Here's the problem — Toyota builds the climate control functions for the 2005-up Avalon into the factory radio. Take out the radio, and the heating and air conditioning controls won't work.
The Metra 70-8215 harness provides a solution — remove the factory stereo from the dash, mount it in an out-of-the-way place, then connect it to the climate controls with this vehicle-specific harness. You get a new stereo and your climate controls will still work. Warranty: 30 days.
Note: This harness is for Toyota Avalon models without the premium JBL sound system. Please enter your vehicle information or call a Sales Advisor at 1-888-955-6000 to find out if this model is compatible with your vehicle.