It's an A4. The coolant temp warning light keeps blinking even when cold starting at -20 Celsius, also the temp guage moves to the highest mark at startup, it does move around a bit but usually stays in the danger zone, once in a while the temp guage falls back under 110 Celsius and the light stops flashing, but these moments are rare and brief. AC does not work when the light is flashing. Any input will be much appreciated.

 

Engine temp light blinks when the coolant level is low as well. Check that if you haven't. I don't know anything about the 12v but on the 30v the first thing to try is replacing the coolant temp sensor because they are pretty cheap. Here's a diagram of your cooling system. Looks like you have a "electronic thermoswitch" as well as a coolant temp sensor.

 

havent had that problem yet

 

Coolant temp warning light = engine temp warning light.

 

Thaks a lot, I think my problem could be that electronic thermoswitch, because in sub zero temperatures as sson as I turn the ignition switch on, the temp needle goes close to 90 Celsius and that becomes the starting point. Coolant level is OK.

 

Mine did that when there was air in the system as well. But, I'd start with the coolant switch first.

 

Now this is weird!!! As soon as I told you guys, the lights went away, but the temp needle starts at about 85C, when sold starting and stays within limits, but now the other problem has increased, that is it hesitates when starting and today it stalled on me when I stopped at a stop sign, turned over fine, but won't start up. I boosted it with my pickup and it took a long time then started hesitating and then fired up. Seems like a fuel issue, but what?

 

First guess would be fuel pump. Not that hard to do. Accessible in the trunk, under trunk mat. There's a bunch of DIYs you can find. I have a fuel pump tool, but you can do it without, just a little more difficult. Have you scanned your car for codes?

Again, it's a guess, scan your car first to see what codes you get. Temp gauge still shouldn't act like it is either.

 

Haven't worked on these a4s yet but from previous mechanical experience everything he is describing sounds like either a short in the electrical system or a failing electronic item (which sometimes in itself is a short)