why does my Toyota Highlander Third Generation (2014-2019) AC blow hot air instead of cold

Toyota Highlander Third Generation (2014-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

558 words

Problem Statement

Learn how to diagnose and fix AC blowing hot air 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.
•Allow the engine to cool before inspecting the AC components.

Symptoms

•AC compressor does not engage
•Warm air blowing from vents
•AC control lights not functioning
•Unusual noises from the AC compressor
•Refrigerant leak detected
•High cabin temperature despite AC being turned on

Diagnostic Steps

1
Check the AC system for any blown fuses using a multimeter.
2
Inspect the AC compressor for engagement when the AC is turned on.
3
Measure the refrigerant pressure using a manifold gauge set.
4
Examine the AC condenser for blockages or damage.
5
Verify the operation of the AC control module and temperature sensors.
6
Inspect for refrigerant leaks around hoses and connections.

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
•Manifold gauge set
•Multimeter
•Flashlight
•Basic hand tools

Parts Required

•AC refrigerant (R-134a)
•AC compressor (if needed)
•AC condenser (if needed)
•Fuses (if blown)

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Diagnostic Steps

1
Check the AC system for any blown fuses using a multimeter.
2
Inspect the AC compressor for engagement when the AC is turned on.
3
Measure the refrigerant pressure using a manifold gauge set.
4
Examine the AC condenser for blockages or damage.
5
Verify the operation of the AC control module and temperature sensors.
6
Inspect for refrigerant leaks around hoses and connections.

Solution

1. Preparation

Gather tools: OBD-II scanner, manifold gauge set, multimeter, flashlight, and basic hand tools.
Disconnect the negative battery terminal to ensure safety during repairs.

2. Inspect and Replace Blown Fuses

Locate the fuse box under the dashboard and/or engine compartment.
Use a multimeter to check for continuity in the fuse related to the AC system.
If a fuse is blown, replace it with a new one of the same amperage.

3. Check and Recharge Refrigerant

Connect the manifold gauge set to the low and high-pressure ports.
Check the pressure readings; if low, it indicates a refrigerant leak or insufficient charge.
If necessary, evacuate the system using a vacuum pump and recharge with the correct type and amount of refrigerant (R-134a).

4. Inspect the AC Compressor

Start the engine and turn on the AC to the maximum setting.
Observe the AC compressor; it should engage. If it doesn't:
- Check the electrical connections for corrosion or damage.
- Replace the AC compressor if it fails to engage after verifying circuits.

5. Examine the AC Condenser

Visually inspect the AC condenser for debris or blockages.
Clean the condenser fins using compressed air or a soft brush if blocked.
If damaged, replace the condenser with a new unit.

6. Test the System

After repairs, reconnect the negative battery terminal.
Start the engine and run the AC to check for proper operation.
Monitor the temperature from the vents to ensure it is blowing cold air.