I did a search and couldn't find any answers, but I am new, young, and dumb. I keep blowing the horn fuse under the hood. I replace it, drive down the road with the a/c on and the fuse blows. I am not blowing the horn and I can't think of any othe accessory that would contribute to the cause. I am tempted to put in a 25 amp fuse and see if it still blows. Anyone with any suggestions as to the problem I would be much obliged. Thanks.

 

Do NOT put in a higher amp fuse, unless you want bigger problems. The AC and horn are on the same relay. You either have a problem with the horn or AC. Possibly the A/C clutch is going out. Check the wires for shorts, etc. try to disconnect the horn and see if it still shorts out. Just my 2 cents.

 

I replaced the fuse. I have been driving with the a/c off, luckily it's not too hot. The fuse has not blown. I am led to believe the problem is with the a/c. I have a new compressor, accumalator, and orfice tube. The pressure might be getting to high. The air blows cold until the fuse blows. I am not sure if it is a sensor in the a/c or what? My wife call this truck the money pit, because in addition to the expensive a/c repairs this summer, I have had a new clutch, axle seals, hub assembly, drag link, axle replacement. About two grand in repairs. I really hope I can find the problem on this without having to pay to have it diagnosed. BTW my abs light stays on, maybe my problem is in the control module. Obviously, I'm guessing. I just need help.

 

I had the same problem in reverse. If I blew the horn the fuse would go. It was a dead short in one of the horns. If the fuse is OK after you blow the horn, then the obvious conclusion is there is something wrong with the A/C.

 

I think the problem is in the a/c. I think it might be when the a/c gets to its operating temp. and pressure something is causing the fuse to go. I don't know if it might be the sensor on top of the accumulator or maybe the one at the high side of the line. If I thought is was for sure one of these sensors, I would just replace them both. By the way, if a relay is bad, is it just bad all the time or could it cause this problem? Thanks for the input. Sorry if I'm making such a big deal of this, but the reason I'm here is I know you all feel the same way about your truck as I do mine.

 

The hi and lo press sw's are in series and input ONLY to the PCM. Chances are if theres no external evidence of a shorted wire then the clutch coil is bad. I've seen it a number of times from new. You can test the coil but the book is calling for an amperage draw at the coil of 2.0 - 3.9 amps with volts at 11.5 to 12.5 and ambient temp of 70 deg F. It says if more than 4 amps the coil is shorted.

 

busboy, or maybe it's Mr. Busboy, I think this might be part giving me fits. Where is the clutch coil located? I will probably just replace it. It blows the fuse as the clutch is trying to engage. When it begins the cycle. That is why it is so hard to figure out why. I appreciate your help

 

The coil is located behind the compressor pulley. You do NOT have to discharge the system to change it. It can be done in situ but does require special tools. You can probably rent them. You remove the clutch first then the pulley then the coil. The clutch is shimmed to maintain an air gap of 016-031 inch so don't loose the shims on removal. I usually shoot for 25 thou. Coil is held in place with a snap ring, ensure this snap ring IS properly seated or you'll be buying another coil and pulley. Before you do this closely check the wires at the compressor it's very easy to pinch one and short one out. I just did a Honda compressor and damaged a wire you couldn't tell just by looking at it and it was only about 1/2 inch away on the compressor, very difficult to find.

 

Busboy, you were right on. The problem was an exposed wire. Luckily it was near the connector. You know how greasey the wires can become. Half a can of carb cleaner and a close inspection found it. It was just a small bit of exposed wire, but it was enough. The problem I think is with the new line that was installed. It seems to have the high pressure sensor and surrounding wires against the air hose to the intercooler. I redirected the wires, but the sensor still makes contact with the rubber connector of the two tubes. Thanks for your help. Again, it saved me a lot of time and money.
REVMARK

 

I glad you found it before you went ahead and changed the coil.