Heater malfunctioning

I have the van listed above Touring model. I got it fixed by a Chrysler dealer because it was leaking oil. They replaced the engine oil cooler, adapter engine oil filter, the intake manifold gaskets, intake plenum gaskets, and the oil pressure sensor. They also filled it with Antifreeze and 6 quarts of 5w20 oil. The Service guy at the dealership told me that they found a code P0523 which was the oil sensor. They also cleaned the oil off of the engine and the transmission. Well I started to get a smell like burning antifreeze but it wasn't getting hot or over heating. I thought maybe they may have dripped some antifreeze on the inside when they filled it. Well now my heater doesn't come on right way when I turn it on. After awhile the heater starts blowing out heat. Then another time when I started it it did the same but this time the heat would kick in and out and then stay on like normal. I decided to turn the air conditioner on the see what it would do and the driver side blew cold air and the passenger side blew heat. I also noticed today that the fluid under the radiator cap is a brownish orange color. Could this be something they did to make this happen? What could it be? I have an appointment tomorrow so that they can check it out to see if the parts they replaced are faulty. They charge a hefty diagnostics fee if it's not their parts and ends up being something else. I don't want to be used for not knowing anything about mechanical stuff with cars and charged a lot of money.