Had the dealer install the integrated air compressor today. Went to test it while at the dealer and it kept blowing fuses. Any thoughts? They are going to order a new one to see if that is the issue, but open to guidance - not sure how many of these installs they have done.

 

Hopefully you're in good hands.

Fuses only blow when current draw on the circuit exceeds the rated amperage.

Generally speaking this can occur if the compressor is bad and/or the connections/wiring is below gauge, too long, loose, or otherwise contaminated so as to add excessive resistance to the circuit.

That all is as long as the proper amperage fuse was used in the first place

 

Hmmm...interesting reasons. Still, I think you left out the most likely reason for a blown fuse.

Although I see the possibility the compressor is US, it would not be on my top five list of assumptions. The compressor would have been tested at the factory right before boxing up and shipping out. Not an absolute certainty that it’s bad, but highly unlikely. I’m guessing that the compressor should be on its own dedicated circuit and not share with other systems in the car. Probably 20amps. So I would check first that this is indeed the case. I would also assume the fuse box schematic (the diagram in the fuse box cover perhaps) would indicate where the accessory fuse is located.

So, after confirming the correct fuse is being used and it is on the correct accessory circuit, the number one cause for a blown fuse is an electrical short. And the number one cause for an electrical short is an installation error—caused by the oily rag technician that did the work in the first place. I wouldn’t trust a dealer tech to change the batteries in my TV remote, let alone install an air compressor in my car. Telling the customer the compressor is faulty is an easy cop out.

So the customer waits another month for the new part to arrive. Another technician (hopefully) installs the new one correctly and we will never know the true cause for the blown fuse. Life goes on.

To the OP, if you know someone that is useful with a multimeter, get he/she to look at the installation. It would probably take 5 minutes figured out the problem rather than 5 weeks with the dealer.

 

You are of course absolutely right that a dead short would have the same effect on the circuit (too much current flow from an unloaded path to ground).

I guess, as skeptical as I can be with the work of other technicians I was assuming that such a blatant error wouldn't have been made or at least would have been noticed.

But alas it is certainly possible and good to note as the op could certainly look if he was so inclined.

 

The compressor is on the same circuit as the rear 12v outlet. The installation instructions worn against having anything plugged into that outlet when using the compressor. I would hope the dealer would have checked that outlet to make sure nothing was plugged in and it was functioning properly separate of the compressor.

 

Yes, on the same fuse as the outlet in the back, but the compressor is set up so when that is on, the outlet shuts itself off (PowerfulUK did a video that tested it). My guess is either a bad compressor or an installation error. Not the end of the world and will get figured out. I’m pretty used to things like this (have owned a ‘97 soft top since ‘99, so when little issues pop up sometimes it takes a few tries.

When the 20amp fuses popped they tried to put a 30 amp in next, that also popped. So hoping it’s just a bad compressor.

 

I guess I should of asked OP previously, but does the fuse blow immediately you turn the compressor on, or some time while it's running? Does it happen every time, or when it's under load conditions (actually pumping air into tire)? As DonMitsu says, also check the 12V outlet is functioning correctly and that nothing else is running on the same circuit when the compressor is running.

I googled "defender air compressor install" and came across a powerful uk video. Others have reference this outfit before but I have not looked into them. They appear to have loads of useful videos on youtube--one being the installation of the air compressor. Anyway, the air compressor being an accessory i guess it makes sense that it uses the auxiliary 12V outlet circuit as DonMitsu mentioned. However, in the vid, they show a wiring harness that comes with the kit, that splits the power between compressor and 12V outlet such that when the compressor is turned on, the outlet is disabled. That makes sense. Also, the guy at the end of the vid, measured the current draw at 14 Amps while the compressor is running. High enough to blow a fuse if anything else is drawing current from the same circuit (like charging a couple of iPhones/iPads), but fine otherwise. But that obviously should not be a problem if installed with the new wire harness.

I would also assume the JLR tech used this particular harness splitter mentioned in the video. But still worth verifying. The video went through the entire installation step-by-step (I did a lot of fast forwarding mind you) which was very useful. A few of things worth noting: the installation is quite straight forward (other than lots of panel screws); the new cable harness requires removal of existing connector terminals and inserting into new cable connector housing (this could be too advanced for your JLR tech guy though); Powerful UK guy measured 14 Amps when it was running and I think (although he didn't say) close to 0 Amps when not; and the other thing he mentioned was that one of his channel subscribers also had problem with fuses blowing when using air compressor. He gave no more details on the particular symptoms. Saying "it keeps blowing fuses" does not describe the symptom at all. It's important to know under what conditions the fse blows and when.

 

Fuse blows almost immediately (a few seconds under load at most). I’ve watched that video, very helpful, and I’ll point the dealer in that direction. Unfortunately no idea if they installed correctly or not.

 

I have a brand new 2022 Defender X and had the fuse blow today while airing up 4 tires (got to do 2) after doing some off-roading. Not sure what is going on but I plan to take it to the dealer for diagnosis if it does it again.

 

mine required a new compressor - no issues since.