How to Install an Aa Oo Gah Horn
 

Here is my first how to. I hope it helps..

I didnt want to replace my stock horn I just wanted to add an old fashioned Aa Oo Gah horn to my HHR. My dad bought be the Wolo Fun Horn Aa Oo Gah for Xmas so I decided to install it.

I found a pretty decent location in the fron corner on the passenger side:
https://www.chevyhhr.net/gallery/fil...9/IMG_3055.JPG

There was a pre-existing hole which ligned up pretty well with the horn mounting bolt:
https://www.chevyhhr.net/gallery/fil...9/IMG_3050.JPG

That was the easy part.
I now need to route the power to a switch on the inside. There is a pretty good post here on getting wires throught the firewall. Basically you take about an 8" - 10" piece of a wire hanger and punch it through the rubber gasket right by the steering wheel. See red wire in picture:
https://www.chevyhhr.net/gallery/fil...9/IMG_3047.JPG
Give it some pressure as it has to go through the rubber and then matting on the inside. You will find it over to the left under the dash. It usually pokes through the matting but you can re-route the wire up behind it:
https://www.chevyhhr.net/gallery/fil...9/IMG_3045.JPG
Here are some other shots of routing the wire in the engine compartment:
https://www.chevyhhr.net/gallery/fil...9/IMG_3054.JPG
https://www.chevyhhr.net/gallery/fil...9/IMG_3048.JPG
I ran a ground wire right to the body:
https://www.chevyhhr.net/gallery/fil...9/IMG_3049.JPG

On the inside I decided to add an additional fuse. When I had my XM installed the installer tapped a power line which I had changed so I solder an in-line fuse holder back on that line and routed it to a switch under the steering wheel:
https://www.chevyhhr.net/gallery/fil...9/IMG_3056.JPG

I used a Radio Shack Pushbutton switch #275-618:
https://www.chevyhhr.net/gallery/fil...9/IMG_3043.JPG

That was pretty much it.

Now I will add it did not sound very good. I think I have seen references to it sounding like a sick cow. I started thinking that the original Klaxon horns were 6v and it sounded to me like the motor was running to fast and it was too high of a pitch. I did some research and found a reference to adding a 1 or 2 ohm resistor in series with the horn.

I picked up a package of 1 Ohm Wirewound resistors at Radio Shack. Part # 271-131. About .99.

I first tried just one and it sounded pretty good but that was without the car running. It was still fast when getting current from the alternator, so I wired in both. so 12v+ --- 1 ohm --- 1 ohm --- Wolo Horn --- 12v-.

Now when I am driving the horn sounds awesome. When just on battery it is not quite right but I really only use it when the engine is running.....

There is also an adjusting screw on the top of the horn, I read about someone adjusting it and I did back it off a bit but I'm not sure if that does anything or not.

Hope this is helpful.

Nice how to.
I cheated on mine, it is where the original horn WAS, I only have one horn Aaaooogah.

Did you use a relay? Otherwise, the push button switch you used is not rated to handle the amperage of the horn. It may melt.

The switch is rated at 3amps at 125VAC, so I just kind of assumed that it would handle 3amps at 12VDC. Especially since it is only short bursts that it is getting pressed. I'll keep an eye on it though....

Watch those resistors, too. You're dropping about 18 watts across resistors that were probably rated for only 1/2 watt each. It sounds like the resistors are dropping it down to 6 volts, but they won't last long at that amperage.

according to Radio Shack they are rated at 10W 750V. I didnt do any of the math I was mostly guessing and experimenting...

I'll dig out my trusty calc and run it all through Ohms Law and see where it stands.

Thank you for the heads up on this...

You should be okay. Two 10W resistors in series should be good for 20W, so 18W shouldn't be a problem. Keep an eye on that momentary switch, though. A switch that's rated at 3A should be good to 3-4A, but a relay would be a worthy upgrade.

Anyone know where the original equipment horn is located ? Sounds kinda pharty on my car, like there is only one horn. If I knew whether it is a "High" or a "Low" note horn, a horn of the complimentary note could probably be added to achieve a harmonious sound.

That is what I want to do, were is the orginial horn?

It's behind the drivers side wheel well liner. A pain to get to unless you take off the wheel.