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Strange horn sound - spurratic- Sounds fine when pushing button

rbevis

NAXJA Forum User
Location
Belmont, NC
I've got a strange problem and it has put me in some funny situations a few times.

96 XJ Sport, There is a horn type sound which will go off at strange times. When I push the button on the steering wheel, both horns work and sound fine. The strange sound I am hearing is different but sounds just like a horn and is as loud as a horn. When this sound goes off it will stay on until I cut the Jeep off. The sounds stops everytime when I cut the car off.

Right now I have unplugged both horns to see if it will do it again. That way I can eliminate it as being a horn problem.

BTW, this is the gf's jeep and it is starting to get to the embarrasing point. Most obvious solution is to wait until it goes off and find out where it is coming from but she drives the car right now and I havn't been able to catch it when riding with her. We can't swap cars either...mine is a stick.

Anyone heard of something like this?
 
Sounds like a wire is shorting out up front, and closing the circuit on one horn. Could also be the horn button, but I'd think you'd hear both horns if that were the case.
 
Well, I don't know that the noise is coming from the horn because I haven't caught it in the act yet.

Also, I unplugged one horn at a time. The sound is different than either horn by itself. Either one horn is shorting and it is somehow making a different tone when it shorts or it is something like the power steering pump making a horn noise for some reason. It definately sounds just like a horn though! Very strange.
 
if you get the chance and have the ability, take some video or something of it. i have got to hear this. if can hear it suggestions will fly.
 
Update: After driving it for a day the gf said it did it again...with both horns unplugged. I have heard the noise before so I know she's not making it up. I'm just going to have to drive it and pull over when it does it to find where it's coming from.

I can take video of it but I can also tell you that I'll know what it is whenever I catch it in the act more than likely.
 
Finally caught it today. The noise is coming from the A/C system. Mainly, the expansion valve. Everything else is working ok as far as the A/C goes. I also noticed that the noise will stop as soon as the A/C is switched off. The compressor clutch is working fine. Both lines coming out of the compressor were vibrating bad but the compressor itself had no vibrations.

Anyone have any input?
 
rbevis said:
Finally caught it today. The noise is coming from the A/C system. Mainly, the expansion valve. Everything else is working ok as far as the A/C goes. I also noticed that the noise will stop as soon as the A/C is switched off. The compressor clutch is working fine. Both lines coming out of the compressor were vibrating bad but the compressor itself had no vibrations.

Anyone have any input?

I can't tell you what causes it, but the AC in the wife's DD does the same thing.

Somebody chime in with how to fix this.

The AC was not blowing as cold as I would like, so I charged it the other day--I think a little to much, even though the gauge said it was within specs. After the charge it did not blow as cold as before and the clutch kept disengaging. I released some pressure off the system and the clutch would stay engaged, but it still didn't seem to be very cold and erratically makes the "horn" noise until it is turned off. Unless I can find somehow to fix the noise and get it to blown really cold, I think I'm going to take it to a shop and have the system vacuumed and recharged....but I hate lettting anyone else work on my Jeep. Can I get something to vacuum the system myself?
 
anyone found a fix for this yet? Replace expansion valve? I don't know much about AC systems but don't want to pay someone to fix it and want the noise to stop.
 
the a/c system if overfilled, mine did the same thing after the guy before me put too much into it. Just let some out, make sure the epa isnt looking.

Fill the a/c system after a complete vacuum according to weight, not by looking at the gauges. The ambient temp and humidity will always affect the gauges so they can't be relied on.
 
Today, while it was making the noise I got out and looked under the hood. I did not have my stethescope, but the expansion valve was violently vibrating and when the AC was turned off it promptly stopped. I think maybe the noise could be caused by a partial blockage in the valve.
 
What valve are you talking about? I was told this squarish box that connects the AC lines on the firewall was called the H-Valve.

When my compressor was going (AC on) this "H-Valve" used to make a sound very similar to a horn. Actually, we were in Chicago one night and one of my friends told me to quit being a dick and to stop honking at the Taxi drivers. But I wasn't honking, I explained that it was the AC making the noise. So perhaps we are talking about the same issue! The "horn" noise would come and go as well, sometimes it would go away if I lowered the RPM's (compressor's pully spinning less)

Half year down the road, the compressor itself was now howling (bearings) whenever the vehicle was on, although it got quieter if the AC was actually on.

I replaced the compressor with a junkyard unit and had it recharged. I used new orings but one day the orings were leaking, so I haven't used the A/C since as it is too low to allow the compressor to engage. Speaking of that, I need to get it recharged now. Some days it gets a bit warm in the cab, even with the windows wide open.
 
Jess said:
Today, while it was making the noise I got out and looked under the hood. I did not have my stethescope, but the expansion valve was violently vibrating and when the AC was turned off it promptly stopped. I think maybe the noise could be caused by a partial blockage in the valve.

This is EXACTLY the same problem I have. I put one of those R134 recharge cylinders on it and the gauge said it was good, I added a little more just to be sure. Whatdya know, the horn noise happened more frequently.

I'll let it out to just at the lower limit on the gauge and see if the problem quits. I'll report back in a day or two.
 
Ok guys, my problem is fixed. Here is what I did. Get a R134 recharge bottle with a gauge at wallmart. It is about $20 and the bottle is about the height of a 1 liter drink. Relieve pressure on the high pressure line (larger one) while the AC is on full blast. Relieve the pressure so that it is barely in the 'OK' zone of the gauge.

By doing this my AC went from cold to REALLY COLD and the noises stopped. I have about 50 miles on it with no problems. Previously it would do it every 5 min. or so.

Good luck.
 
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