Interior heating takes ages to warm up

[Stickystuff]

Hi all,

So i ve had my A4TQS for around 3 months and its worked brilliantly considering what i paid for it.
Its a 2001 with 134K on the clock. IT had its cambelt and I beleive water pump done in july last year, but only around 7K ago.

Its come to that time of year where I want to 'Pre-Heat' my car in the mornings be fore i take my little girl to nursery and go to work, But the Damn thing takes ages to heat up. It will get upto 90 on the guage within 5-10 mins but the heating still takes a further 15-20 mins to come through, weather the A/C is on or off. this is with driving the vehicle. I cant get it to heat sat still no matter what. Also I noticed that when it doesn warm up sat in traffic It cools down until I start driving or I rev it slightly.

Now my first thing I plan on changing is the thermostat as it has a little dribble down it anyway. But As the car has dual zone auto climate control, I wanted to just check and see if there is anyone on here who could tell my weather there is a common fault with the units?

It all seams to work correctly and when I first got it the A/C cooled the car just how I wanted it. But since it got cold ive only noticed the ages for heating inside up! It makes no difference if i have the temp set to high or 22-23. By the time I get 'HOT' im almost at nursery, a 30 min journey from my home.

Any one can shed some light I would really appreciate!

 

[S4_dan]

Change the 'stat and whilst your at it, back flush the heater matrix to clear out any rubbish. Refill the full system with G13+ coolant and correct water ratio.

 

[pauldazzle]

+1 Stuck stat.

 

[Stickystuff]

I guess that was what I was going to try anyway! Thanks I will and a good point about flushing the matrix through!

 

[AlexGSi2000]

Ok, so the car takes around 5 minutes to get to 90 on the gauge - that I would say was fairly normal.
Once its at 90, does the temperature drop when moving or stay at 90 regardless? - if it stays at 90 then it probably rules out a stuck thermostat.

The cooling system is designed so the heater matrix will get heat first as the engine warms up - so if your temp gauge is at 90 then you should be getting hot air through the cabin.
This points me to an issue behind the engine, either an air-lock in the heater matrix coolant loop or one of the flap motors behind the dash.

First thing I would check would be to ensure there are no airlocks to the heater matrix, this is done by;

1. Removing the plastic trim covering the battery and brake fluid resovoir.etc
2. To the left of the battery, you should see two coolant pipes - this is the feed and return for the matrix
3. You will notice a tiny hole on one of the pipes close to the retaining clips - this is for releasing air-locks to the matrix.
4. Loosen the clip for this hose and run it down the pipe - so the pipe can be removed.
5. Start the engine from cold - set the heaters to blow HOT inside the car.
6. Once the engine is lukewarm - slowly slide the heater matrix pipe with the hole as-if you are trying to remove it (dont pull it off all the way)
7. if no water escapes from the hole, allow the engine to run a little longer - wait until coolant starts leaking from the small hole.
8. Slide the pipe back on and attach the clip.

If the problem is still there, then take a look at the flap motors (this will show up in VCDS if there are any issues);
Pictures on this thread; http://www.audi-sport.net/xf/threads/heater-flap-motors-where-to-buy.133234/

 

[BakPak]

Good shout on bleeding the heater matrix. My engine warms up pretty quick and sits at 90 all day long but with the OAT at 3 - 4 degrees the warm air is well not very warm at all really so I'll definitely check if the matrix has an airlock.

 

[Stickystuff]

No the temp stays at 90 no matter what situation. Once it gets there it stays there.

When I get the chance I will try that however at the end of the day today I managed to get the car up on the ramp and found this.

I knew about the leak (and the oil leak) a little while back, but it's got worse since I last looked.
So I'm going to have to change the thermostat in any case.
I'll plug the car in, I haven't got VCDS but I've got a Bosch, Delphi and a snap on reader to use so I'll plug it in and see if any fault codes come up.

I have to say though I've not noticed or heard the stepper motor moving for the heat.
But I here a change in noise when I change from fresh air to re-circ, or changing from feet to air vents or to windscreen etc.

 

[S4_dan]

With a leak like that then you're probably going to be having an air lock in the system. Do the stat, and back flush the matrix and flush rest of the system. Fill with G13+ & water and run the car until it gets warms. Carefully remove the clip on the top heater matrix hose and GENTLY pull it back but NOT off. There is a little white line and in the middle of that line (on the rubber hose near the end) is a little hole for bleeding the system. Wait until all the air is out and then slide back on and refit the circlip.