ARB compressor relay getting too hot

We’ve got an ARB CKMA12 compressor fitted in our 2006 Landcruiser and from the time we bought it in 2007 it hasn’t been the best. Whenever we use it to inflate the tyres it will stop after a bit of constant use – it will stop before four tyres are topped up from 28lb to 38lb pressure.

At first ARB thought it was a dodgy solenoid and we replaced that a couple of times. Then we were told it might be due to low voltage so we only use it now with the engine running. Last weekend I used it to inflate two of our caravan tyres and it stopped half way through the second one.

After it stopped I accidently touched the 40A relay that came with the compressor and it was red hot. You couldn’t hold it for more than a second. The wires coming to the relay were pretty warm as well.

The compressor is mounted in the back of the Cruiser and is fed directly from the batteries with a 6B&S cable. The only other wire in the system is the stuff that came with the compressor and that goes through a 40A maxi fuse.

So now I’m thinking that maybe the relay or the supplied wiring is stopping the compressor.

Has anyone else had this problem?

Regards
John