dual 480c compressor/relay problem

Automotive Onboard Air Systems
1

So today i found out one of my compressors was not running.
so i started the process of elimination. i was able to determine that it is not a compressor issue. i switched the wiring around in the relays so that the compressor that was not working before was, and visa versa for the other
one.

as i kept working i checked all the positives and grounds, and switched source. that’s when i noticed that only one of the relays clicks when i flip the on switch in the cab. i clearly remember when i was installing it they are both supposed to click. even when i reversed the switched source wire the same relay clicked, but the other didnt.

im not sure whether or no the relay is the problem. but your help would be appreciated.

2

Are they separate relays or do you have the dual relay / pressure switch?

Did you check the ground on the relay?

3

I’m a little confused but if the relays were switched then it sounds like one of them is bad.

4

They are separate relays. Its the dual 480c kit hornblasters sells.

5

Like Dan said the relay is probably bad if all the connections are good.