A3 1.9 TDi SE 2002 blowing cold air but with a normal 90c running temp

[delboy59]

Hi all I`m new to the forum so hope some one can help my daughter has just bought herself this A3 complete with this cooling system problem when up to normal running temp of 90c it runs fine but the heater is constantly blowing cold air she drove it 60 miles to college this morning and said it crept just over 90c a couple of times but went back to normal quick enough if you feel the top hose when its been running and warmed up it is very hot but bottom hose is cold I have a radiator spare that can go in it as someone said they thought it could be a blocked rad but after reading round and talking to a friend I`m thinking that it could be the stat or temp sender unit these would be easier options than taking the whole front of the car lol. There is 1 other strange problem and that is the fuel gauge goes the wrong way it shows empty when full and seems to go up when going down any help with either or both of these problems would be greatly appreciated.:1zhelp:

[NickPicks]

Do you mean blowing cold air from the air con vents?

If it's getting up to 90 degrees but not blowing hot air, then I'd suspect that the air con has a fault, or that the heater matrix is blocked / has an air lock.

If the radiator was blocked, I'd expect the engine to overheat, but the heater should still work. (actually in this weather, the engine probably wouldn't overheat)

Are you able to scan the a/c system with vagcom? there might be a flap motor failed / stuck which is stopping the hot air. You could also try bleeding any air out of the cooling system.

not sure about the fuel gauge - could someone have replaced the sender unit with the wrong one? Again, vagcom would help with a scan on the instrument panel, and output tests to make the panel move the gauge from empty to full.

[zollaf]

remove the small pipe from the top of the header tank. start the car up and you should get a good flow of water from it. if not, you need a new water pump.

[delboy59]

thanks for the quick reply`s guys i`ve
got a hand held vag reader i`ll see what that throws up when she`s back from college on Friday cheers.

[delboy59]

just a quick update talked to my daughter on phone this evening and she informs me that when sitting idling the temp drops back to 70ish dont know if this makes any difference cheers.

[kite]

just a quick update talked to my daughter on phone this evening and she informs me that when sitting idling the temp drops back to 70ish dont know if this makes any difference cheers.

Sounds like the stat has failed open.

Sent from my GT-I9305 using Tapatalk

[NickPicks]

I agree with Kite. My Passat 1.9 tdi also drops to about 70 when idling, and only reaches 80 when driving, (I just haven't got around to changing the stat yet), although I do still get heat out of the blowers.

[delboy59]

Heres an update shes back from college and informs me that on the way down it took about 30 miles but then it did start to blow hot air and on the way back got to temp and was blowing hot air all the way back in fact with the heating on full she had to open the windows (she didn't like to turn it down just in case it over heated lol ) so I took the readings and here it is Number 1. 18080 coolant fan control 1. open or short to ground P1672 , Number 2. 00532 Transmission control module relay supply voltage (B+) malfunction low battery or bad ground supply voltage (B+) supply voltage B+ , Number 3, 00668 Battery power voltage supply ( terminal 30 ) or supply voltage terminal 30. I think maybe it could be a bad battery as it was a second hand one but any more help would be greatly appreciated thanks. sorry forgot to say it only dropped back a tiny bit not to 70 when idling or going along without accelerator.

[NickPicks]

clear those codes and see if any come back, but the reason for underheating is most likely to to be a failed thermostat.

I think they're fairly easy to replace on the 1.9 - you might have to remove the alternator to get to it.

[crackpotterpig]

I agree with others definatley a thermostat, replaced mine a few months ago a bit fiddly on the 1.8tm a bit easier to do on the 1.9tdi though I think.When running properly the temp gauge should stay at about 90 when driving.

[delboy59]

She`s away for the weekend so she had a longer trip yesterday and she found that the temp only starts to creep up when she accelerates harder to overtake ( not every time though ) she thinks its when the turbo kicked in I do know for certain it has had a new turbo fitted so I should be able to rule out that and the reader didn't throw up any codes for that so hopefully you guys are right with your first ideas and the stat is either faulty or maybe stuck so just thought id let you know the the latest things she has found out in case it points to something different all together ill try get hold of a thermostat on Monday but I may have to wait until Tuesday depends whether TMS have one in stock speak later thanks.

[Cawley92]

Wondering if anyone could help me. I've recently had a new water pump and belt fitted because my a3 1.9tdi losing water. Upon replacement, it then broke down cause of a switch on the big black pipe feeding to radiator. Was replaced and also system bled (as original mechanic didn't do)

The problem I still have is that the car gets up to temp eventually running down the motorway for instance. Then upon slowing/idle the blowers start blowing cold again - in this time also, the temp gauge is up at 90 and blowing cold. Then tends to drop back to about 50/60/70.