Strange one, but hoping for the insight of the forum.

I went out last night to pick up one of my kids, back on the drive by about 21:15 no issues no warning lights nothing...... Go to drive the car today in the afternoon and it's dead as a dodo.

First, I thought it was the key battery, but it was actually the car battery that was completely flat. The battery was only changed two and a half years ago, so that shouldn't be an issue, but my daughter did say she could hear what sounded like a fan running late last night, after 23:00, as her bedroom is closest to the drive.

Does anyone have any ideas why the fan would be running all by itself until the battery was dead? The only thing that may be connected is that I had the a/c compressor changed just over a week ago, not sure how they are contacted, but I did see a person ask about the air con in a similar related thread.

The battery is on charge now, so if I can get the car started tomorrow, I will take it to the garage to see if any codes pop up

I have seen references to the cooling fan running when A/C is running, so there could be some connection - that would run the battery down very quickly. Otherwise I'd be looking at a faulty cooling fan relay as being the cause.

Was the fan running when you shut the vehicle down?

Is this a TDI?

Edited 5 August, 20255 Aug by Warrior193
typo

Lots of info in this thread for same symptom, hope its useful:

13 hours ago, Shuggyboatsuperb said:

Lots of info in this thread for same symptom, hope its useful:

Thanks @Shuggyboatsuperb i did find that post last night whilst digging through and it seems to match my symptoms so hopefully it’s a relatively cheap relay solution

14 hours ago, Warrior193 said:

I have seen references to the cooling fan running when A/C is running, so there could be some connection - that would run the battery down very quickly. Otherwise I'd be looking at a faulty cooling fan relay as being the cause.

Was the fan running when you shut the vehicle down?

Is this a TDI?

Thanks @Warrior193 It was several hours after the car was shut off and appears to match the problem above with the faulty relay, fingers crossed. It is the 190bhp 2.0 tdi