Newbie help please. Coolant and heater blower issue

[macjamA3]

New to the forum and new to Audi and require some help. 

Car reaches temp fine after approx 2-3 mile (90 degrees) and sits there firm. 

Heater blows cold all the time. Temp gauge shoots up to the red, alarm bells go off saying check coolant level and switch off engine. 

Switch it off, turn it back on temp reads 90 degrees again, warning goes off, no loss of coolant at all. 

Only had the car a week and it's already doing my head in (new heater motor/resistor, new ignition barrel, radio switches itself on and off, central locking playing up on key) 

So a nice simple fix would be good before I decide it goes back to the dealer permanently.

[Stevey Y]

2 hours ago, macjamA3 said:

New to the forum and new to Audi and require some help. 

Car reaches temp fine after approx 2-3 mile (90 degrees) and sits there firm. 

Heater blows cold all the time. Temp gauge shoots up to the red, alarm bells go off saying check coolant level and switch off engine. 

Switch it off, turn it back on temp reads 90 degrees again, warning goes off, no loss of coolant at all. 

Only had the car a week and it's already doing my head in (new heater motor/resistor, new ignition barrel, radio switches itself on and off, central locking playing up on key) 

So a nice simple fix would be good before I decide it goes back to the dealer permanently.

Hi the heater matrix is possibly blocked or the thermostat is faulty [temp sensor] on the thermostat, I would be taking it back, I hope you didn't pay for all the other parts.

Steve.

[cliffcoggin]

23 hours ago, macjamA3 said:

Only had the car a week and it's already doing my head in (new heater motor/resistor, new ignition barrel, radio switches itself on and off, central locking playing up on key) 

Take it back to the dealer. It may be a simple fix or it may be an expensive one. Either way you should not have to bear the cost.

[saffa]

Hi,did you sort your issue. I have the same problem eith my car

[cliffcoggin]

Marcos.

What was the outcome of your problem? Other forum members have taken the time to offer suggestions, it is polite to make the effort to respond to them.

[macjamA3]

Hi

I sent it back to the dealer I purchased the car from, he replaced the thermostat, cam belt and water pump, heater matrix and it still does it randomly. I suspect its an electrical issue as within seconds the temperature gauge returns to normal temp 

[cliffcoggin]

Thanks for your response Marcos, which may well help others with a similar problem.

[SkeeF PRO]

  Hi everyone. Please help 🙏

  I’ve got similar issue. For about a year fighting with the problem…
I get my next one Audi A3 about a year ago. Actually there was an idea to learn about fixing the cars in practice) due to garages becoming more and over expensive. So at the moment most is sorted in my car. The only problem stays - heater.
  As I find out the coolant doesn’t run into the Heater Matrix. I have changed thermostat two times (last time the most expensive top grade), new heater matrix installed, new water pump and camber, no leaks, no sweet smells from exhaust, oil in place and good condition. I even have done EGR bypass. Just in case of potential blockage there. Flange checked. 
  Time to time the coolant comes into the system in two cases. On high RPM (over 3000) or Start - Drive 10-15 minutes - Stop and switch off engine for another 10-15 minutes, repeat 5-6 times… Also if I’m driving long distances like motorway for 1-2h the dashboard signals low level of coolant. Ok… I’m very carefully opening the lid of expansion tank to top up the liquid but coolant comes from somewhere in the system back to the tank to the max level! Anyway heater was working about 1 time of 20-30 drives. 
  One of the mechanics ask to check how it will be if I’ll bent a pipe what is going to the radiator. And it makes sense!! Finally! ))) I squeezed the pipe probably enough to reduce the flow in there for 80-90 percent. Heater now works 1 time of 4-6 drives. But still not every time. 
  Maybe in my case additional auxiliary water pump like for parking heater could help to sort it out? Or there could be something else for proper solution? Any ideas?

Thanks 🙏 

[cliffcoggin]

Chances are you have an airlock which can be difficult to eliminate. If you can apply vacuum to the reservoir and get lots of air bubbling up from the system that would be confirmation. Top up the reservoir and repeat until all air is out.

[SkeeF PRO]

As I know in this Audi the air automatically supposed to go out of the system while running. But still believe that good idea to check with vacuum. Actually… Is it possible that air blockage could cause extra pressure in the cooling system? Is the cap on water tank shouldn’t release that extra pressure? 🤔

Edited November 29 by SkeeF PRO

[cliffcoggin]

What can happen if there is air in the system and the pump does not make enough pressure to move it, is that the air expands as it heats up which pushes coolant to the reservoir and out of the overflow. That coolant is lost, so when the car cools down even more air is drawn into the system. You need to get rid of the air before the cycle of heating and cooling begins.

It is a problem that only affects a few models as it depends entirely on the design of the cooling system.

It's comparable to air in the central heating system of ones house. Air will collect in the tops of the radiators, particularly those on the upper floors, and sometimes can not be moved by the pump, hence the need to bleed the air at each radiator to restore flow.