Heater only blowing lukewarm heat

MIKE.DEMPSEY

MEMBER
2005 HYUNDAI TUCSON
2.0L
4 CYL
2WD
AUTOMATIC
118,123 MILES

Hello. I have a heat issue any advice would be greatly appreciated. I replaced radiator with hoses. I did a x2 heater core flush. New thermostat. Replaced the blend door actuator. It has gone from no heat to Lukewarm heat. Not an air flow or fan or blowing issue as far as I can tell. Low mid high air flow changes with the dial. When it gets cold my check engine light comes on and says water coolant sensor but was tested and it in range. Any ideas as to what could help? It takes a while especially in winter to get to the sweet temperature area. Fuses are good. Could it be a relay, or this car just have no heating capabilities? Thanks

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

What you have already done is helpful. But I do have questions. First, what code do you actually get? Is it one that indicated the engine temperature is not reached within a specified time?

Next, how were the blend door actuators tested? Are you sure they are moving fully?

When you replaced hoses, how was the system bled and when flushing the core, did the water flow freely and clearly in both directions?

I need you to try something for me. First, start the engine and turn the heater on high. Allow the engine to reach operating temperature. Then, feel both heater core hoses that you replaced. Are they both hot or just warm?

Here is a link you may find of interest. It covers the most common causes of a no heat condition. Take a look through it and let me know if anything helps. Also, let me know the answers to the questions I asked.

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

Let me know what you find. Also, let me know if the system has automatic climate control or manual.

Take care and I hope you had a nice Thanksgiving,

Joe

I attached directions below for bleeding the system, the directions are for both the drain and refill procedures. Note the highlighted sections. Do not install the radiator cap until all procedures are completed and it no longer needs coolant added. You may simply have low coolant in the radiator.