Toyota Highlander Third Generation (2014-2019) AC not working how to troubleshoot

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

551 words

Problem Statement

Learn how to troubleshoot and fix AC issues in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic steps, tools, 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.
•Wear gloves and eye protection when handling refrigerants.

Symptoms

•No cold air blowing from the AC vents
•AC compressor not engaging
•Unusual noises from the AC system
•AC system blowing warm air
•Dashboard warning lights illuminated

Diagnostic Steps

1
Check the AC system refrigerant level using a pressure gauge.
2
Inspect the AC fuse and relay for continuity.
3
Scan the vehicle's onboard diagnostic system for error codes related to the AC.
4
Inspect the AC compressor for visible damage or leaks.
5
Verify the operation of the AC control module and settings on the dashboard.
6
Check the cabin air filter for clogs or restrictions.

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

•AC manifold gauge set
•Fuse puller or flathead screwdriver
•Refrigerant can with gauge (R-134a refrigerant)
•Visual inspection tools (flashlight)
•Screwdriver (for cabin air filter access)

Parts Required

•Replacement cabin air filter
•AC refrigerant (R-134a)
•AC fuse (if blown)
•AC compressor (if faulty)

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Diagnostic Steps

1
Check the AC system refrigerant level using a pressure gauge.
2
Inspect the AC fuse and relay for continuity.
3
Scan the vehicle's onboard diagnostic system for error codes related to the AC.
4
Inspect the AC compressor for visible damage or leaks.
5
Verify the operation of the AC control module and settings on the dashboard.
6
Check the cabin air filter for clogs or restrictions.

Solution

1. Preparation

Gather all necessary tools and parts.
Disconnect the vehicle's battery to ensure safety during repairs.

2. Check Refrigerant Level

Tools required: AC manifold gauge set.
Connect the gauges to the high and low-pressure service ports.
Read the pressure levels; if they are below the manufacturer's specifications, proceed to recharge the system.

3. Inspect AC Fuse and Relay

Tools required: Fuse puller or flathead screwdriver.
Locate the fuse box (usually under the dashboard or in the engine compartment).
Remove the AC fuse and inspect it for continuity.
Replace if blown. Check the relay by swapping it with a similar relay to test functionality.

4. Recharge AC System

Tools required: Refrigerant can with a gauge (R-134a refrigerant).
Follow the manufacturer's guidelines for the amount of refrigerant to add.
Connect the refrigerant can to the low-pressure port and slowly add refrigerant until the correct pressure is achieved.

5. Inspect AC Compressor

Tools required: Visual inspection tools (flashlight).
Examine the AC compressor for any signs of oil leakage or physical damage.
If the compressor is faulty, it will need to be replaced.

6. Replace Cabin Air Filter

Tools required: Screwdriver (if applicable).
Locate the cabin air filter access door (usually behind the glove compartment).
Remove the old filter, check for debris, and replace it with a new one if dirty.