What Happens If I Bypass the Heater Core?

Last Updated on January 30, 2022 by Vernon Scott

The heater core is a prime part of the coolant system of your car. It works like a radiator by channeling the excessive heat into the blower fan. As a result, it is the initial source of heat for your car’s heater. But if it stops working for some reason, then things can get pretty uncomfortable.

Driving with a faulty heater core is never an ideal thing to do. It is because the heater core not only provides heat to the compartment but also stops the engine from overheating by taking the excessive heat from it.

However, can you bypass a heater core? What happens if you do it? In this article, we will elaborate on that in detail.

What Are the Signs of a Bad Heater Core?

Before all, let us show you the signs of a faulty heater core. It will help you know that something is wrong with the part.

  • You can smell coolant inside the car.
  • There will be no heat coming from the heater or blower fan.
  • There will be leak signs under your dashboard. For example, you can notice puddles.
  • Your car windows can get fogs.
  • Your engine is overheating, or the coolant level has decreased.

Can You Bypass a Heater Core?

Yes, it is indeed possible to bypass a heater core. But the job is not something to do without any issue. For example, if the car heater core gets any coolant leaks, some people bypass it. The coolant can also spread in the car compartment as a mist that fogs up the window.

Consequences of Bypassing a Heater Core

First of all, you cannot keep a heater core damaged. That will mean that the engine will run with too much heat, which is pretty risky. Meanwhile, we won’t suggest you bypass the heater core as it has some negative effects.

If you bypass the heater core, the coolant will stop flowing through the heater core when your heater is off. However, the coolant can stay in the heater core. As a result, you can’t stop the coolant leak by bypassing the heater core.

Frequently Asked Questions

What Are the Signs of a Clogged-up Heater Core?

If your heater core is clogged up, you will smell something sweet in the car. The blower fan will start blowing cool air while the engine stays hot. Also, your car windows can get fogs.

Why Do I Smell Antifreeze When My Heater is on?

Antifreeze is a part of the coolant. Smelling it into the air after turning on the heater indicates a coolant leak.

Can You Bypass the Heater Control Valve?

Yes, you can. But it is not a recommendation. As you insert the bypass hoses into your car’s coolant system, the coolant will keep going through the heater core. So, you can’t stop any coolant leaking if it happens.


Instead of bypassing your heater core, you should go for proper solutions that totally fix your issue. For example, if your heater core is clogged up, you can try flashing it using compressed air and cleaner.

On the other hand, a bad heater core will need a replacement. In that case, expect to spend a hefty sum behind the parts and the labor. Since most of the dashboard will be removed, it will take a pretty long time too.

I am a Trained HVAC Technician and Author of EmiNick. I have been in the industry for over 10 years and have gained a wealth of knowledge and experience. I have been involved in all aspects of HVAC, from design and installation to repair and maintenance. I am also a certified energy auditor and have experience in conducting energy audits for both residential and commercial customers. In addition to my HVAC experience, I am also a certified home inspector and have conducted many home inspections for both buyers and sellers. Follow Me: Linkedin

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