Why My Car Heater Only Works When Accelerating – Complete Guide

The car heater functions together with the engine’s cooling system of the car. Many car users are experiencing an issue with their heating system working when accelerating, resulting in it failing to function when warm or cold and the user is idling in the car. Sometimes, the car heater may become faulty when still driving.

There are several reasons why the car heater may blow out, and they include; a faulty heater fan, a clogging heater core, among others. The issue affects many users, and there are some ways to solve the problem successfully. For instance, unclog the clogged car heater controls using recommended.

Luckily, the article below describes the steps to follow to bring your heater to correct functioning. Also, it contains additional information, which is of great importance. Make sure you read the whole article and try fixing the issue yourself before seeking help.

Causes of the car heater functioning when accelerating

Causes of the car heater functioning when accelerating

Many factors might wreak havoc on your car heater, causing it to malfunction. They are as follows:

  • The heater’s core is clogged

Although a clogged heater core isn’t one of the most prevalent auto heater issues, it could be the root cause of the problem. The heater core warms your car’s cockpit by using a heated engine coolant from your car’s air conditioning system. You may suffer car heater troubles if this element becomes clogged.

  • A faulty heater control valve

When the heater control system malfunctions, the air combining valves fail to display as an additional option. Check the cold and warm air “mixture” until it is expelled from the air, resulting in very little hot air from the heater pipes.

  • Water leaks

The typical problem with vehicle heaters is a slow leak of water present. There are multiple spills on your floor, so inspect your tube, boiler, and water pump for harm. If one of these three leaks occurs, your car heater will not operate effectively.

  • Presence of openings/air pockets that aren’t working properly

Openings may also be to blame if your heat only works when you’re running. Low coolant or a malfunctioning radiator cap might cause air pockets in the air conditioning system, inhibiting proper coolant flow. On the other hand, insufficient coolant amounts are frequently the cause of poor engine performance, overheating, and inconsistent heat emanating from your cabin ventilation.

  • The thermostat is clogged or broken

The thermostat can become clogged with debris and rusty, preventing it from sealing correctly. If this element is left open, you may notice a drop in engine temperature. The heater will not be capable of developing the necessary warmth if the engine does not warm up as it should due to a stuck open thermostat, causing your car’s heater to stop pumping hot air.

  • Low antifreeze or coolant

If the antifreeze in your car is insufficient and the heater is on, you may discover that the heating only works when you’re running. In this situation, check the coolant level and use the required amount.

Check out the Valvoline Multi-vehicle antifreeze on Amazon

How to repair car heaters that only function when you accelerate

car heater only works when accelerating

Tools necessary;

  • spare car heater control valve
  • protective gloves.
  • A spanner.
  • A new thermostat
  • heater core.
  • Antifreeze.
  • Vacuum cleaner

Check this table;

How to repair car heaters that only function when you accelerate.FunctionEssential tools
Unclog the heating core.To troubleshoot your heater core problemsCheck the heater on Amazon
Unblock the heating controls.To bring your heater control to correct functioning.Vacuum cleaner
Replace the thermostatTo bring the thermostat to functioning.A thermostat
Check the heater control valve on your carTo provide good air conditioning while still acceleratingSpare car heater control valve
Check for water leaks in your carCorrecting the water leaks 

i. Unclog the heating core

Flush your heater channel to remove any dirt blocking the warm airflow and troubleshoot your heater core problems. If flushing does not work, replace the heater core according to the manufacturer’s instructions. Ensure you wear protective gloves before you start the process.

Check out the PetFusion protective gloves on Amazon.

ii. Unblock the heating controls

If you’ve been using your heater control for a long time without changing it, it could be damaged and blocked. Remove the clogging using a Vacuum cleaner or a thin brush to suck all dust present. Your heater control may be in good working order, but it will not operate if the heater core buttons are damaged. To resolve the issue, make sure you replace your heating control button.

If the heater control is operating correctly, look over your heater core for any issues. Fix the problem that causes your automobile to warm up by continuously blowing warm air into the cabin. Finally, when repairing your automobile heater control, make sure you follow the manufacturer’s directions carefully to avoid more damage.

iii. Replace the thermostat

When you accelerate, the thermostat works; however, if your thermostat displays “C” even when you accelerate, you may have damaged your thermostat, which necessitates rapid troubleshooting. If your thermostat fails to function correctly, a signal indicating that the car engine is hot will not be given to the heater core, preventing the car from being heated.

You can either repair or replace your thermostat. The instructions below will help you troubleshoot your thermostat.

  • Stop your car and let it sit for 10 to 20 minutes if your thermostat stops working. Your automobile will cool down if you leave it for these minutes.
  • Locate the thermostat in your vehicle. It exists between the central hose and the core in all cars.
  • To see the thermostat, gently pull the radiator cap off and lift the vehicle’s front end.
  • Remove all of the coolants from the radiator by dismantling the central hose.
  • Slowly remove the thermostat and, if possible, try to repair it. If the thermostat is too faulty, it needs replacement with a new one compatible with your vehicle.
  • Reinstall the primary pipe to the car radiator.
  • Replace the cap on the reservoir and place the coolant properly.
  • Lower your car slowly back to its original position.
  • Turn on your car engine and wait to see any heat emissions.
  • Drive a few miles to see how well your thermostat works. If you can’t fix the thermostat, try attaching it or hiring a local mechanic to install the new thermostat.

Check out the Superstat premium thermostat on Amazon.

iv. Check the heater control valve on your car

Check the heater control valve on your car

Many roles heater control does include; enabling hot water to flow when the power required is more significant than when accelerating. Identify any issues with your car’s control valve first. Lowering the automobile back, for example, removes hot air continually and provides hotter air conditioning while still accelerating.

Depending on the type of valve in your car engine, repair the heat control valve immediately. Remove any damaged parts from the vehicle’s engine. Fix the spare car heater control valve, which is largely manual, and try testing your car heater.

v. Check for water leaks in your car

When your car begins to leak water, the heater will stop working correctly. A powerful and efficient heating system can help you enjoy the cold months. If you can’t get your car’s heat to leave the vents, contact a nearby repair shop to correct the water leaks. Ignoring the problem while driving causes more severe harm than getting a mechanic.

vi. Check the heater control valve on your car

The heater controls many activities, such as enabling hot water to flow when the power required is more significant than accelerating. Identify any issues with your car’s control valve first. Lowering the automobile back, for example, removes hot air continually and provides hotter air conditioning while still accelerating.

Depending on the type of valve in your car engine, the heat control valve needs immediate fixation. Remove any damaged parts from the vehicle’s engine. Fix the spare car heater control valve, which is largely manual, and try testing your car heater.

vii. Check the antifreeze level

If the antifreeze is not working, first check the coolant level and ensure it is high. If the coolant level falls off, warm air becomes faulty, resulting from freezing temperature.

Signs your car heater core is faulty

If you suspect that your heater core is damaged or not working correctly, consider the signs below.

  • Snow inside your car
  • Car coolant functions faster
  • Too much cold inside the car
  • A sweet-smelling scent

You might be interested to read also our another comprehensive article of: Can I Use a Car Battery to Start My Generator? – Complete Guide

Frequently asked questions;

  • What’s the difference between coolant and antifreeze?

No, the terms coolant and antifreeze are interchangeable when it comes to a coolant system. Your coolant or antifreeze, whatever you prefer, has essential qualities that assist protect the engine from overheating and freezing and compounds that help prevent engine rust and grease that help lock and gaskets.

Conclusion

Every car has weaknesses, such as heater cores that operate while accelerating and thermostats that fail. The procedures outlined in this article will assist you in troubleshooting the car heater that only works when you accelerate. Both experts and non-professionals can follow the instructions because they are essential and straightforward.

Professionals generally suggest the steps outlined in this article. So go ahead and use them as you want. In case the issue persists, please seek help from a professional mechanic. Also, remember to service your car often to prevent such problems.

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