my Toyota Highlander Fourth Generation (2020-present) AC is blowing hot air what’s wrong

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

642 words

Problem Statement

Learn how to diagnose and fix AC blowing hot 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.
•Allow the engine to cool before starting any repair work.

Symptoms

•AC system not cooling the cabin
•Increase in cabin temperature
•Unusual noises when AC is turned on
•AC compressor not engaging
•Presence of refrigerant leaks (evident by oily residue)
•Dashboard warning lights related to the AC system

Diagnostic Steps

1
Check the AC control settings and ensure the system is set to 'Max AC' or 'Cool' with the correct temperature settings.
2
Inspect the AC refrigerant level using a pressure gauge to determine if it is low.
3
Verify that the AC compressor is engaging when the system is turned on.
4
Examine the AC system for any visible leaks or signs of damage (hoses, condenser, evaporator).
5
Scan the vehicle’s onboard computer for any trouble codes related to the AC system using an OBD-II scanner.
6
Check the cabin air filter for blockages that may restrict airflow.

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
•AC manifold gauge set
•UV leak detection kit
•Wrench set
•Screwdrivers

Parts Required

•Refrigerant (R-1234yf)
•New AC compressor (if necessary)
•O-rings for AC connections
•Cabin air filter (if needed)

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 control settings and ensure the system is set to 'Max AC' or 'Cool' with the correct temperature settings.
2
Inspect the AC refrigerant level using a pressure gauge to determine if it is low.
3
Verify that the AC compressor is engaging when the system is turned on.
4
Examine the AC system for any visible leaks or signs of damage (hoses, condenser, evaporator).
5
Scan the vehicle’s onboard computer for any trouble codes related to the AC system using an OBD-II scanner.
6
Check the cabin air filter for blockages that may restrict airflow.

Solution

1. Preparation

Gather tools and parts needed for the repair.
Ensure the vehicle is parked on a level surface with the engine off.
Disconnect the battery to ensure safety.

2. Check and Recharge Refrigerant

Tools Required: AC manifold gauge set, refrigerant (R-1234yf).
Connect the low and high sides of the AC manifold gauge to the corresponding service ports.
Check the pressure readings against manufacturer specifications.
If low, proceed to recharge the system:
- Attach the refrigerant can to the low-pressure side.
- Open the can valve and allow refrigerant to flow into the system while the engine is running and the AC is set to max.
- Monitor the gauge to prevent overcharging.

3. Inspect and Replace Components

Tools Required: Wrench set, screwdrivers, new AC compressor or hoses (if needed).
If the compressor is not engaging, check the electrical connections:
- Inspect the wiring and fuses related to the AC compressor.
- Replace any blown fuses or damaged wiring.
If the compressor is faulty:
- Disconnect the AC lines and remove the old compressor.
- Install the new compressor and reconnect the AC lines, ensuring all connections are tight.
- Replace any O-rings to prevent leaks.

4. Check for Leaks

Tools Required: UV leak detection kit, dye (if necessary).
Add UV dye to the AC system if no leaks are visible.
Use a UV light to inspect for leaks around connections and components after running the AC.

5. Reassemble and Test

Reconnect the battery.
Start the vehicle and turn on the AC.
Monitor the system for any unusual noises or performance issues.
Ensure the air blowing from the vents is cool and within manufacturer specifications.