2 cats? Geez, might as well have just stuffed a rag in the pipe to "clean" the air. Good you got that out.

What 71Yella sez: it's running open-loop on you because the ECM thinks it's cold.

Easy fix, but there's a bit of crap to get out of the way to get at the t-stat. A/C doesn't have to be discharged-it will lift out of the way.