why does my Toyota Highlander AC not blow cold air anymore

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

549 words

Problem Statement

Learn how to diagnose and fix the AC not blowing cold air in Toyota Highlander. Step-by-step guide with diagnostic procedures 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.
•Avoid inhaling refrigerant; use proper safety equipment when handling.

Symptoms

•No cold air blowing from the vents
•AC compressor not engaging
•Increased cabin temperature
•Unusual noises from the AC system
•AC system cycling on and off frequently
•Presence of refrigerant leaks under the vehicle

Diagnostic Steps

1
Check the AC system fuse and relay for continuity using a multimeter.
2
Inspect the AC compressor visually for any signs of damage or wear.
3
Use an OBD-II scanner to check for any related error codes.
4
Verify refrigerant levels using a manifold gauge set to see if it's low.
5
Listen for the sound of the AC compressor engaging when the AC is turned on.
6
Inspect for any visible refrigerant leaks around the AC components.

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
•Manifold gauge set
•Line wrench
•AC refrigerant can
•Fuse puller

Parts Required

•AC fuse (if blown)
•AC refrigerant
•AC compressor (if damaged)

Related Faults

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Diagnostic Steps

1
Check the AC system fuse and relay for continuity using a multimeter.
2
Inspect the AC compressor visually for any signs of damage or wear.
3
Use an OBD-II scanner to check for any related error codes.
4
Verify refrigerant levels using a manifold gauge set to see if it's low.
5
Listen for the sound of the AC compressor engaging when the AC is turned on.
6
Inspect for any visible refrigerant leaks around the AC components.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the vehicle battery for safety.

2. Inspect and Replace AC Fuse/Relay

Locate the fuse box and identify the AC fuse.
Remove the AC fuse with a fuse puller.
Check for a blown fuse; replace it if necessary.
If the fuse is intact, check the relay by swapping with another relay of the same type.

3. Recharge Refrigerant

Connect the manifold gauge set to the low and high-pressure ports.
If refrigerant levels are low, use a refrigerant can to recharge the system.
- Open the low-pressure side valve and add refrigerant until the correct pressure is reached (around 30-40 psi for low side).
Monitor pressures to avoid overcharging.

4. Repair or Replace AC Compressor

If the compressor does not engage, check the electrical connector for corrosion or damage.
If necessary, remove the AC compressor:
- Disconnect the AC lines using a line wrench.
- Unbolt the compressor from the mounting bracket.
Replace with a new compressor and reattach the AC lines, ensuring all seals are replaced.

5. System Leak Test

After repairs, perform a leak test using nitrogen or a refrigerant leak detector.
If no leaks are detected, proceed to vacuum the system for at least 30 minutes to remove moisture.

6. Recharge the AC System Again

After vacuuming, recharge the system with the appropriate refrigerant.
Check for proper operation by turning on the AC and monitoring the temperature output.