Yesterday when I got home from driving, I noticed that the air compressor was still running once I turned the car off. There was a small coming from the housing as well. I didn’t know which relay to pull so I got the cover off and was about to unplug it when it finally turned off. It was burning hot to the touch.

since then it has not come on again.

This may sound dumb but a run away compressor would destroy the internals would it not? As in it’s time to get a new compressor?

Any idea why it would have done that? I have recently replaced the front bags, and I suspect that the front valve body is likely leaking because it still drops in the front over night, but I definitely didn’t touch anything around the compressor.

any thoughts would be greatly appreciated.

 

More than likely it is melty inside. The piston and cylinder and aluminum and prolonged operation is not good for them. I would suspect the compressor relay got stuck. This can happen with an overworked compressor and it pulls more and more amps to work and struggle. Also the relay can fail, and not let it operate at all. Replacing the relay is something that should be done with every new compressor install or every five years, whichever comes first. Look at the fuse, you may have blown that which is why it stopped. If so, replace fuse and relay and see what happens. If nothing, then it may be internally welded/damaged. If it fires up, well maybe you dodged a bullet. FYI, even when operating normally they do get wicked hot.

 

Thank you for the info, I also feel like it has melted inside. The relay seems fine, but I swapped it with another and no change. I also used a paper clip and jumped the pins and no compressor action. The 60amp fuse is fine as well.

I have a rebuild kit for the valve block coming and I guess I should get the AMK version of the compressor? Can I use the gap tool to upgrade the software?

 

Yes, GAP can change the compressor type. Hitachi or AMK, they work the same. There is no mechanical advantage to one over the other. The Hitachi style, however, is a lot easier to service and rebuild. In fact you could rebuild the one you have and maybe get it working. Personally I would pick up another just to get things working then rebuild the one you have as a spare. Unless you dont mine the down time, in which case I would pick up a piston/cylinder kit. Keep in mind there is a small gasket at the very bottom of the cylinder and most kits are missing that - you may have to make your own if you go that route.