Heating & Air Conditioning - Service Information: Diagnosis RAM Pickup 2500

A/C PERFORMANCE TEST

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.

Note. The work area ambient temperature must be above 21° C (70° F) and the evaporator temperature must be above 13° C (55° F) prior to conducting the A/C Performance Test.

1. Conduct the A/C System Performance Test (Cool down Test) found within the HVAC System Test. Refer to «STANDARD PROCEDURE»(ref-457876-S41951374432012030200000) for ATC or «STANDARD PROCEDURE»(ref-457874-S02669228202012030200000) for MTC . If no Diagnostic Trouble Codes (DTCs) are found in the A/C-heater control, Totally Integrated Power Module (TIPM), Powertrain Control Module (PCM) or Engine Control Module (ECM), depending on engine application. Refer to 2 . If any DTCs are found, repair as required. Refer to 2 .
2. Connect a tachometer and a manifold gauge set or an A/C recycling/charging station.
3. Operate the heating-A/C system under the following conditions. Engine at 1,000 rpm at operating temperature Door and windows closed Transmission in Park or Neutral with parking brake set (depending on transmission application) A/C-heater controls set to recirculation mode (max A/C), full cool, panel mode, high blower and with A/C compressor engaged. If the A/C compressor does not engage, see «A/C SYSTEM DIAGNOSIS»(ref-457787-S06071061992012030200000) .
4. Insert a thermometer in the driver side center panel air outlet and operate the A/C system until the thermometer temperature stabilizes. NOTE: This procedure requires the technician to know what the temperature and relative humidity is at the time of the test. The temperature must be combined with the relative humidity to calculate the apparent ambient temperature ("feels like" temperature), when the temperatures are above 21° C (70° F). Use the current ambient temperature and the relative humidity in your location. This information can be obtained from multiple sources, such as the Internet or local news media.
5. With the A/C clutch engaged, 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. The A/C clutch may cycle, depending upon the ambient temperature and humidity. If the A/C clutch cycles, use the readings obtained before the clutch disengaged (coldest temperature). A/C PERFORMANCE TEMPERATURE AND PRESSURE Ambient Air Temperature (Apparent) 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) Compressor Discharge 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)
6. See the A/C System Diagnosis table below 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.

A/C SYSTEM DIAGNOSIS

MAXIMUM HEATER OUTPUT: TEST AND ACTION

Engine coolant is provided to the heater system through two heater hoses. With the engine idling at normal operating temperature, set the temperature control to maximum heat position, the mode control to the floor position, and the blower motor control to the highest speed position. Using a test thermometer, check the temperature of the air being discharged from the floor outlets. Compare the test thermometer reading to the Heater Temperature Reference chart.

HEATER TEMPERATURE REFERENCE

See ENGINE COOLING SYSTEM if the heater outlet air temperature is below the minimum specification. Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system.

DIAGNOSIS AND TESTING - BLOWER MOTOR RESISTOR

Note. See appropriate Wiring Information for circuit descriptions and diagrams. Wiring Information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.

1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector from the blower motor resistor. Refer to «RESISTOR, Blower Motor , Removal»(ref-457787-S09262524832012030200000) .
3. Using an ohmmeter, check for continuity between all of the blower motor resistor terminals. In each case there should be continuity. If OK, repair the wire harness circuits between the blower motor speed control and the blower motor resistor or blower motor as required. If not OK, replace the inoperative blower motor resistor.

DIAGNOSIS AND TESTING - BLOWER MOTOR

Note. The blower motor is supplied with a 12V fused feed from the TIPM, whenever the ignition switch is in the RUN position. Due to an open circuit condition within the blower motor control switch the TIPM is UNABLE to detect an OPEN circuit for the blower motor.

To determine if an open condition exists within the blower motor circuit wiring, it is necessary to disconnect the negative battery cable and check for continuity within the blower motor circuits using an ohmmeter. See appropriate Wiring Information for circuit descriptions and diagrams.

DIAGNOSIS AND TESTING

Note. If the A/C system refrigerant charge is empty or low, a leak in the A/C system is likely. When searching for a refrigerant leak in the A/C system, use an electronic leak detector and refrigerant leak detection dye with an Ultra Violet (UV) light that is designed for R-134a refrigerant. It is important to use only high-quality refrigerant leak detection equipment to properly locate refrigerant system leaks, such as the equipment listed in the teamPSE Service Equipment Catalog. Use only Chrysler approved R-134a leak detection dye, available through Mopar®.

1. Visually inspect all A/C lines, A/C fittings and A/C components under the hood for an oily residue. Oil residue can be an indicator of a leak location.
2. Connect a high-quality manifold gauge set or refrigerant recovery machine to the A/C system and determine if the static A/C system pressure is above or below 345 kPa (50 psi). Refer to «Plumbing , Standard Procedure»(ref-457787-S01365783702012030200000) . If static A/C system pressure is less than 345 kPa (50 psi), proceed to «SYSTEM EMPTY»(ref-457787-S41589795282012030200000) . If static A/C system pressure is greater than 345 kPa (50 psi), refer to «SYSTEM LOW»(ref-457787-S16521265852012030200000) .

LEAK TEST

1. Position the vehicle in a wind-free work area. This will aid in detecting small leaks.
2. Operate the heating and A/C system with the engine at idle under the following conditions for at least 15 minutes. Doors or windows open Transmission in Park or Neutral with the parking brake set (depending on transmission application) Front A/C and heater controls set to outside air, full cool, panel mode, high blower and A/C compressor engaged If equipped, rear A/C and heater controls set to full cool and high blower.
3. Shut the vehicle off and wait at least 5 minutes. CAUTION: Use it is important to use only a high-quality Ultra Violet (UV) light when searching for a leak in the refrigerant system. Small leaks may not be found using budget equipment. Failure to follow these instructions may result in an incomplete diagnosis and possible remaining refrigerant leaks.
4. Begin searching for leaks using a high quality UV light to detect the fluorescent R-134a leak detection dye. Inspect all connections, plumbing fittings, brazed joints, hoses, hose crimps, service ports, compressor housing, pressure relief valve and A/C condenser for dye. Inspect the evaporator drain tube and condensate for presence of dye, which indicates a leak from the A/C evaporator. WARNING: Use extreme care when working around a running engine. Keep hands and fingers clear of the radiator fan, accessory drive belt and all other moving components. Keep away when wearing loose clothing, jewelry or long hair that is not properly secured. Underhood components may become hot to the touch. Be careful not to come into contact with hot engine, A/C and engine cooling system components. Failure to follow these instructions may result in serious or fatal injury. CAUTION: Use only an electronic leak detector designed for R-134a refrigerant. It is important to use only high-quality refrigerant leak detection equipment. Small leaks may not be found using budget equipment. Failure to follow these instructions may result in an incomplete diagnosis and possible remaining refrigerant leaks.
5. If a leak is not found with the R-134a detection dye, use a high-quality electronic R-134a leak detector and insert it into the evaporator drain tube, and into the instrument panel air outlets, to check for evaporator leaks. Check the evaporator tubes at the A/C expansion valve, for leaks not visible behind the valve. Check around the front of the A/C compressor, for compressor shaft seal leaks. Check between the A/C condenser and radiator for condenser leaks not previously visible.

COIL RESISTANCE TEST

1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector from the A/C clutch coil connector.
3. Use an ohm meter and Back Probe Tool (special tool #6801, Terminal Probe) and measure the resistance of the A/C clutch coil at the coil connector terminals.
4. See A/C Clutch Coil Specifications table for acceptable A/C clutch coil resistance. Specifications apply for a work area temperature of 21° C (70° F). If the A/C clutch coil reading is below specifications, the coil is shorted and must be replaced. If the A/C clutch coil reading is above specifications, the coil is open and must be replaced.

COIL CURRENT DRAW TEST

1. Verify the battery state of charge.
2. Connect an ammeter (0 to 10 ampere scale selected) in series with the A/C clutch coil feed terminal using Back Probe Tool (special tool #6801, Terminal Probe). Connect a voltmeter (0 to 20 volt scale selected) to measure voltage across the battery and the A/C clutch coil.
3. With the A/C-heater control in the A/C mode and the blower motor at low speed, start the engine and allow it to run at a normal idle speed.
4. The A/C clutch should engage immediately and the clutch coil supply voltage should be within two volts of the battery voltage. If the clutch coil supply voltage is OK refer to 5 . If the coil supply voltage is not within two volts of battery voltage, test the clutch coil feed circuit for excessive voltage drop and repair as necessary.
5. See A/C Clutch Coil Specifications table for acceptable A/C clutch coil current draw. Specifications apply for a work area temperature of 21° C (70° F). If voltage is more than 12.5 volts, add electrical loads by turning on electrical accessories until voltage reads below 12.5 volts. If the A/C clutch coil current reading is zero, the coil is open and must be replaced. If the A/C clutch coil current reading is above specifications, the coil is shorted and must be replaced.

A/C CLUTCH COIL SPECIFICATIONS

STANDARD PROCEDURE - A/C CLUTCH INSPECTION

Note. The A/C clutch can be serviced in the vehicle. The refrigerant system can remain fully-charged during compressor clutch, pulley and bearing assembly, or coil replacement.

Scheme 10

Examine the friction surfaces of the pulley and the clutch plate (2) for wear. The pulley and clutch plate should be replaced if there is excessive wear or scoring.

If the friction surfaces are oily, inspect the shaft and nose area of the A/C compressor (1) for refrigerant oil. If refrigerant oil is found, the compressor shaft seal is leaking and the A/C compressor must be replaced.

Check the pulley bearing for roughness or excessive leakage of grease. Replace the pulley and bearing assembly, if required.

DIAGNOSIS AND TESTING - A/C EXPANSION VALVE

Note. The A/C expansion valve should only be tested following testing of the A/C compressor.

Note. Liquid CO 2 is required to test the A/C expansion valve. This material is available from most welding supply facilities. Liquid CO 2 is also available from companies which service and sell fire extinguishers.

When testing the A/C expansion valve, the work area and the vehicle temperature must be 21° to 27°C (70° to 85°F). To test the expansion valve

1. Connect a charging station or manifold gauge set to the refrigerant system service ports. Refer to «Plumbing , Standard Procedure»(ref-457787-S01365783702012030200000) .
2. Verify the refrigerant system charge level by conducting the A/C Performance Test. Refer to «Diagnosis and Testing»(ref-457787-S09173920312012030200000) .
3. Close all doors, windows and vents to the passenger compartment.
4. Set the A/C-heater controls so that the A/C compressor is operating, the temperature control is in the highest temperature position, the mode-air doors is directing air output to the floor and the blower motor operating is operating at the highest speed.
5. Start the engine and allow it to idle. After the engine has reached normal operating temperature, allow the passenger compartment to heat up. This will create the need for maximum refrigerant flow into the A/C evaporator.
6. If the refrigerant charge is sufficient, the discharge (high pressure) gauge should read 827 kPa to 1655 kPa (120 psi to 240 psi). The suction (low pressure) gauge should read 207 kPa to 345 kPa (30 psi to 50 psi). If OK, refer to 7 . If not OK, replace the inoperative A/C expansion valve. WARNING: Protect the skin and eyes from exposure to liquid CO 2 or personal injury can result.
7. If the suction (low pressure) gauge reads within the specified range, freeze the A/C expansion valve for 30 seconds using liquid CO 2 or another suitable super-cold material. Do not spray R-134a or R-12 refrigerant on the A/C expansion valve for this test. The suction (low pressure) gauge reading should drop by 69 kPa (10 psi). If OK, refer to 8 . If not OK, replace the inoperative A/C expansion valve. Refer to «VALVE, A/C Expansion , Removal»(ref-457787-S13706021712012030200000) .
8. Allow the A/C expansion valve to thaw. The suction (low pressure) gauge reading should stabilize at 207 kPa to 345 kPa (30 psi to 50 psi). If not OK, replace the inoperative A/C expansion valve. Refer to «VALVE, A/C Expansion , Removal»(ref-457787-S13706021712012030200000) .