Heating & Air Conditioning Dodge Pickup R1500

ENGINE COOLING SYSTEM REQUIREMENTS

To maintain the performance level of the heating, ventilation and air conditioning (HVAC) system, the engine cooling system must be properly maintained. The use of a bug screen is not recommended. Any obstructions in front of the radiator or A/C condenser will reduce the performance of the A/C and engine cooling systems.

The engine cooling system includes the radiator, thermostat, radiator hoses and the engine coolant pump. Refer to COOLING for more information before opening or attempting any service to the engine cooling system.

HEATER AND AIR CONDITIONER

A manually controlled single zone type heating-air conditioning system or a manually controlled dual zone type heating-air conditioning system is available on this model.

All vehicles are equipped with a common heater, ventilation and air conditioning (HVAC) housing (Scheme 1) The system combines air conditioning, heating, and ventilating capabilities in a single unit housing mounted within the passenger compartment under the instrument panel. The HVAC housing includes

Scheme 1

1. Blower motor
2. Blower motor resistor block
3. Heater core
4. Evaporator coil
5. Blend door and actuator
6. Defrost door and actuator
7. Mode door and actuator
8. Recirculation door and actuator

Based upon the system and mode selected, conditioned air can exit the HVAC housing through one or a combination of the three main housing outlets: defrost, panel or floor. The defrost outlet is located on the top of the housing, the panel outlet is located on the face of the housing and the floor outlet is located on the bottom of the housing. Once the conditioned air exits the unit housing, it is further directed through molded plastic ducts to the various outlets in the vehicle interior. These outlets and their locations are as follows

1. Defroster Outlet - A single large defroster outlet is located in the center of the instrument panel top cover, near the base of the windshield.
2. Side Window Demister Outlets - There are two side window demister outlets, one is located at each outboard end of the instrument panel top cover, near the belt line at the A-pillars.
3. Panel Outlets - There are four panel outlets in the instrument panel, one located near each outboard end of the instrument panel facing the rear of the vehicle and two located near the top of the instrument panel center bezel.
4. Front Floor Outlets - There are two front floor outlets, one located above each side of the floor panel center tunnel near the dash panel.

OPERATION

The heating and air conditioning systems pulls outside (ambient) air through the cowl opening at the base of the windshield, then into the plenum chamber above the heating, ventilation and air conditioning (HVAC) housing. On models equipped with air conditioning, the air passes through the evaporator coil. Air flow can be directed either through or around the heater core. This is done by adjusting the blend door with the temperature control knob on the A/C-heater control located the instrument panel. The air flow can then be directed from the panel, floor and defrost outlets in various combinations using the mode control knob located on the A/C-heater control. Air flow velocity can be adjusted with the blower speed selector located on the A/C-heater control.

Note. It is important to keep the air intake opening clear of debris. Leaf particles and other debris that is small enough to pass through the cowl opening screen can accumulate within the HVAC housing. The closed, warm, damp and dark environment created within the housing is ideal for the growth of certain molds, mildews and other fungi. Any accumulation of decaying plant matter provides an additional food source for fungal spores, which enter the housing with the fresh intake-air. Excess debris, as well as objectionable odors created by decaying plant matter and growing fungi can be discharged into the passenger compartment during heater-A/C operation if the air intake opening is not kept clear of debris.

The heater and air conditioning systems are blend-air type systems. In a blend-air system, a blend door controls the amount of unconditioned air (or cooled air from the evaporator on models with air conditioning) that is allowed to flow through, or around, the heater core. A temperature control knob determines the discharge air temperature by actuating an electric motor, which operates the blend door. This allows an almost immediate control of the output air temperature of the system.

On all models, the outside air intake can be shut off by selecting the Recirculation Mode with the mode control knob. This will operate a electric actuated recirculation air door that closes off the outside fresh air intake and recirculates the air that is already inside the vehicle.

The air conditioning compressor can be engaged in any mode by pressing the snowflake, A/C on/off button. It can also be engaged by placing the mode control in the mix to defrost positions. This will remove heat and humidity from the air before it is directed through or around the heater core. The mode control knob on the A/C-heater control is used to also direct the conditioned air to the selected system outlets. The mode control switch uses an electric motor to control the mode doors.

The defroster outlet receives airflow from the HVAC housing through the molded plastic defroster duct, which connects to the HVAC housing defroster outlet. The airflow from the defroster outlets is directed by fixed vanes in the defroster outlet grilles and cannot be adjusted. The defroster outlet grilles are integral to the instrument panel top cover.

The side window demister outlets receive airflow from the HVAC housing through the molded plastic defroster duct and two molded plastic demister ducts. The airflow from the side window demister outlets is directed by fixed vanes in the demister outlet grilles and cannot be adjusted. The side window demister outlet grilles are integral to the instrument panel. The demisters direct air from the HVAC housing through the outlets located on the top corners of the instrument panel. The demisters operate when the mode control knob is positioned in the floor-defrost and defrost-only settings. Some air may be noticeable from the demister outlets when the mode control is in the bi-level to floor positions.

The panel outlets receive airflow from the HVAC housing through a molded plastic main panel duct, center panel duct and two end panel ducts. The two end panel ducts direct airflow to the left and right instrument panel outlets, while the center panel duct directs airflow to the two center panel outlets. Each of these outlets can be individually adjusted to direct the flow of air.

The floor outlets receive airflow from the HVAC housing through the floor distribution duct. The front floor outlets are integral to the molded plastic floor distribution duct, which is secured to the bottom of the housing. The floor outlets cannot be adjusted.

The air conditioner for all models is designed for the use of non-CFC, R- 134a refrigerant. The air conditioning system has an evaporator to cool and dehu-midify the incoming air prior to blending it with the heated air. This air conditioning system uses a fixed orifice tube in the liquid line near the condenser outlet tube to meter refrigerant flow to the evaporator coil. To maintain minimum evaporator temperature and prevent evaporator freezing, a evaporator temperature sensor is used. The JTEC control module is programmed to respond to the evaporator temperature sensor input by cycling the air conditioning compressor clutch as necessary to optimize air conditioning system performance and to protect the system from evaporator freezing.

A/C PERFORMANCE

The air conditioning system is designed to remove heat and humidity from the air entering the passen-ger compartment. The evaporator, located in the HVAC housing, is cooled to temperatures near the freezing point. As warm damp air passes over the fins in the evaporator, moisture in the air condenses to water, dehumidifying the air. Condensation on the evaporator fins reduces the evaporators ability to absorb heat. During periods of high heat and humidity, an air conditioning system will be less effective. With the instrument control set to Recirculation mode, only air from the passenger compartment passes through the evaporator. As the passenger compartment air dehumidifies, A/C performance levels rise.

Humidity has an important bearing on the temperature of the air delivered to the interior of the vehicle. It is important to understand the effect that humidity has on the performance of the air condition-ing system. When humidity is high, the evaporator has to perform a double duty. It must lower the air temperature, and it must lower the temperature of the moisture in the air that condenses on the evaporator fins. Condensing the moisture in the air transfers heat energy into the evaporator fins and tubing. This reduces the amount of heat the evaporator can absorb from the air. High humidity greatly reduces the ability of the evaporator to lower the temperature of the air.

However, evaporator capacity used to reduce the amount of moisture in the air is not wasted. Wringing some of the moisture out of the air entering the vehicle adds to the comfort of the passengers. Although, an owner may expect too much from their air conditioning system on humid days. A performance test is the best way to determine whether the system is performing up to standard. This test also provides valuable clues as to the possible cause of trouble with the air conditioning system.

PERFORMANCE TEST PROCEDURE

Review Safety Warnings and Cautions before performing this procedure (Refer to WARNING ) and (Refer to CAUTION - A/C SYSTEM ). Air temperature in test room and on vehicle must be 21° C (70° F) minimum for this 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.

1. Connect a tachometer and a manifold gauge set or A/C recycling/charging station.
2. Set the A/C-heater mode control in the Recirculation Mode position, the temperature control knob in the full cool position, and the blower motor switch to the highest speed position.
3. Start the engine and hold at 1,000 rpm with the A/C compressor clutch engaged.
4. The engine should be warmed up to operating temperature with the doors closed and windows open.
5. Insert a thermometer in the driver side center panel A/C-heater outlet and operate the engine for five minutes.
6. The compressor clutch may cycle, depending upon the ambient temperature and humidity.
7. With the compressor clutch engaged, record the discharge air temperature and the compressor discharge pressure.
8. If the discharge air temperature fails to meet the specifications in the «A/C PERFORMANCE TEMPERATURE»(/dodge/pickup-r1500/1997-2012/remont/general-servicing-all-makes/#heating-air-conditioning) chart, refer to the «PRESSURE DIAGNOSIS»(/dodge/pickup-r1500/1997-2012/remont/general-servicing-all-makes/#heating-air-conditioning__pressure-diagnosis) . PERFORMANCE TEMPERATURE AND PRESSURE A/C PERFORMANCE TEMPERATURE 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) 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)
9. Compare the compressor discharge pressure to the «A/C PERFORMANCE TEMPERATURE»(/dodge/pickup-r1500/1997-2012/remont/general-servicing-all-makes/#heating-air-conditioning) chart. If the compressor discharge pressure is high, see «PRESSURE DIAGNOSIS»(/dodge/pickup-r1500/1997-2012/remont/general-servicing-all-makes/#heating-air-conditioning__pressure-diagnosis) .

PRESSURE DIAGNOSIS

PRESSURE DIAGNOSIS CHART

HEATER PERFORMANCE TEST

Review Safety Warnings and Cautions before performing this procedure (Refer to WARNING ) and (Refer to CAUTION - A/C SYSTEM ).

Check the coolant level, drive belt tension, vacuum line connections, radiator air flow and fan operation. Start engine and allow to warm up to normal temperature.

If vehicle has been run recently, wait 15 minutes before removing cap. Place a rag over the cap and turn it to the first safety stop. Allow pressure to escape through the overflow tube. When the system stabilizes, remove the cap completely.

MAXIMUM HEATER OUTPUT: TEST AND ACTION

Engine coolant is provided to the heater system by two heater hoses. With the engine idling at normal operating temperature, set the temperature control to maximum heat, the mode control to the floor position, and the blower in 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 TEMPERATURE REFERENCE CHART .

TEMPERATURE REFERENCE CHART

TEMPERATURE REFERENCE CHART

Both of the heater hoses should be HOT to the touch (coolant return hose should be slightly cooler than the supply hose). If the coolant return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the heater system. If both heater hoses are cool to the touch, inspect the engine cooling system (Refer to DIAGNOSIS AND TESTING ).

OBSTRUCTED COOLANT FLOW Possible locations or causes of obstructed coolant flow are as follows

1. Pinched or kinked heater hoses.
2. Improper heater hose routing.
3. Plugged heater hoses or supply and return ports at the cooling system connections.
4. Plugged heater core.

If proper coolant flow through the cooling system is verified, and heater outlet air temperature is insufficient, a mechanical problem may exist.

MECHANICAL PROBLEMS Possible causes of insufficient heat due to mechanical problems are as follows

1. Obstructed cowl air intake.
2. Obstructed heater system outlets.
3. Blend door not functioning properly.

TEMPERATURE CONTROL

If the heater outlet air temperature cannot be adjusted with the temperature control knob on the A/C-heater control, the following could require service

1. Blend door binding.
2. Faulty blend door motor.
3. Faulty A/C-heater control.
4. Faulty related wiring harness or connectors.
5. Improper engine coolant temperature.

HEATING AND A/C SYSTEM

The R-134a refrigerant system charge capacity for this vehicle can be found on the underhood Specification Label.

A/C SYSTEM

A/C SYSTEM SPECIFICATIONS

FASTENER TORQUE

FASTENER TORQUE

See also:
• COOLING
• WARNING
• CAUTION - A/C SYSTEM
• REFRIGERANT SYSTEM LEAKS
• A/C COMPRESSOR CLUTCH/COIL
• A/C PRESSURE TRANSDUCER
• POWERTRAIN DIAGNOSTIC PROCEDURES (PART 1)
• POWERTRAIN DIAGNOSTIC PROCEDURES (PART 2)
• BLEND DOOR
• A/C COMPRESSOR
• REFRIGERANT SYSTEM CHARGE
• A/C ORIFICE TUBE
• A/C PERFORMANCE TEMPERATURE
• PRESSURE DIAGNOSIS