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Rear A/C Switch Burned Up

4K views 6 replies 3 participants last post by  kramerhd 
#1 ·
well today it finally happened. I've seen it before, but it finally happened to mine.
the switch got jammed slightly and then i smelled the burning smell.

So what is the root cause for this,(Beside the switch jamming.)

I've had to replace the relay a few times due to it get burned up. I've even reduced the fuse by 10amp.

I'm going to the local salvage yard to get a replacement harness and switch this week.

But what Is causing it to happen in the first place????
1999 GMC Safari AWD(138,000miles)
 

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#2 ·
The problem is GM's scare of contact relays. If you lead 10 amp or more thru a tiny copper plate inbedded i plastic, you have got this problem if a minor rise in amps happens(or lack of voltage. 120watts /12v = 10amps but 120 watt / 10v = 12amp )
Then fry!!

And as allways, dont mind my english, im a swed

Hope nobody saw me killed ohms law erlier :)
 
#4 ·
put a standard 12v car relay

It should be wired up with direkt battery voltage thru the contacts 30 and 87 and on off-regulations in coil-connections (85, 86)

I stole this from a site, it explain the baics, the blue whire in the pic is the on thats goes from the switch (and only gets some 80mA)


how you should do the couplings in you car, it's up to you. I think that the most importent is to relay hi-speed on rear AC/heater (steals 13 amp I beleve). On ordinary heater/AC hi-speed all ready got a realy

I'm fighting with my own 1995 that have no volt at allto the rears.. I'm shure it will end up with a few relay and special connections when I'm ready....
 
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