2003 Buick Renezvous heater blows out cold air?

2003 buick Renezvous. If it has the 3.4l 3400v6 I can almost guarentee you it's the heater core. I had a 2001 Pontiac Grand am with the 3.4l it had 24,000 miles on it and it needed a heater core because I was getting ice cold air when the heat was on. Warning be sure to get the radiator flushed when replacing the heater core. Also make sure they use dex cool. Hope this helps!

How many miles do you have on rendezvous? Between 60 and 80,000 the intake gasket will go out. Dex-cool in your vehicle is a major problem. It gums up more vehicles than anything I know.

8) start by making sure that the radiator is full, if it is. The thermostat would be the cheapest and easiest thing to try,
:wink: I agree that the intake gaskets are common to leak on these engines also.