Toyota Highlander Third Generation (2014-2019) AC is blowing warm air how to fix

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

613 words

Problem Statement

Learn how to diagnose and fix the AC blowing warm air issue in the 2014-2019 Toyota Highlander. Step-by-step guide with diagnostic and repair instructions.

Affected Component

HVAC

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Allow the engine to cool before opening the AC system to avoid burns.

Symptoms

•AC vents blowing warm air
•AC compressor not engaging
•Unusual noises from the AC system when activated
•Visible refrigerant leaks under the vehicle
•Increased humidity inside the cabin
•AC control lights not functioning correctly

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for any AC-related faults.
2
Inspect the AC compressor visually for signs of damage or leaks.
3
Check the refrigerant level using a manifold gauge set.
4
Test the AC fuse and relay for continuity.
5
Measure the voltage at the AC compressor clutch to see if it is receiving power.
6
Inspect the cabin air filter for blockages that could affect 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
•AC manifold gauge set
•Socket set
•Fuse puller
•Refrigerant kit (R-134a)

Parts Required

•R-134a refrigerant
•AC compressor (if replacement is necessary)
•AC relay and fuse (if faulty)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to check for any AC-related faults.
2
Inspect the AC compressor visually for signs of damage or leaks.
3
Check the refrigerant level using a manifold gauge set.
4
Test the AC fuse and relay for continuity.
5
Measure the voltage at the AC compressor clutch to see if it is receiving power.
6
Inspect the cabin air filter for blockages that could affect airflow.

Solution

1. Preparation

Gather all necessary tools and parts.
Disconnect the battery to ensure safety while working on electrical components.
Allow the engine to cool before starting work.

2. Check and Recharge Refrigerant

Remove the AC manifold gauge set from the refrigerant kit.
Connect the low-pressure side gauge to the low-pressure port on the AC system.
Start the engine and turn on the AC to maximum cool.
Read the pressure on the gauge; if low, proceed to add refrigerant.
Use R-134a refrigerant and add it slowly until the correct pressure is reached.
Disconnect the gauge set and ensure the cap is securely fastened on the low-pressure port.

3. Inspect and Replace AC Compressor

Locate the AC compressor, typically found on the front of the engine near the serpentine belt.
Remove the serpentine belt using a socket wrench to relieve tension on the tensioner.
Disconnect the electrical connector from the compressor.
Remove the refrigerant lines connected to the compressor (use caution to avoid refrigerant exposure).
Unbolt the compressor from its mounting brackets and remove it from the vehicle.
Install the new compressor by reversing the removal steps, ensuring all seals and O-rings are replaced.

4. Replace AC Relay and Fuse (if necessary)

Locate the fuse panel under the dashboard or hood.
Remove the AC fuse and relay using a fuse puller.
Inspect for any visible damage or corrosion.
Install a new relay and fuse that matches the specifications.

5. Reconnect Battery and Test System

Reconnect the battery terminals securely.
Start the vehicle and turn on the AC to check for proper operation.
Monitor for any unusual noises or continued warm air.