how to fix the 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

587 words

Problem Statement

Learn how to diagnose and fix 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 systems.
•Ensure the engine is cool before inspecting the AC system to avoid burns.

Symptoms

•AC blows warm air
•AC compressor not engaging
•Unusual noises from the AC system
•AC control lights not illuminating
•Foul odors from the vents
•Decrease in engine performance when AC is on

Diagnostic Steps

1
Check the AC fuse in the fuse box for continuity.
2
Use an OBD-II scanner to check for any stored error codes related to the AC system.
3
Inspect the AC refrigerant level using a gauge set.
4
Verify the operation of the AC compressor by observing the clutch engagement.
5
Inspect the AC relay for proper function.
6
Check for any visible leaks in the AC lines or at the compressor.

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
•Refrigerant gauge set
•Multimeter
•Fuse puller
•Pliers

Parts Required

•AC fuse (if blown)
•Refrigerant (R-134a or as specified)
•AC relay (if defective)
•AC compressor (if faulty)

Related Faults

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Diagnostic Steps

1
Check the AC fuse in the fuse box for continuity.
2
Use an OBD-II scanner to check for any stored error codes related to the AC system.
3
Inspect the AC refrigerant level using a gauge set.
4
Verify the operation of the AC compressor by observing the clutch engagement.
5
Inspect the AC relay for proper function.
6
Check for any visible leaks in the AC lines or at the compressor.

Solution

1. Preparation

Gather all necessary tools and parts.
Ensure the vehicle is parked on a level surface and the engine is turned off.
Disconnect the battery to avoid electrical shock.

2. Check and Replace the AC Fuse

Locate the fuse box under the dashboard or in the engine compartment.
Identify the AC fuse as indicated in the owner's manual.
Remove the fuse with a fuse puller or pliers.
Inspect it for continuity; replace with an identical fuse if blown.

3. Recharge the AC System

Connect the refrigerant gauge set to the low-pressure service port.
Check the pressure readings; if low, proceed to recharge.
Attach the refrigerant can to the gauge set, ensuring the can is upright.
Open the valve on the refrigerant can while the engine is running and the AC on max.
Monitor the pressure and add refrigerant until it reaches the manufacturer’s specified level.

4. Inspect and Replace the AC Relay

Locate the AC relay in the fuse box based on the owner's manual.
Remove the relay and test for continuity with a multimeter.
If defective, replace it with a new relay of the same specifications.

5. Examine the AC Compressor

Start the engine and turn on the AC.
Observe the AC compressor; the clutch should engage and spin.
If it does not engage, check the electrical connections and replace the compressor if necessary.

6. Fix Any Leaks

Use a UV dye with the refrigerant or a leak detection kit to find leaks.
If leaks are detected, repair or replace the defective components (hoses, seals, or compressor).