Condition
Possible Causes
Correction
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. Refrigerant flow through
the accumulator is restricted.
2. See Accumulator in this group. Replace the
restricted accumulator, if required.
3. Inoperative radiator cooling
fan.
3. Test the radiator cooling fan and replace, if
required. Refer to Group 7.
4. Refrigerant system
overcharged.
4. See Refrigerant System Charge in this group.
Recover the refrigerant from the refrigerant
system. Charge the refrigerant system to the
proper level, if required.
5. Air in the refrigerant
system.
5. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
6. Engine overheating.
6. Test the engine cooling system and repair, if
required. Refer to Group 7.
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. Replace the accessory drive belt or
tensioner, if required. Refer to Group 7.
2. Faulty A/C orifice tube.
2. See A/C Orifice Tube in this group. Replace
A/C liquid line if required.
3. Faulty A/C 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 Line, Suction Line 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 A/C orifice tube.
2. See A/C Orifice Tube in this group. Replace
A/C liquid line if required.
3. Restricted refrigerant flow
through the A/C 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.
WARNING: Do not remove radiator cap when engine is hot, personal injury can result.
If vehicle has been run recently, wait 15 minutes before removing the radiator 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 pressure sta-
bilizes, remove the cap completely.
MAXIMUM HEATER OUTPUT
Engine coolant is delivered to and from the heater core through two heater hoses. With the engine idling at normal
operating temperature, set the temperature control to the full hot 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 at the front floor outlets. Compare the test thermometer reading to the Heater Temperature Ref-
erence chart.
PM
HVAC - SERVICE INFORMATION
24 - 57