I know I know.... There are tons of post on here about why our Audi's do not provide heat and how to fix it. But for those who stumble onto this thread, you are about to hear my story. It isn't bad so here it goes.

I have a 1998 A4 Quattro 2.8 that I got back in July this year. I live in Cincinnati where we just had our first snow storm (if you can consider 6 inches a storm) yesterday afternoon. I knew it would be one hell of a drive home from work with just dealing with the traffic and snow fall. But to add even more head ache to the drive, my window kept fogging up due to no heat from the defrost. I did some research and based on my findings I narrowed it down to either the thermostat, a clogged heater core, or the actuator doors. Once I found out that to replace the thermostat you have to take off the entire front end, I decided to try doing a flush. I went to a local shop and got a price to have it done thinking maybe that's the best approach. I insisted on them using the correct antifreeze for an upcharge in price. Now back in September, my radiator sprang a leak. Desperate to have it fixed on the fly, I took it to a tire place up the block from my home. I figured they added generic antifreeze and / or they didn't bleed the line. So anyways I was quoted $145 to do the flush. Since they didn't have the antifreeze there at the time, it would take 2 hrs to get, I told them to call me when it arrives. In the meantime, I went to the tire shop to ask them about the antifreeze. There was a guy there who insisted that they use an antifreeze that is compatible to all cars - even Audi!

He also said that he use to work at a foreign car place and sort of ran through potential trouble spots. Bottom line is I felt he was sincere about the antifreeze so I decided I would go back to my garage and flush out the heater core. I got some clear 1 1/4 inch hose and a bottle of CLR and some clamps at the hardware store. It was a pretty straightforward operation of removing the hoses to the inlet / outlet then putting on my hoses and adding the CLR. Let it sit for 1/2 an hour then flush with a hose. I did it twice then I put the hoses back on and started up the car to bleed the line.

So the good news is that when I turned on the heater to high, strong air was blowing out which this didn't do prior. The air was not super hot or even hot but more like a coolish / warm heat. Also the defrost mode doesn't seem to still work at all. I hear the doors closing and what not but can not feel any air blowing out the vent on my dash.

So after all that, I am wondering what I should do next. Don't suggest driving the car off the bridge into the Ohio River (my son already suggested that). Also, and heres a bummer, I removed my battery to do the job. Now my cars radio is in SAFE mode and I do not have the code. Could use some help with that too.

Thanks in advance

 

If you have access to a computer with VAG-COM, determine if there are any codes in the section for the heating and ventilating system. Sometimes the flap motors stop working or work intermittently adding to the 'no heat' issue.

Audi cooling systems MUST use coolant that meets G12 specification or you will have other issues with hose and other cooling system component failures. If the coolant is anything but a purple colour that meets the VAG specification, it should be drained as soon as possible and replaced with the correct coolant.

Bleeding the cooling system in many Audi models can require patience to get all the air out of the system. If you hear any 'gurgling' type sounds when the vehicle starts up, the system has air trapped in the heater core. I have found that following the procedure in the Bentley manual while applying pressure with a tester to the coolant reservoir speeds up the process.

 

Thanks HB for the quick reply. I was wondering if I was 'too impatient' with the bleeding process. I allowed the car to heat up (btw my temp gauge works fine and goes to the 1/2 way point - so I eliminated the thermostat being bad)and I saw a little bit of bubbles come out. How long should I let it bleed?

 

The problem with bleeding the cooling system with this design is the heater core being higher than the engine. You may want to perform the bleed procedure once the vehicle has gone through one warm up and cool down cycle to ensure there is no air trapped anywhere else in the system.

I find that applying pressure with a tester using the correct adapter for the reservoir speeds the process, but you will need to keep bleeding the system until there are no more 'bubbles' present.

 

You should pull back the left heater hose to expose the bleeder hole. Fill the system until fluid starts coming out of that hole, thats when you know the motor is filled. Start the car and make sure the air is out before closing the bleeder hole. Resume filling the reservoir.

 

Hey guys! Just wanted to come back here and fill you in with the rest of my story. Its now 6pm Sunday and I spent a good time working on the A4 Quattro this weekend.

So the big problem I was having was a lack of heat. Turns out that having air in the coolant lines can be very detrimental to producing any heat. I had none at first then after flushing out the heater core and bleeding the line I started to get air flow. But it was only luke warm air.

On Sunday, I was ready to do a more vigorous bleeding on the line. But when I started up the car early morning, the engine light was now on. I needed to go down several streets to get my son from a sleep over so during the drive the car was hesitant and stuttering (kinda like me w/ my old age ha haaa ahhh). I went to AutoZone and had the engine code read. Apparently my #3 and #6 spark plug was fouled. I purchased all 6 sparks and replaced them.

Car runs better than ever <had car since July> plus I bled the coolant line. I unscrewed the antifreeze reservoir and propped it up as high as possible. Got the car hot and saw gurgling bubbles coming from the bleed hole. I then bent the hose slightly and a good gush of antifreeze squirted out of the hole almost like squid shooting ink.

Also found the radio code in my trunk tire compartment to allow me to reset it. So after several hours over the weekend I got new sparks, heat and radio back on. Its improvement from before so worth the hassle. Total cost -- 6 spark plug @ $20 + CLR and hose for flush @ $10.

 

HB, I don't think that is quite true. Your '96 came with G11, but with a complete and thorough flush, could use G12, or standard green Prestone for that matter. Just last night I changed my '96's coolant, from G11 to G13, and even though the G13 is backwards compatible, I ran a warm-up/cool-down and drain cycle with plain water in between.

I also have no trouble purging air, it is all about technique: I pull the heater's return hose to the vent-hole position, open the bleeder screw behind the driver's side bank (one bleeder on a 12V), then with the reservoir supported as high as the hoses allow, start filling. When coolant comes out of the bleeder screw, I close that. When there is a constant stream of coolant at the heater hose, that gets put back. Next I drive until normal temp is reached, then shut off and allow to cool for safety. When not hot enough to burn you, lift the tank again, pull the heater hose to vent out the air which will have collected there. After another constant stream of coolant appears, push the hose back and clamp, then re-attach the coolant reservoir. Check and top up if necessary.

Note that at no time is the engine running while purging air, as this is counter-productive. The heater's return hose leads to the impeller, so if running, the pressure is low and draws air in.

 

Great advice turbo; I'll be sure to use your technique the next time I open my cooling system. Dealing with air in the 12v can be a real pita!

 

Just want to add one note on heater (and A/C) air output. Check the cabin air filter. I've seen them plugged tight (on various makes of cars) so there's very little air flow when set on outside air. Sounds obvious but you'd be surprised ho often it's missed on a diagnosis. I know, not the problem you were having.

 

Turbo, thank you for pointing out the differences in VAG coolant specifications, which people working at a parts retailer may or may not be aware of. The subject has also caused confusion with enthusiasts as well!

Now that you mention it, I have used Pentosin coolant in my 1996 A4 12valve. Pentosin meets VAG specification G012, but just to be sure, I went and looked at the coolant reservoir and it has 'G12' stamped on it.

I have also used Ravenol that meets VAG specification G012 Plus along with the coolant specifications of several other European manufacturers.