compressor wires gettin' HOT

I'm running a 140/200 pressure switch, two 30 amp relays, two viairs 400c, and a switch on the dash to bypass the preasure switch. 10g froom the relays to the dash switch and 8g to the compressor power.

wires at the swtich are getting HOT and even melted a switch. anyone got a clue why? I went through and checked everything out and redid some stuff, but still a little hot and bothers me.

Suggestions?

What is the amp rating on the switch? You need at least the same size as the relays you are running.

Okay, I'll try that. I think the switch was 15amp or something. Truck came with it & an extra of the same type. Headed to the parts store now. Thanks. That would be why the wires are getting hot?

That is usually the problem.

Hey Unless you are bypassing the relays with that switch you will not see full current thru the switch. It is only a trigger(and should only see a draw of .1-.5 amps). Thats the reason you use relays. If you are running both compressors of of an 8 guage feed and they are at the rear of the truck you are not using enough thick enough wire. should be minimum of 4 guage possibly 2 guage depending on the actual amperage draw of the compressors. If you are pushing 200 psi your actual draw will be quite high.

how are you bypassing the pressure switch? I think you may be backfeeding your switch or pressure switch causing to many amps to the switch.

The switch wire shouldn't need to be very heavy as all it is a trigger wire from the relay. On remote starts and alarms they put out milliamps to relays that control ignition circuits and other high amp items. I would guess something isn't wired correctly to the relay or you are supplying too much power to the switch using the 10 gauge wire and that is why you are melting it.

Should be 8 ga direct from battery fused within 12" of battery to relay pin #30
8ga from pin #87 to positive on compressor
Pin 85 should be to good ground, using 8 ga wire to be on the safe side
Pin #86 is your positive wire from switch, you can jump this wire to both relays using pin #86. Before your switch you need a fused source 5 or 10 amps and run 16 gauge wire to switch and from switch to relay.

I would run a seperate 8 ga from battery to each relay and seperate grounds as well. There is no need for heavy gauge wire to a switch, just make sure the switch is rated for at least 10 amps if you put a 10 amp fuse in.

I would also recommend feeding your switch with an acc circuit so if you leave your switch on and your compressors kick on when you are away from your truck you don't kill your battery.

Also, why are you bypassing the pressure switch? it runs up to 200psi, which I don't think viairs are rated for any higher.

yup, they had it wired wrong. They had the switch on the #30 side of the relay instead of the #86.

Get a starter solenoid from 1990 mustang gt and use that in place of your relays. Only like $10-15 at Autozone. Ive been running 3 VIAIR 444c's and havnt had a problem since. The relays they compressors come with suck. Doing the solenoid should bring the heat down as there will be less draw.

solenoids work great but usually starter solenoids aren't designed for continuous use, they are for short bursts of high amps. They do make continuous duty solenoids though, snow plows used to use them.