Air horn query.

[BeeJay2]

Hi all.
I've always fitted a set of single tone air horns that I've swapped from car to car over the years, except, to my present motor, simply because the horn is very difficult to access. Anyway I arranged for my local garage to do the job & decided to make sure they were okay first, not having had them working for app 6years. Did the necessary with temp wiring etc & they didn't work? I removed the trumpet air linkage to the compressor & made a temporary connection from comp to the car battery. The comp ran but didn't sound as I'd expected it to. Hmmm! Now on the comp, the connections are clearly marked + pos & - neg which is naturally, how I've always wired them up using a relay & never had a problem. So I connected the wires again & put my finger over the comp outlet to the trumpets, it was "sucking" instead of blowing!!! As they've always worked when I've had them on my previous cars I was stunned. So because of the comp sucking, I reversed the polarity & it ran as it should.
So, neg on the comp to pos battery terminal, & pos on the comp to neg battery terminal. Test working fine, but how?
Thanks in anticipation.

 

[PEG]

Hi,could be faulty nomenclature,pipe on wrong outlet,marked up for positive ground fitment....how old is the set?

 

[BeeJay2]

The unit is probably 15yrs old, but in retrospect hardly used. there's only the one outlet. I'll ring the garage tomorrow to explain & see what their lecky says. Each time I've fitted them, I've used the feed to the original horn as the relay feed. I'll post up what he says.