Dodge Ram Truck 1500-2500-3500. Manual — part 2049
Condition
Possible Causes
Correction
The low side pressure is
normal or slightly high, and
the high side pressure is too
high.
1. 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. Refer to Cooling for more
information on air seals. Clean, repair, or replace
components as required.
2. Inoperative cooling fan.
2. Refer to Cooling for more information. Test the
cooling fan and replace, if required.
3. Refrigerant system
overcharged.
3. See Refrigerant System Charge in this group.
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 in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
5. Engine overheating.
5. Refer to Cooling for more information. Test the
cooling system and repair, if required.
The low side pressure is too
high, and the high side
pressure is too low.
1. Accessory drive belt
slipping.
1. Refer to Cooling for more information. Inspect
the accessory drive belt condition and tension.
Tighten or replace the accessory drive belt, if
required.
2. Fixed orifice tube not
installed.
2. See A/C Orifice Tube in this group. Replace
the liquid line, if required.
3. Faulty compressor.
3. See A/C Compressor in this group. Replace
the 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, Suction, and Discharge Line in this
group. 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 fixed orifice tube.
2. See A/C Orifice Tube in this group. Replace
the liquid line, if required.
3. Restricted refrigerant flow
through the condenser.
3. See A/C Condenser in this group. Replace the
restricted condenser, if required.
HEATER PERFORMANCE
Before performing the following tests, refer to Group 7 - Cooling for the procedures to check the engine coolant
level and flow, engine coolant reserve/recovery system operation, accessory drive belt condition and tension, radi-
ator air flow and the fan drive operation. Perform the HVAC System Test (refer to 24 - HVAC Electrical Diagnostics).
If any diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM),
repair as necessary.
MAXIMUM HEATER OUTPUT: TEST AND ACTION
Engine coolant is provided to the heater system through two heater hoses. With the engine idling at normal oper-
ating 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 Refer-
ence chart.
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HVAC - SERVICE INFORMATION
DR/DH
HEATER TEMPERATURE REFERENCE
Ambient Air Temperature
15.5° C
(60° F)
21.1° C
(70° F)
26.6° C
(80° F)
32.2° C
(90° F)
Minimum Air Temperature at
Floor Outlet
62.2° C
(144° F)
63.8° C
(147° F)
65.5° C
(150° F)
67.2° C
(153° F)
If the heater outlet air temperature is below the minimum specification, refer to Group 7 - Cooling. 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. Refer to Group 7 - Cooling for more information.
OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant flow are as follows:
•
Faulty water pump.
•
Faulty thermostat.
•
Pinched or kinked heater hoses.
•
Improper heater hose routing.
•
Plugged heater hoses or supply and return ports at the cooling system connections.
•
Plugged heater core.
If proper coolant flow through the cooling system is verified, and heater outlet air temperature is low, a mechanical
problem may exist.
MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat due to mechanical problems are as follows:
•
Obstructed cowl air intake.
•
Obstructed heater system outlets.
•
Blend-air door(s) or actuator(s) not functioning properly.
•
Faulty blower motor system
•
Faulty A/C-heater control
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be adjusted with the temperature control on the A/C-heater control, the
following could require service:
•
Faulty A/C-heater control.
•
Faulty blend door actuator(s).
•
Faulty, obstructed or improperly installed blend-air door.
•
Faulty related wiring harness or connectors.
•
Improper engine coolant temperature.
DR/DH
HVAC - SERVICE INFORMATION
24 - 197
SPECIFICATIONS
A/C SYSTEM
Item
Description
Notes
A/C Compressor
Saden SD-7 (5.9L engine)
SP-15 PAG oil
Denso 10S17 (3.7L/4.7L/5.7L/8.3L
engines)
ND-8 PAG oil
Freeze–up Control
Evaporator Temperature Sensor
A/C evaporator mounted
High psi Control
A/C pressure transducer
A/C discharge line mounted
Refrigerant Charge Capacity
Refer to the A/C Underhood
Specification Label located in the
engine compartment.
R134a refrigerant
A/C Clutch Coil Draw
2 - 3.9 amps @ 12V ± 0.5V @ 21°
C (70° F)
5.9L engine
3.2 - 3.3 amps @ 12V ± 0.5V @
21° C (70° F)
3.7L/4.7L/5.7L/8.3L engines
A/C Clutch Air Gap
0.41 - 0.79 mm (0.016 - 0.031 in.)
5.9L engine
0.35 - 0.60 mm (0.013 - 0.024 in.)
3.7L/4.7L/5.7L/8.3L engines
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HVAC - SERVICE INFORMATION
DR/DH
SPECIAL TOOLS
A/C SYSTEM
Snap Ring Pliers C-4574 are required to service the
A/C clutch and field coil.
A/C Line Disconnect Tools 7193 are required to service
the A/C liquid and suction lines, A/C accumulator and
the A/C evaporator.
Snap Ring Pliers C-4574
A/C Line Disconnect Tools 7193
DR/DH
HVAC - SERVICE INFORMATION
24 - 199
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