why is my Toyota Highlander Fourth Generation (2020-present) AC blowing hot air

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

563 words

Problem Statement

Learn how to diagnose and fix AC blowing hot air in Toyota Highlander (2020-present). Step-by-step guide with symptoms, diagnostics, 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 components.
•Allow the engine to cool before inspecting or working on the AC system.

Symptoms

•AC system blowing hot air
•Poor airflow from the vents
•AC compressor not engaging
•Unusual noises from the AC unit
•Increased cabin temperature
•Warning lights on the dashboard (if applicable)

Diagnostic Steps

1
Check the AC system’s refrigerant level using a manifold gauge set.
2
Inspect the AC compressor for any signs of damage or wear.
3
Examine the cabin air filter for clogs or blockages.
4
Confirm that the AC compressor is engaging when the AC is turned on.
5
Scan the vehicle's onboard diagnostics (OBD-II) for any error codes related to the AC system.
6
Inspect the AC fuses and relays for faults.

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

•Manifold gauge set
•Screwdriver set
•AC refrigerant (R-134a)
•Safety glasses
•Gloves

Parts Required

•Cabin air filter
•AC refrigerant (if low)
•AC compressor (if faulty)

Related Faults

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Diagnostic Steps

1
Check the AC system’s refrigerant level using a manifold gauge set.
2
Inspect the AC compressor for any signs of damage or wear.
3
Examine the cabin air filter for clogs or blockages.
4
Confirm that the AC compressor is engaging when the AC is turned on.
5
Scan the vehicle's onboard diagnostics (OBD-II) for any error codes related to the AC system.
6
Inspect the AC fuses and relays for faults.

Solution

1. Preparation

Gather tools and parts for the repair.
Safety glasses and gloves for personal protection.
Ensure the vehicle is parked on a flat surface and the engine is off.

2. Check Refrigerant Level

Connect the manifold gauge set to the low and high-pressure service ports of the AC system.
Read the pressure levels; if low, proceed to the next step to recharge.

3. Recharge AC System

If refrigerant is low, add the appropriate type of refrigerant (typically R-134a for this model).
Follow the manufacturer's specifications for the amount to add (usually around 1.5-2 lbs).
Monitor the pressure gauge to ensure it reaches the correct range.

4. Inspect and Replace Cabin Air Filter

Locate the cabin air filter compartment, usually behind the glove box.
Remove the glove box by taking out the screws and gently pushing it aside.
Replace the cabin air filter if it appears dirty or clogged.

5. Check AC Compressor Function

Start the engine and turn on the AC to maximum cold.
Observe if the AC compressor engages (the clutch should click). If it does not, further inspection of the compressor and electrical connections is needed.

6. Replace Faulty Components

If the compressor is faulty, disconnect the battery, then remove the compressor from its mounting brackets and disconnect the refrigerant lines.
Install the new compressor, ensuring all connections are tight and leak-free.
Reconnect the battery and recharge the AC system if necessary.