HVAC - What did I break?
 

So, my '90 Camry has this annoying issue with the HVAC cold/warm blend door. If you have it on full hot, and turn it down a little then back up, it won't go all the way "hot." You have to pull it all the way to cold then back to hot to get it to close off the "cold" side completely. This happened yesterday when I started it to let it warm up while I finished getting ready. When I pushed it to cold and back to warm, I heard something break off and fall into the bottom of the box. I was a little over zealous with cold, 24 year old plastic. I know. Stupid. This was pre-coffee, outside in 15* weather in my pajama pants, a hoodie, and water shoes. My brain had not yet switched into "careful logic" mode. I was still in "FUDGE NUGGETS IT'S FREAKIN COLD LETS GET BACK IN THE HOUSE NOW" mode.

I haven't touched the lever since because I am afraid that if it moves the blend door, it will break completely in a not-warm position, negating the purpose of a winter car.

I do want to fix this of course, but I'm not sure what I broke. I am just wondering if someone else has had the box apart and knows what's in there. I assume I broke either the blend door hinge, the point where the cable attaches, or possibly the blend door it's self.

Is this HVAC automatic temp controlled, if not there may not be a blend door?

On a manual systems the temp control adjusts coolant flow to the heater core.

What HVAC control do you have? Is this a slide lever and not a rotating knob. If lever, make it is not for inside or outside air selection.

Mine is the lever type. Are you sure on the '90 having the coolant flow based temp control? It really feels, sounds, & acts like a door... You can even here the "PONK" sound of it closing when you go from one extreme to the other. It was when it hit this extreme that I heard something break.

I'm going to tear it apart this weekend, I think. It's been a rough couple days at work and I'm way, WAY behind so I may have to work the weekend.

May have both. Check under hood for coolant flow valve.

The mix door has an arm off the hinge rod, the cable moves the arm which moves the door. If door appears to make noise when it shifts position perhaps something else broke off like the cable sheath retainer.