Heater not working; the air is not hot.


Asked by Dec 07, 2014 at 11:17 AM about the 2005 Hyundai Elantra GLS

Question type: Maintenance & Repair

Question about a heater.  My mom's car's heater isn't blowing hot air; it doesn't heat up.
She took it to a local mechanic who changed the thermostat, but it still doesn't work.  
Then he flushed it for her…still no hot air.  It's leaking a little fluid onto the street
sometimes, but not pouring it out.  Any ideas?  thanks!

5 Answers


It will be the blend door actuator under dash,that controls, the tempreture in the car,look it up on google,it will show you what im talking about,and as far as the leak,need to find it and repair it.

5 out of 5 people think this is helpful.

thank you T S T. We'll look into that!


Hopefully that's not your heater core leaking, it can be a pain to replace (most heater core leaks result in coolant in the passenger cabin are and not on the street though). You should find the two heater core hoses running from the engine through the firewall, they are about 1" in diameter. Put your hand near it (but don't grab it) to see if they are hot. That will tell you if there is engine coolant getting to the core. second TST is most likely correct it is a problem with the blend door or its actuator. I've read where some techs have had success getting to the blend door and heater core through the air bag opening without having to pull the dash. If you can't hear the blend door moving when shifting the temp from hot to cold in the passenger cabin, then try removing the air bag and looking at the top of the heater core where the blend door is and see if it moves. If not you might be able to swap it out the actuator through the opening. There are a lot of brittle plastic pieces in there, the actuator itself is just plastic gears in a plastic box. Check in Hyundai specific forums for tips on replacing a blend door actuator.

2 out of 2 people think this is helpful.

This problem has most likely been resolved by now, but I would like to post my thoughts for any future searchers of similar symptoms. While a faulty blend door or actuator could have been the problem, I feel that those problems are not the most common causes with the conditions as described, and as such should not be seriously considered until all simpler, more common possibilities are eliminated. As stated above, there was evidence of a small leak. I have found that even a small leak can lower the level of coolant in the system just enough so that air can be introduced into the system and create a loss of heat due to inadequate amounts of hot coolant flowing through the heater core. Coolant levels must be checked (when engine is cold) in the expansion tank, as well as the radiator, to make certain that the level is up to the neck in the radiator. My daughter's 01 Elantra was blowing cold air, while the temperature gauge registered normal engine temperature, and there was evidence of a small coolant leak. Upon checking fluid levels, the expansion tank was to the proper level, while the radiator appeared just slightly low, with the fluid level just above the fins inside the radiator. Upon topping off the anti freeze, we drove the vehicle and bled the system of air. When the engine cooled once again, we open the radiator and topped off the coolant again to the bottom of the filler neck. Hot air was now blowing from the vents without the need of spending money for needless, costly repairs. We were ultimately able to locate the small coolant leak and made the simple repair in order to prevent the loss of heat condition from recurring. Summary; a no heat condition with the engine within normal operating temperatures, usually can be narrowed down to low coolant level, air or blockage in the cooling system, faulty pressure cap, possible faulty blend door and/or actuator, or a bad heater core. Issues with a leaking heater core will generally be indicated by condensation & oily residue on interior windows, and/or wet carpet in front passenger footwell. A sweet anti freeze smell may also be apparent. A no heat condition (generally) will not be related to issues concerning the thermostat or water pump without an abnormal or inconsistent engine operating temperature reading. Hope this helps.

6 out of 6 people think this is helpful.
Brendon May

Thank you! Most helpful

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