Car Ciggy lighter fuse keeps blowing but never when under load ?

I very rarely use the lighter socket , except when topping up the tyre pressure with a mini compressor.
I came to do it the other day and all was dead . I located the fuse , it was blown so I replaced it. The compressor then worked fine.
Next time I came to do the same job ..the fuse had gone again. Replaced yet again , used the compressor several times , switching it on and off and no issues yet again .The compressor also has a 20A fuse in the plug end which had never blown. The fuse in the car circuit is 15A . Guess what ..next time it’s gone again ..without any usage. What’s going on here ?… any pointers to common reasons for this problem ? I suspect people will say “short circuit” but there’s no obvious damage or corrosion anywhere . Just trying to avoid getting the multimeter out and tracing wires etc.
Any help / ideas much appreciated.
Thanks in advance , Bill.

No idea, but could you simply wire a fused accessory socket direct to the battery to use with the compressor so it no longer matters whether the lighter fuse blows?

Is the cigarette lighter socket permanently live? Could something be shorting briefly as you pull the compressor plug out? Is there anything inside the socket that might intermittently short it out?

Yes the lighter is permanently live and as I said I tried plugging in the compressor and removing it several times but nothing blew. I’d quite like to get the Ciggy circuit working properly as on our annual trips to France I do charge various devices

I shorted one by dropping a 5 pence in it, as above is there anything in the socket?

Pretty sure not but I guess I should examine both sockets in greater detail. A brief look inside reveals nothing loose or obvious.