300 psi)	1724 to 2413 kPa (250 to 350 psi)	1999 to 2689 kPa (290 to 390 psi)	2413 to 2965 kPa (350 to 430 psi)

If the air outlet temperature fails to meet the specifications in the A/C Performance Temperature and Pressure chart, or if the A/C compressor discharge pressure is high, refer to the A/C Pressure Diagnosis chart.

A/C PRESSURE DIAGNOSIS

Condition	Possible Causes	Correction
Rapid A/C clutch cycling (ten or more cycles per minute).	1. Low refrigerant system charge.	1. See Refrigerant System Leaks . Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
Equal pressures, but the A/C clutch does not engage.	1. No refrigerant in the refrigerant system.	1. See Refrigerant System Leaks . Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
-	2. Faulty fuse.	2. Check the fuses in the power distribution center and the junction block. Repair the shorted circuit or component and replace the fuses, if required. Refer to WIRING DIAGRAM INFORMATION .
-	3. Faulty A/C clutch field coil.	3. See A/C Compressor Clutch . Test the A/C clutch field coil and replace, if required.
-	4. Faulty A/C clutch relay.	4. See A/C Clutch Relay . Test the A/C clutch relay and relay circuits. Repair the circuits or replace the relay, if required.
-	5. Improperly installed or faulty A/C low pressure switch.	5. See A/C Low Pressure Switch . Test the A/C low pressure switch and tighten or replace, if required.
-	6. Faulty A/C high pressure switch (diesel engine application).	6. See A/C High Pressure Switch . Test the A/C high pressure switch and replace, if required.
-	7. Faulty A/C pressure transducer (gasoline engine application).	7. See A/C Pressure Transducer Test the A/C pressure transducer and replace, if required.
-	8. Faulty powertrain control module (PCM) or engine control module (ECM), depending on engine application.	8. Refer to POWERTRAIN DIAGNOSTIC PROCEDURES - DIESEL or POWERTRAIN DIAGNOSTIC PROCEDURES - GAS for testing of the PCM or ECM. Test the PCM or ECM and replace, if required.
Normal pressures, but A/C Performance Test air temperatures at center panel outlet are too high.	1. Excessive refrigerant oil in system.	1. See Refrigerant Oil Level . Recover the refrigerant from the refrigerant system and inspect the refrigerant oil content. Restore the refrigerant oil to the proper level, if required.
-	2. Blend door actuator improperly installed or faulty.	2. See Blend Door Actuator . Inspect the actuator for proper operation and replace, if required.
-	3. Blend-air door inoperative or sealing improperly.	3. See HVAC Housing . Inspect the blend-air door for proper operation and sealing and correct, if required.
The low side pressure is normal or slightly low, and the high side pressure is too low.	1. Low refrigerant system charge.	1. See Refrigerant System Leaks . Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
-	2. Refrigerant flow through the A/C accumulator is restricted.	2. See A/C Accumulator . Replace the restricted accumulator, if required.
-	3. Refrigerant flow through the A/C evaporator is restricted.	3. See A/C Evaporator . Replace the restricted A/C evaporator, if required.
-	4. Faulty A/C compressor.	4. See A/C Compressor . Replace the A/C compressor, if required.
The low side pressure is normal or slightly high, and the high side pressure is too high.	1. A/C Condenser air flow restricted.	1. Check the A/C condenser for damaged fins, foreign objects obstructing air flow through the condenser fins, and missing or improperly installed air seals. Clean, repair, or replace components as required.
-	2. Inoperative radiator cooling fan.	2. Test the radiator cooling fan and replace, if required. Refer to COOLING .
-	3. Refrigerant system overcharged.	3. See Refrigerant System Charge Level . Recover the refrigerant from the refrigerant system. Charge the refrigerant system to the proper level, if required.
-	4. Air in the refrigerant system.	4. See Refrigerant System Leaks . Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.
-	5. Engine overheating.	5. Test the engine cooling system and repair, if required. Refer to COOLING .
The low side pressure is too high, and the high side pressure is too low.	1. Accessory drive belt slipping.	1. Inspect the accessory drive belt condition and tension. Tighten or replace the accessory drive belt, if required. Refer to COOLING .
-	2. Faulty A/C orifice tube.	2. See A/C Orifice Tube . Replace the liquid line, if required.
-	3. Faulty A/C compressor.	3. See A/C Compressor . Replace the A/C compressor, if required.
The low side pressure is too low, and the high side pressure is too high.	1. Restricted refrigerant flow through the refrigerant lines.	1. See Liquid Line, Suction Line and A/C Discharge Line . Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line, if required.
-	2. Restricted refrigerant flow through the A/C orifice tube.	2. See A/C Orifice Tube . Replace the liquid line, if required.
-	3. Restricted refrigerant flow through the A/C condenser.	3. See A/C Condenser . Replace the restricted condenser, if required.