A4 Engine Heat Issue

sprinter1801 · 13-01-2010, 03:46 AM

My A4 2.5 tdi has a problem heating up. It takes about 15 mins of hard motorway driving to get it up to the 90 deg mark. Then it's happy.

But if you turn on the heater blower with the heat setting on max the engine temp starts to drop.

Had this problem for a few months now. Cam belt was changed last week so I asked dealer to change water pump and thermostat which they did but I still have the problem. Also changed the temp sensor (green type) on the top of the engine.

Any help would be cool as the dealer says there is noting wrong but I know there is as it never used to be like this.

Thanks All

PetrolDave · 13-01-2010, 11:22 AM

Thermostat stuck open?

sprinter1801 · 13-01-2010, 06:40 PM

it's new so it should be ok but I had the problem with the old and new stat so I don't think they were both stuck open

I have been told today that it might be something to do with an electrical heater that the older 2.5tdi A4 had but don't know to much about that, Yet

sprinter1801 · 08-02-2010, 08:08 AM

Still got this problem and Audi can't sort it. They are now talking to the factory to try and sort the problem out.

They are all now thinking it might be the viscous fan coupling but want to be shore before changing it.

So we shall see in the next few days I hope

sprinter1801 · 12-02-2010, 03:44 PM

Been looking at this again while waiting for a reply from Audi.

Any 1 know what the small fan beside the larger one is used for and should it be running all the time when the heater controls are switched on

Thanks

PetrolDave · 12-02-2010, 05:11 PM

Quote:

Originally Posted by sprinter1801

Been looking at this again while waiting for a reply from Audi.

Any 1 know what the small fan beside the larger one is used for and should it be running all the time when the heater controls are switched on

The small fan is on when the air con is on to cool the air con heat exchanger which is mounted with the radiator.

sprinter1801 · 12-02-2010, 08:11 PM

Thanks for that Dave.

Should the fan run all the time the climate control panel in the car is switched on even if the setting is for full heat.

As soon as I switch the panel on the fan starts what ever the setting.

Also do you know what controls it. There is a small box just above it that looks like the control unit but don't know how to test it.

sprinter1801 · 12-02-2010, 10:48 PM

More Info !!

Had a look at wiring digram and found that the fan control is fed via 5 amp fuse f4 in fuse box and then the return goes via j248 Diesel direct injection system control unit.

So by my thinking the Diesel direct injection system control unit earth's the feed from f4 and the fan module. So if there is a fault it's going to be the Diesel direct injection system control unit.

What do you think ?

Any help would be good as it's getting a bit heavy for me.

PetrolDave · 13-02-2010, 09:50 AM

Quote:

Originally Posted by sprinter1801

So by my thinking the Diesel direct injection system control unit earth's the feed from f4 and the fan module. So if there is a fault it's going to be the Diesel direct injection system control unit.

More likely one of the sensors feeding the ECU which makes it think the engine is hot, so it turns the fan on.

Suspect sensors first, only afetr having proven them all OK suspect the ECU.

You really need to do a VAG-COM scan for fault codes...

sprinter1801 · 14-02-2010, 09:47 PM

done a vagcom scan a found 1 fault

00716 Air recirculation flap positioning motor (v113)
41-10- Blocked or No Voltage - Intermittent

Nothing else stored

changed the engine temp sensor but have been told there might be 1 in the rad out flow pipe but not shore, Can't see down there. Will look on monday

13-01-2010, 03:46 AM	#1 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	A4 Engine Heat Issue My A4 2.5 tdi has a problem heating up. It takes about 15 mins of hard motorway driving to get it up to the 90 deg mark. Then it's happy. But if you turn on the heater blower with the heat setting on max the engine temp starts to drop. Had this problem for a few months now. Cam belt was changed last week so I asked dealer to change water pump and thermostat which they did but I still have the problem. Also changed the temp sensor (green type) on the top of the engine. Any help would be cool as the dealer says there is noting wrong but I know there is as it never used to be like this. Thanks All

12-02-2010, 08:11 PM	#7 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	Thanks for that Dave. Should the fan run all the time the climate control panel in the car is switched on even if the setting is for full heat. As soon as I switch the panel on the fan starts what ever the setting. Also do you know what controls it. There is a small box just above it that looks like the control unit but don't know how to test it. Last edited by sprinter1801; 12-02-2010 at 08:13 PM.

13-01-2010, 11:22 AM	#2 (permalink)
PetrolDave Subaru Impreza WRX Join Date: Jul 2005 Location: Hampshire, U.K. Posts: 2,968	Thermostat stuck open?

13-01-2010, 06:40 PM	#3 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	it's new so it should be ok but I had the problem with the old and new stat so I don't think they were both stuck open I have been told today that it might be something to do with an electrical heater that the older 2.5tdi A4 had but don't know to much about that, Yet

08-02-2010, 08:08 AM	#4 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	Still got this problem and Audi can't sort it. They are now talking to the factory to try and sort the problem out. They are all now thinking it might be the viscous fan coupling but want to be shore before changing it. So we shall see in the next few days I hope

12-02-2010, 03:44 PM	#5 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	Been looking at this again while waiting for a reply from Audi. Any 1 know what the small fan beside the larger one is used for and should it be running all the time when the heater controls are switched on Thanks

12-02-2010, 10:48 PM	#8 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	More Info !! Had a look at wiring digram and found that the fan control is fed via 5 amp fuse f4 in fuse box and then the return goes via j248 Diesel direct injection system control unit. So by my thinking the Diesel direct injection system control unit earth's the feed from f4 and the fan module. So if there is a fault it's going to be the Diesel direct injection system control unit. What do you think ? Any help would be good as it's getting a bit heavy for me.

14-02-2010, 09:47 PM	#10 (permalink)
sprinter1801 Shank's Pony Join Date: Jan 2007 Posts: 19	done a vagcom scan a found 1 fault 00716 Air recirculation flap positioning motor (v113) 41-10- Blocked or No Voltage - Intermittent Nothing else stored changed the engine temp sensor but have been told there might be 1 in the rad out flow pipe but not shore, Can't see down there. Will look on monday