No Heat Change thermostat on hyundia elantra and still no heat, cool air stills blows after the car is running at normal tempature.

Hi, Yes you have an air lock in your system, you may get this sorted by 1/. Removing one of the cooling hoses & try to blow with air.
2/. Drain all the system then put your heater on inside the vehicle & have the engine running & refill the system Start to do this from a cold engine. Please leave me feed back: Malcolm Campbell, Thanks.

The thermostat "seals" the cool coolant giving up (rejecting) heat in the radiator & heater core from the hot coolant absorbing heat in the running engine "block".

When the coolant in the engine reaches a specific temperature (180 ~ 195 degrees) as determined by the value selected by manufacturer or when replaced, it opens and allows the hot coolant in the engine block to be pumped out to the radiatot & heater core for cooling and the cool coolant in the radiator / heater core is pumped into the engine block - replacing the hot coolant. The thermostat senses cool coolant in the engine block and seals shut until the temperature of the coolant in the engine block rises to 180 ~ 195 degrees again. This process continues over and over for as long as needed.

You should check to make sure that the coolant level in the reservoir / radiator is sufficient by checking when cold. Do NOT remove a radiator cap when it is hot! With the cap off, start the engine and add additional coolant as the engine warms up to normal operating temperature. If coolant levels are ok, the trouble could be related to the thermostat or possibly a faulty temperature sending switch. This means that the temperature of the coolant is fine - but the switch or sensor that converts the temperature to a voltage for the gauge on yur dashboard is the problem.

If the temperature is fluctuating up and down, you should have it fixed. Good luck!

Change the thermostat and make sure to bleed the system of air when refilling with coolant.You should have lots of heat in a 2005 Elantra at idle or driving.

try feeling your heater hoses going from the engine to the heater core. they should be hot at operating temperature. If one is hotter than the other noticably it would indicate a restriction in the core most likely. A partially stuck thermostat could also cause loss of heat but you say the temp is normal. Start with checking hose temperature if they are both on the cool side compared to the radiator hose then further diagnostics are necessary. hope this helps. Keep in touch.

try a piece of cardboard in front of the radiator to reduce the air flow and chill factor through the radiator and around the engine

Check the sensor which controls the cooling fans that cools the radiator it prevents the engine from over heating and allows the temp gauge to stay at normal range.recently had problems with my 2003 impala overheating it was the sensor had the thermostat replace as well.

with winter being here you might want to consider having a new thermostat put in to increase the heat in side,but make sure your radiator is full when engine is cold

check your coolant level if it is low top it off. if it is full you may need to change your thermostat to get the temp back to normal. for the heat check the heater control valve to make sure it isn't stuck (heater control valve should be located against fire wall connected to heater hose.

Sounds like the thermostat is trying to stick,and is causing the engine to over heat,therefore condenser is not cooling the freon down enough to cool.Have the thermostat changed and the cooling system bled out,this is most likely the cause.

Just finished fixing my daughters 1999 taurus heat. It would blow warm only when running down the road. At idle it blew cold. I started with replacing thermostat, and water pump because they are the easier fix. Still did not help. Then I replaced the heater core. A daunting job but not that hard to move the dash slighly out of the way to replace. There is a good write up at tarusclub.com. After that, heat was better but at idle, it would still blow cool sometimes. Researched and found answer. Park car on the steepest hill you can find with front of car up. Start car and take off reservoir cap. Let car warm up and keep rpms about 1500. After a while the fluid will come running out of the car and all over the place but it will bring air bubbles with it. Reduce rpm, add more fluid and repeat about 3 times. It will make a mess but after that, the heater works perfectly. We get heat long before the temp gage indicates any and it never blows cold unless you lower the temp.