how to fix the rear AC not working in my Toyota Highlander Third Generation (2014-2019)?

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

582 words

Problem Statement

Learn how to diagnose and fix rear AC issues in Toyota Highlander (2014-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Affected Component

HVAC

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical components.
•Allow the engine to cool before handling any components related to the AC system.

Symptoms

•Rear AC vents blowing warm air
•Rear AC controls not responding
•Unusual noises from the rear AC unit
•Refrigerant leak detected (if applicable)
•Front AC functioning normally while rear AC is not

Diagnostic Steps

1
Check the rear AC control settings to ensure they are set to the desired temperature and mode.
2
Inspect the rear AC fuse for any signs of damage or failure; replace if necessary.
3
Scan the vehicle’s onboard diagnostic system for error codes related to the HVAC system.
4
Examine the refrigerant levels in the system using a set of gauges to ensure they are within the manufacturer’s specifications.
5
Inspect the rear AC blower motor for functionality by checking for power and ground connections.
6
Check for any obstructions in the rear AC ducts that could impede airflow.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Multimeter
•Socket set
•Torque wrench
•Refrigerant gauge set

Parts Required

•Rear AC fuse (if blown)
•Rear AC blower motor (if faulty)
•Refrigerant (specific type for your vehicle)

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Diagnostic Steps

1
Check the rear AC control settings to ensure they are set to the desired temperature and mode.
2
Inspect the rear AC fuse for any signs of damage or failure; replace if necessary.
3
Scan the vehicle’s onboard diagnostic system for error codes related to the HVAC system.
4
Examine the refrigerant levels in the system using a set of gauges to ensure they are within the manufacturer’s specifications.
5
Inspect the rear AC blower motor for functionality by checking for power and ground connections.
6
Check for any obstructions in the rear AC ducts that could impede airflow.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Disconnect the battery to ensure safety while working on electrical components.

Tools Required:

OBD-II scanner
Multimeter
Socket set
Torque wrench
Refrigerant gauge set

2. Inspect and Replace the Fuse

Locate the fuse box, typically found under the dashboard or in the engine compartment.
Identify the fuse associated with the rear AC system (refer to the owner’s manual for the specific location).
Remove the fuse using a fuse puller and inspect it for continuity.
Replace the fuse with one of the same amperage if it is blown.

3. Test and Replace the Rear AC Blower Motor

Access the rear AC blower motor, usually located under the rear passenger seat or in the rear cargo area.
Disconnect the electrical connector from the blower motor.
Use a multimeter to check for power at the connector while the rear AC is turned on.
If there is power but the motor does not run, replace the blower motor.
Reconnect the motor and ensure it is securely mounted.

4. Recharge the AC System

Connect the refrigerant gauge set to the low and high-pressure service ports of the rear AC system.
Start the engine and turn on the AC to its maximum setting.
Check the pressure readings and compare them to the specifications in the service manual.
If the refrigerant is low, add refrigerant as needed, following the manufacturer's guidelines for type and amount.