Fuse keeps blowing out

mdsanders · Post by **mdsanders** » 04 Jun 2012, 18:06

Hello Volvo Forum,

I am a long time lurker and think this is a fantastic site. I have a question re: 1988 740 GLE.

I just had a new distributor installed by a mechanic. The car works fine now, except for a fuse that keeps blowing. It is connected to the power windows, turn signal, and power seat. I don't see how a new distributor would cause this, however, I have never had this problem before and it's curious that it would occur right after a major repair. Each time I put a new fuse in and turn the car on, the fuse will work for a few seconds then go out.

I don't have any electrical schematics of the car and am really not sure where to start. I have very little experience working with electrical systems but am willing to give it a go. Any advice?

Post by **jimmy57** » 04 Jun 2012, 22:22

I recall this scenario from a problem I had years back.
Turn off a/c, be sure it is in vent or off position as compressor works in all but off or vent.
Now check to see if fuse blows. The compressor is not on immediately, there is a time delay so the fuse will not blow for this reason until the compressor is powered.
There is a noise suppressor on compressor clutch that can blow the pwr window fuse.
If the fuse doesn't blow then you have an answer. Compressor work needed.

Post by **billofdurham** » 05 Jun 2012, 13:46

Attached are wiring diagrams for your car:

740 1988 wiring diagrams.pdf: (3.43 MiB) Downloaded 360 times

Bill.

mdsanders · Post by **mdsanders** » 05 Jun 2012, 13:54

Wow, that was the exact issue. With A/C on, the fuse would always blow. After turning the A/C to vent (there is no "off" position on my model surprisingly) the fuse was fine. I have two questions regarding this:

1) Does this have anything to do with a new distributor being installed? I never had a problem with the fuse before.

2) Will this require the replacement of a new compressor or is there another way to fix it? The A/C on my Volvo has not worked for years so I am wondering if I can do without this fix.

Thanks for your response. It really helped.

Post by **jimmy57** » 05 Jun 2012, 14:10

You can unplug the wire to the compressor. That is all you need to do if the A/C is not working.
The part that shorted in a few cases I know of was the light green square suppression piece mounted to one of the mounting bolts on the compressor. You can see the wire passes through this part.
It could be clutch coil itself shorted.