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AARRGGG!!! Stupid A/C- Speedo fuse keeps blowin!!!! need electrical experts

afroman006

afroman006

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Ok check this out. On my 91 Burban (350 TBI 4L80E) the A/c fuse blows constantly. It does at random intervals, but always does it. When the fuse blows, my speedometer stops working as well and sometimes the tranny wont shift out of first. On the fuse block for that slot it says 25 Amp fuse but the PO had a 30 amp in ther and thats what I've been using, and still it blows it constantly. What could be causing this? Low freon? When the A/C does blow it is cold enough. This is frustrating the [darn] outta me b/c its the last major glitch to fix, and I've had 3 mechanics look at it to no avail. 91 burbans are frustrating, half old [darn] and half new and no one knows anything about them. If yall have any suggestions as to what to do or what the problems might be, I'm all ears /forums/images/graemlins/ears.gif. Thx
 
If a fuse is popping that quickly you likely have a short somewhere. I'd trace the wires from the compressor and look for frayed/grounding wires.
 
Im dealing with a similiar problem with the 92-pickup

When it does blow, its icy cold, so I know there's enough freon- There is such a strong drain of power, that all the dash lights and gauges, start reading wrong.

It drawed so much power that it MELTED the fuse. Yes, you heard right, it MELTED the fuse, it acutally never blew it. Strangely enough, all the park lights, and instrument cluster lights are under one fuse.

So far, all my diagnosis has linked me to a bad AC control head unit. Mine is electronically controlled- However, upon close inspection of the box, I noticed the burnt smell of electronics-, and burnt circuit board contact.

I have one that I just won a bid on EBAY. I'll let you know if that was the culprit.
 
Tracing wires is no fun and will not net you much info.
The coil inside the a/c compressor is most likely faulty getting too much resistance when hot. I'm assuming the fuse only blows when the a/c is on? If so I would disconnect the a/c compressor clutch and see if it blows within the same amount of time. If it blows randomly when the a/c is off. You need to find out what curcuits get power from that fuse and find the splice. Then you will need to split the curcuits with indvidual fuses and see which one blows. You are going to need a good manual I would recommend Helm that is where GM and other companies get their manuals.
Good luck
 
No, it doesnt randomly blow, it only does when I try to use the A/C. Every time I have gotten it back from a mechanic recently though, it has been blown, and I doubt they turn the A/C on. Another note, its only on the front A/C, my rear A/C, rear heater and rear defrost all still work great, no matter what. Thx for the help. Where can I get this Helm manual? Is the A/C coil thing an at home fix or should it be left to a pro? Thx
 
Well I think you can just go to www.helm.com or look up helm manuals on google.
As far as the a/c coil you do have to pull the front of the compressor apart. not knowing your knowlage I coulnd't really say if you could or couldn't do it. /forums/images/graemlins/thumb.gif
 
Well you shouldn't need a whole compressor. Only the engagment clutch assembly on the front of the compressor. Just for a comparison I did my buds a/c compressor on his '02 Dodge and the dealer wanted over a thousand, the parts houses wanted close to that, he ended up getting one from a wrecking yard with a warranty for like 3-400.
I'm only assuming though that the coil that engages/disengages the compressor is faulty. Did you disconnect the connector from the compressor? Did the fuse blow?
 
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