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Home/Cars/Volkswagen/Golf/MK8.5 (2024-Present)/my Volkswagen Golf MK7 (2015-2019) heater only blows cold air what could be wrong?

my Volkswagen Golf MK7 (2015-2019) heater only blows cold air what could be wrong?

Volkswagen Golf MK8.5 (2024-Present)

Severity: mediumDifficulty: medium2-4 hours
3 min read
511 words

Problem Statement

Learn how to diagnose and fix the heater blowing cold air in Volkswagen Golf MK7 (2015-2019). Step-by-step guide with symptoms, diagnostic steps, and repair instructions.

Component
HVAC
Repair Time
2-4 hours

Safety Warnings

  • ⚠Allow engine to cool before opening radiator or working on coolant system.
  • ⚠Disconnect battery before working on electrical components.

Symptoms

  • •Heater blows cold air regardless of temperature setting
  • •Engine temperature gauge remains low or fluctuates
  • •No hot air circulation from vents
  • •Possible coolant leak or low coolant level
  • •Foggy windows due to inadequate defrosting

Diagnostic Steps

  1. 1Check the coolant level in the reservoir and ensure it is within the recommended range.
  2. 2Inspect for any visible coolant leaks under the vehicle or around the engine bay.
  3. 3Scan the vehicle's OBD-II system for any error codes related to the climate control system or engine temperature.
  4. 4Verify that the engine reaches normal operating temperature after a short drive.
  5. 5Test the operation of the heater control valve to ensure it opens and closes correctly.
  6. 6Inspect the thermostat for proper function to ensure it is not stuck open.

Solution

Solution

1. Preparation

  • Gather tools and parts required for the repair.
  • Disconnect the battery to ensure safety while working on the cooling system.

2. Check Coolant Level

  • Open the hood and locate the coolant reservoir.
  • If low, add the appropriate type of coolant (G12 or G13 for Volkswagen).
  • Check for leaks; if leaks are present, replace the damaged hoses or components.

3. Inspect and Replace the Thermostat

  • Remove the engine cover if necessary to access the thermostat.
  • Drain the coolant from the radiator using a drain pan.
  • Disconnect the hoses connected to the thermostat housing.
  • Remove the thermostat and replace it with a new one, ensuring correct orientation.
  • Reconnect hoses and refill the cooling system with the appropriate coolant.

4. Test Heater Control Valve

  • Locate the heater control valve, typically near the firewall.
  • Disconnect electrical connector and hoses from the valve.
  • Use a multimeter to check for electrical continuity (if applicable).
  • Replace the heater control valve if it fails to operate properly.

5. Finalize and Refill

  • Refill the cooling system with coolant to the proper level.
  • Start the engine and let it reach operating temperature while checking for leaks.
  • Bleed the cooling system to remove any trapped air.

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
  • Socket set
  • Torque wrench
  • Multimeter
  • Drain pan

Parts Required

  • Thermostat
  • Heater control valve (if necessary)
  • Coolant (G12 or G13)

Additional Information

Component

HVAC

Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

5 items

Parts

3 items

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