Heater blowing out cold air

Welcome to 2CarPros.

It sounds like they want to replace the heater core. Here is what I need you to do: Allow the engine to warm up to operating temperature. Turn the heat on high. Locate the heater core hoses that will run to the firewall under the hood. Both hoses should be hot. If only one is hot, then the core may be plugged. If both are hot, then I suspect a blend air door actuator has failed. The actuator is what controls the temperature entering the interior of the vehicle.

Now, the problem I'm having is that in the US, the i-30 isn't offered. However, I believe it is the same vehicle as our Elantra. So, I attached a picture below that shows where the heater core hoses attach at the firewall. I highlighted the hose connection points.

Do this test and let me know what you find. Also, here is a link you may find helpful.

Take care,

Joe

Hi Joe,
first thanks for your reply. i have drive car and then turn on heating both hoses got hot.
i add the photo to show the hoses i checked.

Hi,
i checked again and followed your instruction.
i have noticed one hose is hot while other is not so. heat core may be blocked so what solution you recommend now?
Thanks very much.

Welcome back:

At this point, we have two choices. First, and most expensive, replace the heater core. Second, try to back flush the heater core. Basically, coolant is lowered in the radiator to a level below the heater hoses. Then, the hoses are removed. Using something like a garden hose, you will spray water through one of the hoses through the core so the water comes out the other side. Then reverse it. Apply water pressure on the opposite hose.

If you can get the water to flow easily, it should work fine. Be prepared for dirt and corrosion to come out.

Also, here is a link you may find interesting to look through. It discusses the most common causes of a no heat condition:

https://www.2carpros.com/articles/car-heater-not-working

Let me know if I can help.

Take care,
Joe

Hi,
Thanks again for your time.
i did heater core flush initially water didn't flush out but slowly once all the dirt come out flow was okay.
i turn on heat on full and noticed the same issue one hose was warm other was cold after starting car about 10 minutes.
so is it heater core issue and have to replace it?
Thanks

Welcome back:

If it was plugged, you may have to do it again. Did you reverse flush it? As I mentioned, I don't have the specifics on this vehicle. It could have a heater control valve which stops the coolant supply to the heater core until heat is demanded. However, chances are it doesn't. Also, did you bleed the heater core? What I do on some vehicles is the line that is cold, I loosen the hose clamp and slightly remove the hose so air can escape.

Let me know if that helps.

Joe

Hi Joe,

After doing flush again the heat core i got some heat to the system but not as i have seen my other give out. heat is mild heat i got, but today when i drove car today it is very little heat i go.t i upload video you can see i flushed and got water flowing and clean.

Were you able to back flush it too? It sounds like the heater core is where the issue is if you are getting a little heat now. If you can, upload the video so I can see what is happening. Do me another favor. The i30 isn't offered in the US, so I have very limited technical information. However, the systems work primarily the same on all vehicles. Can you tell me if both of the heater hoses are not getting hot? Can you notice any changes in their temperatures?

Take care,
Joe

Hi,
i have noticed that one hose is more hot than the other one?

Welcome back:

That is normal because the heater core gives the coolant a place to cool off. But that shouldn't be a big variation in temperature. The supply line will be the same temperature as the coolant in the engine. The return line will be slightly cooler. Did you flush it in both directions? (Back flush)?

Let me know.

Joe

Hi,
yes i give flush both ways though i try to keep water pressure normal not fast like jet wash.
i flush system both sides through both hoses.
Thanks

Happy to help. Let me know if you have other questions.

Take care,
Joe

Hi,
Problem stays on even after flushing my heat core. it gives very little heat after that.
so what next step would be i should try?
Thanks

Welcome back:

If the heater hoses are hot, then chances are you have a blend air door in this vehicle. As I mentioned, I don't have the specifics on this model. Check to see if there is what is called a blend air door. That is what is responsible for the air temperature entering the vehicle.

Here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/replace-blend-door-motor

Let me know what you find.

Joe