740 no air-con. fuse blown... any ideas???
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From: california
740 no air-con. fuse blown... any ideas???
I have a 92' 740 turbo, for about a year now. The air-con and fans worked originally but have stopped working. I unhooked the wires to the clutch for the air conditioning, and just used the fans. It worked briefly and then quickly blew the fuse. Now if i put in a new fuse, it blows immediately when I turn on the fans. I opened up the dash and checked out the wiring there, and I didn't see a short. Ideas of what is wrong and any possible solutions would be greatly appreciated. Thanks
-Jordan
-Jordan
no mo volvo
Joined: Oct 2010
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From: 37 North on the left coast
blowing fuses indicates a power wire is shorting to ground.... pulling up the 1992 740/940 wiring diagram now (not sharable, its on a copy protected system)
lets see, power comes off the 'positive terminal' (a bus bar under the dash) to the ignition key, through fuse 16, then a black wire goes to connector A1 (2 pin connector behind the center console, appears to be somehwere below and to the right of the heating/AC control panel)), and a black wire goes from there to the C1 connector on the back of the HVAC control panel which is intenrally wired directly to the fan speed switch,... the fan speed switch is no connect in position 0, and has 5 more outputs for position 1-5. position 5 goes directly to the fan motor (red-white wire from hvac control connector C2), positions 1-4 goes to 4 taps on the resistor pack thats on the side of the airbox near the fan motor, and sets the various speeds (various color wires on connector B1-3-5-4-6).
that resistor pack has 3 connectors on it. one has 4 pins, I would try unplugging that (with the car off), and seeing if the fan works when you start the engine and put the switch in position 5 (HIGH)... if that blows the fuse, the fan motor itself is suspect unless you can see something funky in that wiring, or maybe the resistor pack.
on that resistor pack, there are two 2-pin connectors with white-blacjk and red-white, one goes to the fan motor itself, the other goes to C2 on the speed switch and to the main HVAC control big connector "A1'. I'd carefully inspect all that wiring.
oh, has an aftermarket stereo or alarm system been installed on this car? alarm system installers are awful, so are many car stereo installers. they often butcher wiring in random ways.
anyways, if you end up replacing the fan motor (a LOT easier on a 740 than it is on a 240!!!), also replace that resistor pack.
lets see, power comes off the 'positive terminal' (a bus bar under the dash) to the ignition key, through fuse 16, then a black wire goes to connector A1 (2 pin connector behind the center console, appears to be somehwere below and to the right of the heating/AC control panel)), and a black wire goes from there to the C1 connector on the back of the HVAC control panel which is intenrally wired directly to the fan speed switch,... the fan speed switch is no connect in position 0, and has 5 more outputs for position 1-5. position 5 goes directly to the fan motor (red-white wire from hvac control connector C2), positions 1-4 goes to 4 taps on the resistor pack thats on the side of the airbox near the fan motor, and sets the various speeds (various color wires on connector B1-3-5-4-6).
that resistor pack has 3 connectors on it. one has 4 pins, I would try unplugging that (with the car off), and seeing if the fan works when you start the engine and put the switch in position 5 (HIGH)... if that blows the fuse, the fan motor itself is suspect unless you can see something funky in that wiring, or maybe the resistor pack.
on that resistor pack, there are two 2-pin connectors with white-blacjk and red-white, one goes to the fan motor itself, the other goes to C2 on the speed switch and to the main HVAC control big connector "A1'. I'd carefully inspect all that wiring.
oh, has an aftermarket stereo or alarm system been installed on this car? alarm system installers are awful, so are many car stereo installers. they often butcher wiring in random ways.
anyways, if you end up replacing the fan motor (a LOT easier on a 740 than it is on a 240!!!), also replace that resistor pack.
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maltedmilk
Volvo 240, 740 & 940
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Feb 9, 2008 08:50 AM