cypher101

I just bought a 2004 a4 1.8t quattro from a private seller. The car is in very nice condition. But the heat dosent work. I do not believe the heater core is blow, because I dont smell any coolent and am not loosing any coolent. Any sugestions? Also I noticed the rear defrost wont work either. Any help would be great. Thanks I need to fix these problems ASAP!

cypher101

Blown*

BISHILVR

The two problems are likely not related, the rear defroster is electric only, check for a blown fuse, a bad switch or a broken grid on the back window, turn on the defroster and check for 12v across the two terminals on the back window and that will eliminate the fuse or switch being bad. The heater problem is a common one with the B6 and the 1.8 option unfortunately, but there are alot of threads on here about it if you search, it comes up weekly pretty much. Some common culprits are an air pocket in the cooling system (for alot of different reasons) or a failing thermostat or a clogged heater core.

John535is

agree, have you bled the coolant to confirm you don't have air in the coolant?
Seems more common with this model than others that an air pocket can bet trapped in the heater core.
Start with that, bleed it once, run the engine with the heater on, bleed again, repeat 3 or 4 times. You need it to be hot so the thermostat is open and all the coolant is flowing in the system.
Then check if the hoses (both) going into the grommet in the fire wall are actually getting hot. That will start to isolate if you have a problem on the engine side (thermostat or blockage somewhere) or if it's the heater core or valve.

lyleswk

Clogged heater core is also very common. It has very small passages that clog easily if coolant is not replaced fairly often.

cypher101

thanks guys. i believe it is a clogged heater core