A month ago I had a new thermostat put in my 2006 Stratus, and since then I can hear gurgling noises from the engine after turning it off. Today when I turned on the defroster, it blew cold air. I switched it to the floor vent and it blew warm, so I thought it just needed to warm up longer, but when I switched it back to the defroster, it blew cold again. Now all vents blow cold, even the floor vent. The heater blew warm air last week, on more than 1 occassion. Can these two problems be related and what can be the cause?

Update: I had topped off my coolant level about two months ago and checked the level today. No fluid was found in the fill container. This accounts for no heat and the gurgling noise. I haven't seen any fluid on my driveway and none on the engine. Where could the fluid have gone? It seems like too much to have just evaporated. Any thoughts?

 

my first thought is that the Thermostat housing has got a small leak in it and leaks under pressure, or that the bolts tightening down the said housing are too tight causing the o-ring gasket to leak, or the over flow container has a crack in it and is leaking there.
But the good news is if you arent overheating that most likely rules out the head gasket.

 

Why did you replaced the thermostat? Did it overheat? If not, usually the problem is that the system was not properly bled and you have air trapped in it.
This forms an air bubble which in turn allows steam to form and gurgles after you turn engine off.

 

defroster is not hot because there is no water on the heater core. Just air.