1998 Crown Vic LX Heat/AC issue

I put a new blend door on my crown vic but the EATC is still saying it is bad when I do the diagnostic test. I have tried to reset the codes but it doesn't reset. I came across another EATC that I know works and same thing. I have heat,but it only comes out the front vents.If I put it on defrost or floor cold air comes out there and hot air out of the vents at the same time.

Car has almost 151,000 miles on it. When I bought the car,the AC worked really good but it no longer works either.

Any suggestions?

check your temperature control resistor unit under the hood near the firewall.