R0nAi

2006 Audi a4 B7 A/C not blowing hot air although the temp gauge works fine. Coolant level seems good. The weird thing is the right side of the center dash air vent blows warm air only and the passenger side air vent but not the driver side. I was thinking maybe it could be an air bubble in coolant so I want to refill it even though it’s not minimum or under. Any suggestions in fixing the heat or do i have to clean out the heater matrix. Any DIY’s out there with pics or a video?

Edward6420

I had a 2002 1.8L that would get build up from sand in the heater core (cast metal part residue that got worse over time) What I had to do is backflush the core with a hose and CLR to remove any debris. Plenty of tech details on web as to procedure.

John535is

You can bleed the heater core. Check the heater hoses at the fire wall in the engine bay. One should have a small round circle marked on it. Undo the clamp, gently slide the heater hose part way off until the hole in the small circle is exposed. You can nip the clamp up if the hose is loose but normally not a problem. Start the engine, turn the heater controls to full hot and the fan on. When the engine warms up and the thermostat opens you should get a little fountain of warm coolant spout out the hole. When its a stead stream you have bled the heater core.

R0nAi

Thanks for the answers. All I had to do was fill up the tank with coolant and drove it for 2 days it started working fine.

equilibrium

Glad you had the issue fixed. I had this problem on an 03 Passat, and I had to flush the heater core. If you're not getting proper heat during very cold weather, it's probably the heater core that it's plugged. I would recommend doing it anyway, why not get more heat, and it's very simple. The two heater core hoses should be in the front plenum between the battery and brake booster. Clamp those hoses and unplug them, flush with CLR using a garden hose or a small pump with not too much pressure, and you should do it both ways so the grime and dirt can start flowing. I don't have the pictures but when I did it on my Passat I was amazed at the gunk, sand, and **** that came out of the heater core.

If you have problems again with your heat, shoot me a pm I'll put something together.

R0nAi

I did that today in the morning and man there’s so much heat coming in. Thanks a million. Now my only problem is the p0299. I dont know what it could be. The car literally jumps when I floor it. I’m guessing it can’t be the turbo. Hopefully it’s not a bad turbo or wastegate. What do you think it could be? I removed the battery twice to reset the CEL but came back after roughly 40-50 miles. Any ideas?

equilibrium

P0299 is an underboost CEL and it usually comes on when the diverter valve goes out. The stock DV has a rubber diaphragm that is prone to tearing, even a slight tear in the DV rubber seal inside will throw that code. If you've never replaced your diverter valve I would do it and I'm almost certain it will get rid of that code, but even if it doesn't a new DV will make the car run better and you'll get better performance. They're not to expensive at the dealership or you can find one online.

Let us know if you replace it.

R0nAi

It would be a miracle if it’s only the DV. Hopefully it’s just that and not the whole turbo or the wastegate. My car has over 120k miles so I’m fearing it might be something bigger. On the other hand since the car pulls pretty well I’m assuming and hoping it’s just the DV. I hear no turbo whistle though when I floor it.

equilibrium

I'm pretty sure it's just the DV. 120k miles is not a lot, I mean yeah it's up there but the engine has a ton of life left, especially if it's pulling. Also, you're right, if you hear no noises, or you're not burning oil, turbo should be fine.

Please update this post when you replace your DV, I really want to know if that cures it.

Good luck,

R0nAi