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Heater problems

Tiny
MRCHIRPY
  • MEMBER
  • 2008 HYUNDAI ELANTRA
  • 0.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
Hot air coming through vents on driver's side dash and floor. Passenger side has light air from dash and cool air from floor vent. Blend activator seems to be working. What else could it be? Do I have to replace entire distribution box?
Saturday, January 13th, 2018 AT 7:54 AM

22 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Blend doors working is not an indication that all are good. They must be aligned and move to specific position as designed for system to function correctly. This guide can help us fix it

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

You need to check if any part is out of alignment or dislodged. could be a worn linkage. If the blend motor is working but not getting to correct position, it could be weak or worn and has to be replaced.
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Sunday, January 14th, 2018 AT 10:10 PM
Tiny
THERESA HUGES
  • MEMBER
  • 1 POST
  • 2007 HYUNDAI ELANTRA
  • 75,000 MILES
My heater blows normal on the driver side and blows cold air on the passenger side also when temp is below minus 20 both sides blow cold air. Do you know if this is a common problem. I have checked my collant level and it is fine
Theresa
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Friday, February 12th, 2021 AT 11:11 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You have a door issue here-could be a vacuum/actuator/HVAC control module-it This guide can help us fix it

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

Please run down this guide and report back.
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Friday, February 12th, 2021 AT 11:11 AM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Just to add my 2 cents on this one. Normally when you have no heat after doing anything to the cooling system it is because you have an air pocket as mentioned prior in the heater core. The best way that I have found to get rid of an air pocket is to use the funnel that you will see attached. This will help eliminate air pockets and I would fill the radiator so that this funnel is a quarter of the way full and then when the thermostat opens, it will pull the coolant in funnel in rather then air. Then you will need to be ready to keep filling it so that it doesn't empty and this will prevent the system from pulling in air. Then you will want to just let the vehicle idle for about 15 minutes with the funnel about a quarter of the way filled and you will see the air pockets working out through the funnel.

Let us know if you still have questions. Thanks
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Friday, February 12th, 2021 AT 11:11 AM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2006 HYUNDAI ELANTRA
  • 165,000 MILES
My heater does not blow hot when the fan is turned on. If it is off I can feel the heat from the vent but it will not blow hot. I just had a new Radiator, hoses and a new thermostat put in and it still is not working correctly. Could it be possible that the door that normally opens when I have it set to cold is not shutting? It is very cold and I am at my wits end. Please help
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Friday, February 12th, 2021 AT 11:12 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I believe you are referring to the blend air door, and yes that can be what is causing the problem for you. If it doesn't function properly, you won't get heat. Also, make sure that both heater core hoses are getting hot. If they are, then the core is working. If only one is hot, chances are the core is plugged, One last thought. Even though you replaced the thermostat, make sure the engine is warming up to operating temp.
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Friday, February 12th, 2021 AT 11:12 AM (Merged)
Tiny
YAHRI
  • MEMBER
  • 1 POST
  • 2005 HYUNDAI ELANTRA
  • 3 CYL
  • AUTOMATIC
  • 120,000 MILES
Was driving home from work and notice the heat not working. Then as I was going up a hill the car stalled then shut off. Got it back started and was trying to get home and it overheats (starts smoking too) soon as I hit the highway. Tried to start the car and now it’s not turning over. Radiator cap is damaged and I put water in it since I didn’t have coolant with me and when I tried starting the car some came back up.( I do not know if that’s normal)
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Friday, February 12th, 2021 AT 11:12 AM (Merged)
Tiny
STEVE W.
  • MECHANIC
  • 13,577 POSTS
From the description it sounds like the coolant ran low and you baked the engine. At this point you need to determine a couple things, one is where did the coolant in the system go and second did the overheating cause other failures. If there are no signs of coolant leaking then it could be that you already had a bad head gasket and the coolant was being burned inside the engine. To see what is going on, you can try a couple things. These guides and video can show you the testing required to see where the coolant is going and should give an idea of what the issue is:
https://www.2carpros.com/articles/head-gasket-blown-test
https://www.2carpros.com/articles/radiator-pressure-test
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Friday, February 12th, 2021 AT 11:12 AM (Merged)
Tiny
CHRISNXC
  • MEMBER
  • 2 POSTS
  • 2003 HYUNDAI ELANTRA
  • AUTOMATIC
  • 99,600 MILES
I was driving Friday night and on the way home my car started to steam, so I pulled over and opened the hood and coolant spewed everywhere, I put coolant in and there was a leak somewhere, but I needed to get home, so I put the coolant in, filled the reservoir, and drove home. It seemed to work, the just as I was getting home, the heater started blowing cold air, and the temperature gauge went up again. I drove to advance auto the next day to get a new thermostat and gaskets, and called my friend, who's a mechanic to see she I could get them replaced. The car has been blowing cold since, and the bottom hose remains cold while top gets hot. Is it the thermostat? What else could it be?
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Were you able to actually fix the cause of the leak?
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
CHRISNXC
  • MEMBER
  • 2 POSTS
There's still a leak. It drips at the bottom. I had the radiator replaced 3 years ago, haven't had a problem since.
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
You do not have heat because the heater core is empty with coolant. You MUST fix the leak in order to correct your heat issue.
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
MOONUNIT
  • MEMBER
  • 1 POST
Just above/adjacent to the thermostat housing, you will find a brass plug three prong sensor that is seated in block. This sensor, if bad will shut down the whole cooling system. FYI-Do not replace with generic part-it will not last. Removing the sensor wiring clip is tough. Chances are you will crack the plastic coupling and it goes down hill from there. This is part of the wiring harness and cannot be replaced. The release catch for the coupling is underneath and impossible to get at. First remove the heat cover protecting the wiring, then attempt to release the clip. After that its a piece of cake. Unscrew the sensor, put a new one in. Sensor is not cheap. Get is from Hyundai parts. Good Luck
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
SBUDWICK
  • MEMBER
  • 1 POST
  • 2003 HYUNDAI ELANTRA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
Replaced thermostat, worked good for one day.
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
If you have poor heat at an idle and good heat when the engine revs, chances are you are low on coolant. Check that first and let me know what you find.

Joe
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
JKSM MCCUEN
  • MEMBER
  • 1 POST
  • 2002 HYUNDAI ELANTRA
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 88,500 MILES
I have a 2002 Hyundai Elantra and my heater does not work. The AC works fine. I have none of the main symptoms of a heater core problem. So what could be the problem? Thanks KLM.
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both too hot to hold. If they are.

The heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
Check the thermostat or change it. And bleed the system
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Friday, February 12th, 2021 AT 11:13 AM (Merged)
Tiny
THOMAS FIELDS
  • MEMBER
  • 1 POST
  • 2002 HYUNDAI ELANTRA
  • 2.0L
  • 4 CYL
  • 256,000 MILES
Fan works cold air coming through vents. Air blow to floor and vents correctly by selection.
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Friday, February 12th, 2021 AT 11:14 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi and thanks for using 2carpros.com

Only a few things can cause no heat, low coolant, a plugged heater core, damaged blend air door actuator, or heater control valve. First, take a look through this link. It describes the most common causes for no heat.

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

Let me know if the link helps or if you have other questions. I attached a picture of the actuator I mentioned. It is responsible for allowing heat or AC into the vehicle. It is located under the dash on the HVAC unit. See pic.

In all honesty, if the coolant is full, and both heater core hoses are hot, this is my first suspect.

Take care.

Joe
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Friday, February 12th, 2021 AT 11:14 AM (Merged)

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