Viair 400c won't kick on, strange clicking noise

Hello, first post here. I’ve installed a onboard air system from Hornblasters. The compressor worked yesterday but today it’s making a strange clicking noise when I turn it on. Any suggestions?


Firstly, check all your wiring - especially the earth/ground. If you’re absolutely sure about that then the best way to troubleshoot this kind of stuff is just to bypass the other critical switch components (e.g. pressure switch, compressor relay)

If you’ve got the all-in one blue type pressure relay/switch from Hornblasters then you won’t be able to do much else other than wiring the compressor directly to a 12V battery to make sure it runs. If that works then you need to replace the pressure switch/relay.

If your rig has separate pressure switch and separate relay for the compressor then you can bypass each in turn to see which one is at fault.

Most of the times it’ll just be a loose wire or connector.

Ok thanks, I’ll try that today

Welcome to the forum. DBO put you on the right path. It sounds like the solenoid is activating but power isn’t getting to the compressor.

So I checked everything and it still doesn’t want to work. I’ll try to explain how I have it wired up.

I have a 10g wire with 35 fuse connected to the battery, this is my power source for the whole setup. After the fuse(away from the battery) I have a 14g wire that is spliced into the 10g that goes to my switches( one for the horns, one for compressor)the 10g continues straight to the power of the pressure switch. Then I have the compressor ground and the pressure switch ground spliced and grounded solid on the frame. And the powers from the pressure switch and compressor are connected. I also checked the check valve just incase

When I originally installed it it would make this noise then kick on, now it’s just making the noise and won’t turn on.

Any help is greatly appreciated (as I am new to this haha)

Have you tried wiring the compressor straight to a 12v battery? … just to check that it runs ok.

I haven’t tried that, would I have to run a new wire or could I just use the existing 10g I have going to the pressure switch?

Doesn’t really matter what wire you use. Just make sure you wire directly from compressor to power - it’s just meant to be a quick check to see if your comp is cactus. If the unit runs you know it’ll something else in your wiring or switch gear.

What pressure switch are you using? Is the ground to the compressor a good one?
It can only be a faulty pressure switch or the ground to the compressor & if you put the positive to the pressure switch onto the positive to the compressor as DeeBeeOhh said the compressor will run.

So I hooked the power that goes to the pressure switch(blue one from hornblasters) to the compressor and it doesn’t kick on. The sound I’ve been hearing is coming from the pressure switch, I can feel it vibrating. So is the compressor shot? Is there anything else I can try? I’m pretty confident with my ground.

Thanks for all the replies

Nooooooooo unless I have read your post wrong…
The blue wire should go to a ignition fed supply eg the cigarette lighter or something that only works with the key in the ignition.

However, that said, for test purposes, you could try linking it with the Red wire that goes to the pressure switch on a temp basis, this will operate the relay in the pressure switch and then in theory your compressor should kick in?

The buzzing sound or clicking/vibration can only becoming from the relay.

Here’s what you should have at the pressure switch?
Red Wire - to Pressure switch
Black wire - to ground
Blue wire - 12v positive feed from ignition supply/ cigarette lighter
White Wire - to red wire on compressor.

If you have the wiring correct as above, it looks like you may have a dicky pressure switch!

(Possibly due to it being wired wrong at manufacturing. If the black wire & the white wire were the wrong way round inside the pressure switch then the relay could be trying to pick up the ground through the compressor causing it to switch on & off very fast causing the pressure switch to buzz.)

If I were you I would do as suggested before, touch the red wire to the from the battery onto the red wire you must have going to the compressor - the compressor should fire up!

Yes I already tried directly hooking up the compressor to the battery and it won’t kick on. I have a 18g ground for it, should I make it a 10g?

Defo 10g for ground on compressor, but something is very wrong if the compressor is not working if you connect it direct to the battery!

LOL 18 awg will NOT work for a compressor, I’m surprised that the wire didn’t melt immediately. That would prevent the compressor from getting enough power to even turn over once. 10 AWG is about the smallest wire I would use on the power side of things, although you could use 18 for the relays and controls (with suitable fusing).