My Sonata is equipped with the DATC; dual zone automatic climate control. For quite some time when my car was newer the system worked perfectly. Unfortunately I can no longer say the same.

The system can no longer maintain a constant temperature. The cooling on the driver side vents is lethargic and mediocre at best in comparison to the actual cold air coming out of the passenger side vents. I find myself always leaving the temperature on low, even at night when the temperature is dropped, which is bizarre. When the car was newer I could set the temperature to low, 63 or 64 degrees, even on a hot sunny day and within being less than 2 miles away from my house the cabin would be ice cold along with goose bumps on my arm's. Now I find myself remaining on the temperature setting of LO to receive adequate cooling. Even on a hot sunny day with both sides synced to the LO temperature setting, I find that the driver side isn't cool and comfortable enough with frosty ice forming on the front passenger side window while outside temperature was in the low 90s. Many times I have heard and felt the full activation of the heater while A/C was set to 68 or 70 degrees.

I just took my car into the Hyundai dealer yesterday. They kept my car for the entire day and told me that everything was working properly with the HVAC system. In conversation he did admit that my temperatures were off half a degree and they have received other complaints from people having to maintain lower than normal temperature settings. I strongly believe that something is wrong here...