How To Flush Car Heater Core? 5 Easy Steps!

Are you wondering how to flush car heater core because you can’t bear a cold car anymore? Don’t worry because we have a solution for you. We have compiled this guide on draining a heater core to derive the maximum heater from your car heater.

The heater is an essential part of a car, and its maintenance becomes obligatory in the winter as no one wants to drive the car with freezing hands. So, it’s better to have some energy and fix the heater yourself rather than calling a mechanic and paying him a handful of bucks. 

how to flush car heater core

My friends, there are more things that you should know, so without further ado, let’s start!


When Do You Need To Flush The Heater Core?

You have to flush the heater core when the heater doesn’t send heated air as usual. A flush can help improve the heater performance by unclogging the heater core. You will be able to detect a significant difference in temperature rise before and after the color. 


Tools and supplies

  • A large container
  • Jack 
  • Clear hoses
  • Gloves
  • Pair of pliers/screwdriver
  • Garden hoses
  • Air compressor (optional)
  • Hose clamps (conditional)
  • Duct tape or silicone coupler
  • Antifreeze solution
  • A flush kit
  • An adaptor
  • Rags
  • Safety goggles


Steps To Drain Car Heater Core

We have made a list of easy steps below, and they will answer your question about how to flush car heater core:


Step #1. Jack the car up 

Firstly, you need to park the car in the parking. Then, wait for the car engine to cool down entirely; otherwise, the hot coolant can burn you. Furthermore, you must also ensure that you park the car on a challenging and level surface like concrete. Unlike the slippery surface of your gravel driveway, a smooth surface helps to jack up the car effectively. You can use a trolley or a scissor jack to lift up the vehicle. Adjust the jack length according to your ease, and then put the jack stands for support. 


Step #2. Access the heater hoses

Open the car hood and find the firewall generally located in the engine compartment on the passenger side. There, you will see two rubber hoses in black color. One of them is the inlet, the other is the outlet hose, and both connect to the heater core. Next, you need to disconnect the hoses but don’t forget to double-check that the engine is cool. The coolant can spill from the nozzles, so put some rags below the hoses. Then, use pliers or screwdriver to squeeze the hose clamps. Slide the clamps and free the hoses from the nozzles. 


Step #3. Connect the clear hoses

We are all ready to connect our clear tubing with the nozzles. But first, you have to attach one tube with the garden hose by using an adaptor and the flush kit. Next, connect both of the clear hoses with the hose nozzles. Apply silicone couplers or duct tape to make sure they fit tightly. Then, connect the garden hose to a spigot. Consult your car’s user manual and adjust the water pressure to between 10-15 psi. 


Step #4. Perform the flush

Turn the spigot on, let the water flow from the clear inlet tube to the heater core, and then come back out of the heater inlet hose or clear outlet tube. Ensure that all this water goes into a large container and shouldn’t spill on the floor because it contains harmful coolant. Turn the spigot off when the clear water starts flowing out of the exhaust pipe. Then, disconnect the garden hose, and now you have to pour antifreeze into the heater core.

Use the same clear hose with which the garden hose was attached and fit a funnel on its end and then run. The antifreeze solution will avoid freezing water inside and eventually damage your car heater system. Let all the answers come out of the outlet hose. 


Step #5. Refill the radiator

Lastly, you have to reconnect the heater hoses with their respective nozzles. Use a pair of new clamps if the old ones are in bad condition. You must ensure that both hoses have fit flush and tight. Now, open the radiator cap and fill it with a 50/50 mixture of coolant and water. Close the lid and the car hood, and voila! You are done. You have successfully flushed the heater core.


How To Unclog The Heater Core?

No one wants to have a clogged heater core in his/her car. You can use a compressor to unclog the heater core if the water doesn’t bring the coolant with it and the heater is still not producing heat. Connect the airline with the heater core outlet and fix it with duct tape or a coupler. Apply pressure to the system, and you are good to go. 

Any stuck object or grime will come out from the heater core inlet. A radiator cleaner works the same way and is excellent for clearing clogs. But, you need a connection of clear hoses with the heater core to perform unclog operation by using a radiator cleaner. You may also be interested to know about signs your heater core is leaking.


It’s A Wrap!

Now you know how to flush car heater core. The heater core is the core part of the car heater and requires maintenance to provide warmth and coziness to you and your dear ones. The freezing weather won’t allow anyone to go home and do some work if the car heater is malfunctioning. You may also want to read about what is PTC heater in car and how does a block heater works on a diesel.

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