I'm pretty mechanically inclined but I'm not sure if I'd want to tackle a tb replacement. As far as damaging the engine, I have not seen the temp go past the half way mark without the ac on, even after an hour of driving. Could a bad thermostat(or partially clogged like mine may be) cause the car to overheat without the AC on??

 

Ok, I didn't read something correctly earlier. I missed it only happens when the AC is on. Sorry. Ignore most of what I have told you already.

The AC fan has 2 speeds, high and low, it's very possible that your fan is not engaging the high speed when it should. I have the 2.8 so my engine only has 2 total fans so I am not as familiar with the 2.7's 3 fan layout.

Off the top of my head I am not sure how to test the high/low fan speed. Is the car overheating on the HWY with the AC on?

 

I dont own a laptop. But I did notice today after a 15 min drive that the op temp was normal when I shut the car off outside the store I was at. Then when I started it back up, it was a little above normal then after about a min it dropped back to normal again. Also, when I was at the dealer lsat year for an alignment, they scanned my car and said I had a faulty temp sensor.

 

Just read your post about missing the part about it only happ w the ac on..LOL, I guess i'm kind of releived?? Come to think of it, it didnt overheat w the ac on while driving on the highway...

 

I feel bad for skipping over that part and jumping to the thermostat. Maybe it's because I am dead tired and it's 1am, or more likely, I just had my thermostat crap out and it's fresh in my mind. Either way, if you're fine temp wise on the hwy with the ac on, it's doubtful your thermostat is bad, or your radiator. I'd say your engine fan (electric) is not engaging the high speed. Or maybe your mechanical fan is not engaging fully, a combo of both. If your temp sensor is in fact bad, it might not be telling the electric fan to engage the high speed.

Have any friends that might loan you their laptop?

 

wait, I'm sorry, scratch that...Well, maybe not...The first time it overheated, I was driving on the hwy with the ac on, but It didnt get hot until the hose to or from the oil cooler went and I lost most of my coolant. But today, after I had the hose replaced, I was test driving it for a while with the AC on and it started to run hot. AS soon as I turned the AC off it went bk to normal. Then I drove it around again today and got on it pretty good for a while(oil temp was at almost 225, which seems to be normal for turbo Audi's) and she was right at the halfway mark the whole time, except for a min when I started her back up but then it went bk to normal after the engine ran for about a min, maybe less.

 

By the way, thanks for all your help. Hope I'm not keeping you up...I may be able to borrow my girlfriend's sons laptop. I didnt realize I could even hook one up to my car w/o purchasing some outrageously priced software...

 

Mine sometimes heats up while it is off. It has to be one of your fans. Maybe with the temp sensor failure as well.

When my engine temp sensor failed, my temperature gauge would wonder the gauge. So it would go from cold, to overheating, to normal then slowly wonder back to cold, then jump to hot. It was erratic. But, mine failed one way a temp sensor can fail, yours might exhibit different symptoms.

I'm too tired to look now, but tomorrow I will look in the Bentley to see if they offer suggestions on how to test the engine fans. It will be a matter of simply bypassing the switch and relay and jumping it to the battery. Also, google output tests for the vag-com. See if there is anything in there for testing the AC fan relay.

 

The thing that's got me crazy is wondering if the issue thats causing me to overheat now with the AC on, is what caused me to have 2 hoses go bad in the first place, or if its just a coincidence. All I can tell you for sure, is that when I drive with the AC OFF, it doesnt overheat...

 

My guess would be that your car was staring to overheat, causing the pressure and temperature to build in the cooling system and busted a hose. You didn't see the car warming up because who really drives around watching the temp gauge all day. You noticed once the hose burst. You got the hose fixed then it began to overheat a second time and killed off the hose that was stressed from the 1st time it overheated.

All this probably began sometime in the past when one of your fans failed, or the fan relay. But that fan wouldn't be needed until recently now that it has been super hot out all the f-ing time. So, with the increase in heat, and the failure of the fan/relay. Your troubles began.

The temp gauge on the A6 is a calibrated gauge. Meaning it will read at the 12 o-clock position 90% of the time. The engine might be 170-210 (just guess on the range) degrees yet it still stays at 12 o-clock. It is not until it get 210+ that the gauge begins to climb up closer to 1 0-clock. But by that time, the engine is getting way to hot and can start to cause issues if it stays that hot for a while. Our oil temp gauge is not calibrated, so it fluctuates more closely to the real oil temperature.