Pinpoint Test Y: Insufficient Air Conditioning (A/C) Cooling
Climate Control System
Pinpoint Tests
Pinpoint Test Y: Insufficient Air Conditioning (A/C) Cooling
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the solenoid and manifold assembly receives a ground from the HVAC module - Dual Automatic Temperature Control (DATC) through circuit RH226 (WH/VT). When the heater control valve vacuum solenoid is to be energized, the solenoid and manifold assembly receives voltage from the HVAC module - DATC through circuit CH224 (BU/OG).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Solenoid and manifold assembly
- HVAC module - DATC
- Manual climate control assembly
- Heater control valve
- Stuck or bound linkage or door
- Leaking or plugged vacuum hose
PINPOINT TEST Y: INSUFFICIENT AIR CONDITIONING (A/C) COOLING
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Y1 CHECK FOR COOLANT FLOW TO THE HEATER CORE
- Run the engine until it reaches normal operation temperature.
- Press the PANEL, RECIRC and A/C buttons on the HVAC module - DATC or select MAX A/C on the function selector switch. Set the temperature control to full COOL.
- Using a suitable temperature measuring device, check the heater core inlet hose to see if it is hot.
- Is the heater core inlet hose hot?
Yes
GO to Y2.
No
GO to Refrigerant System Tests Refrigerant System Tests.
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Y2 CHECK FOR VACUUM AT THE HEATER CONTROL VALVE
- Disconnect the heater control valve vacuum connector and check for vacuum.
- Is vacuum present at the heater control valve?
Yes
INSTALL a new heater control valve. TEST the system for normal operation.
No
GO to Y3.
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Y3 CHECK THE HEATER CONTROL VALVE VACUUM LINE FOR BLOCKAGE
- Ignition OFF.
- NOTE: Manual climate control systems only.
- Disconnect the function selector switch vacuum connector. Connect the vacuum pump to the heater control valve vacuum line and attempt to pull a vacuum.
- NOTE: DATC systems only.
- Disconnect the solenoid and manifold assembly vacuum connector. Connect the vacuum pump to the heater control valve vacuum line and attempt to pull a vacuum.
- Can a vacuum be pulled on the heater control valve vacuum line?
Yes
INSTALL a new vacuum harness. TEST the system for normal operation.
No
GO to Y4.
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Y4 CHECK THE HEATER CONTROL VALVE VACUUM LINE FOR LEAKS
- Plug the heater control valve vacuum line at the heater control valve connection.
- NOTE: Manual climate control systems only.
- Leak test the heater control valve vacuum line, using the vacuum pump.
- NOTE: DATC systems only.
- Leak test the heater control valve vacuum line, using the vacuum pump.
- Does the heater control valve vacuum line leak?
Yes
INSTALL a new vacuum harness. TEST the system for normal operation.
No
GO to Y5.
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Y5 CHECK FOR INCORRECT VACUUM LINE PLACEMENT
- Ignition OFF.
- Inspect the heater control valve and A/C vacuum lines for correct placement.
- Is the vacuum line placement correct?
Yes
Manual climate control systems, INSTALL a new climate control assembly. TEST the system for normal operation.
DATC systems, GO to Y6.
No
CORRECT the vacuum line placement. TEST the system for normal operation.
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Y6 CHECK THE SOLENOID AND MANIFOLD ASSEMBLY CIRCUIT VOLTAGE
- Connect the vacuum harness connector to the solenoid and manifold assembly.
- Ignition ON.
- Press the PANEL, RECIRC and A/C buttons on the HVAC module - DATC.
- NOTE: The following measurement must be taken by back-probing the solenoid and manifold assembly C2093.
- Measure the voltage between solenoid and manifold assembly C2093-1, circuit RH226 (WH/VT), harness side and C2093-6, circuit CH224 (BU/OG), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new solenoid and manifold assembly. TEST the system for normal operation.
No
GO to Y7.
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Y7 CHECK THE SOLENOID AND MANIFOLD ASSEMBLY CIRCUIT CH224 (BU/OG) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228b.
- Disconnect: Solenoid and Manifold Assembly C2093.
- Measure the resistance between HVAC module - DATC C228b-14, circuit CH224 (BU/OG), harness side and solenoid and manifold assembly C2093-6, circuit CH224 (BU/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new HVAC module - DATC. TEST the system for normal operation.
No
REPAIR circuit CH224 (BU/OG) for an open. TEST the system for normal operation.
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