Last year we had other problems(which I will make a report on) but shortly after they were fixed, the heat stopped working completely. So we searched and ordered in some part that goes on the firewall behind the glove box(can't recall the name) and had that replaced. Now the heat won't turn off, or down. It's going full blast any time the engine is running. To turn off the heat, we have to remove the glove box and disconnect the white connector in the wiring harness. During the summer, that's not a big deal- we just disconnect and leave it that way. But the other 75% of the year, it's a giant pain in the ass. If it rains, and the windows start to fog up, I have to pull over on the side of the road, get out of the drivers seat, walk around and get in the passenger foot area to reconnect the heat so I can see to drive. Ten minutes later, the rain passes, the sun comes back out, and suddenly it's a balmy 110 degrees, with humidity. So I have to pull over again and disconnect the heat. If I'm lucky, we're going in the opposite direction of the rain. If not, it's like driving a portable sauna.

When the heat is running, you can smell/taste the exhaust coming into the passenger compartment. No amount of muffler system work changes that.