Audi a3 2008 radio wont turn on

Correct model radio or an aftermarket radio. Put the old radio back in to check the AC system before spending time confusing yourself.

Check Fuse's Some Makes have a fuse for the radio that is next to the hot wire near the Battery itself . Start with those first and if no solution write back telling that you have checked them and to no avail/

please test the fuse for open or dirty or corrosion or bad contact.
2) tight the wires connector very well.
3) see if the connection are propely connected and not missing
see the diagram attached.
God bless you

Have you checked the fuse?

you will need to find the wires on the back of the radio and make sure the hot wire is getting juice to it also if it is an aftermarket radio some require that the constant power be hooked up as well in order for it to work. howevwer the factory radio on most models will not need the constant power except for memory only. also if it is aftermarket radio there will be an inline fuse on the hot wire and constant. also need to check ground. no ground no power. all of that being checked and still no power u may have to break down and find a new radio

Hi

Make sure ALL your fuses are okay. Sometimes when a car stereo blows, it may blow more than one fuse. If are your fuses are okay, then your unit might be dead. Another way to test it, if you’re savvy enough, is to locate the Ground, the 12v constant, and the accessory wire. If they cannot be located by measuring, try to find a wire color code.Check this bellow site…

http://www.modifiedlife.com/car-stereo-wiring-diagrams-and-car-radio-wiring-diagrams/

When found, try to measure if the wires actually give you voltage. If they do, there may be a fuse on the actual stereo. This is common with aftermarket systems and not so much with stock. Which means you will either have to find an aftermarket unit w/ a possible kit, antenna adapter and wiring harness. This can cause you to spend more than you would like to. In this cause, try to go to ebay or a junkyard and find your EXACT radio for cheap and replace it by simply plug out and plug in.
If your wires behind the radio DON'T give you voltage, there is another fuse blown somewhere. Or (in rare cases) the the plug behind the radio may have a loose connection OR a wire might have shorted too much and caused the wire to melt in turn making it not conductive.

Let us know if you have something more to know else accept the suggestion.
Thank You for contacting Fixya.com

Yours radio has a burnt fuse in back right side of it (10A). You must extract the radio box out from dash panel in order to replace this burnt fuse. You need two special radio keys extracting tools. For Chorus and Concert AUDI radios use T10057 radio release tool:
1. Switch off all electrical equipment.
2. Remove ignition key.
3. Insert two radio release tools T10057 into slots on radio (bottom front side) until they engage.
4. Pointed ends of grips must face outwards.
5. Grasp hold of grips on radio release tool T10057 and pull radio out of dash panel.
6. Release and unplug electrical connectors at radio.
7. Press release tabs on radio and remove radio release tool T10057.
8. Replace the burnt fuse (10A) with new one.
9. Plug in all connectors.
10. Slide radio carefully into dash panel and engage it in mounting frame.

You may have the clock and radio power leads reversed. Clock needs to be on a line that is hot with key on or off...radio goes to a lead that is only hot with key on.Same goes for lead for power antenna...don't need power there unless car is on. Don't forget...I'm not there so I can only make an educated guess.
Good Luck

most aftermarket units have 2 power wires 1 for the battery and 1 for a keyed hot source,what you need to do is hook both of them up to a constant (battery) power source,be sure and include an in-line fuse.