PetesPonies Posted August 14, 2018 Share Posted August 14, 2018 today. I had the AC on . . click and no blower. So just looking for anything specific to these models that might be common? Other than the obvious. Another question . .is the high speed blower setting just straight to ground? I think no as there should be a limiter in that blower resistor . .but??. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 14, 2018 Share Posted August 14, 2018 If it truly is Fuse 9, as shown here, then I'd try a new fuse before going any farther. I've had them fail and a replacement last for years. But it could also be other things. For instance, the thermal limiter in the resistor pack is a known problem. They just get old and die, which kills the blower. Or, it could be that a resistor failed in the pack, which kills that speed but not other speeds. And, if the new fuse also fails then there's the question of how quickly. If immediately then you obviously have a short. But a bad motor, or one that has worn bearings such that it is dragging can pull so much current that it'll blow the fuse. In that case try different speeds to see what happens. Does that help? Link to comment Share on other sites More sharing options...
PetesPonies Posted August 14, 2018 Author Share Posted August 14, 2018 If it truly is Fuse 9, as shown here, then I'd try a new fuse before going any farther. I've had them fail and a replacement last for years. But it could also be other things. For instance, the thermal limiter in the resistor pack is a known problem. They just get old and die, which kills the blower. Or, it could be that a resistor failed in the pack, which kills that speed but not other speeds. And, if the new fuse also fails then there's the question of how quickly. If immediately then you obviously have a short. But a bad motor, or one that has worn bearings such that it is dragging can pull so much current that it'll blow the fuse. In that case try different speeds to see what happens. Does that help? I did. It was the 30A fuse. First thing I did was try another. It lasted about 20 seconds. All speeds seem to work until the fuse blows. No noise or anything from the blower motor, but that should be my first check. I thought there was a limiter in the resistors. I'll check that as well. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 14, 2018 Share Posted August 14, 2018 I did. It was the 30A fuse. First thing I did was try another. It lasted about 20 seconds. All speeds seem to work until the fuse blows. No noise or anything from the blower motor, but that should be my first check. I thought there was a limiter in the resistors. I'll check that as well. The thermal limiter is a one-shot thing, not an auto-reset unit. So, when it goes the blower is done. But, it shows that High bypasses the limiter. I'd be surprised if a bad motor would blow a fuse on a lower speed. Link to comment Share on other sites More sharing options...
PetesPonies Posted August 14, 2018 Author Share Posted August 14, 2018 The thermal limiter is a one-shot thing, not an auto-reset unit. So, when it goes the blower is done. But, it shows that High bypasses the limiter. I'd be surprised if a bad motor would blow a fuse on a lower speed. OK, well if high speed bypasses the limiter, then the motor grounded directly gives you high speed. So the motor should not draw over the 30 amps. Hmmmm Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 14, 2018 Share Posted August 14, 2018 OK, well if high speed bypasses the limiter, then the motor grounded directly gives you high speed. So the motor should not draw over the 30 amps. Hmmmm If the bearings are dry or worn such that the armature is dragging on the field, which happens, then it will draw more current than it should. On a lower speed setting that still shouldn't be more than 30 amps, but it could be on High. Link to comment Share on other sites More sharing options...
PetesPonies Posted August 15, 2018 Author Share Posted August 15, 2018 If the bearings are dry or worn such that the armature is dragging on the field, which happens, then it will draw more current than it should. On a lower speed setting that still shouldn't be more than 30 amps, but it could be on High. Agreed. Link to comment Share on other sites More sharing options...
Johns3524 Posted August 17, 2018 Share Posted August 17, 2018 Agreed. Hi guys, my 86 Began to blow fuses as well. I ended up replacing the slider switch (vacuum). It seemed to short out for some reason...works fine now... 35$ or so nos Btw, when I began to blow fuses, my a/c was cycling on and off more than usual due to low r134. When I replaced the fuse, the heater would blow fine but when a/c was turned on the fuse would Blow even with the compressor unplugged. The old vacuum sw failed internally I assumed. Link to comment Share on other sites More sharing options...
PetesPonies Posted August 17, 2018 Author Share Posted August 17, 2018 Hi guys, my 86 Began to blow fuses as well. I ended up replacing the slider switch (vacuum). It seemed to short out for some reason...works fine now... 35$ or so nos Btw, when I began to blow fuses, my a/c was cycling on and off more than usual due to low r134. When I replaced the fuse, the heater would blow fine but when a/c was turned on the fuse would Blow even with the compressor unplugged. The old vacuum sw failed internally I assumed. Since the slider is vacuum operated, has no electricity to it, how is that a problem? Now the fan switch . . . Link to comment Share on other sites More sharing options...
Johns3524 Posted August 17, 2018 Share Posted August 17, 2018 Since the slider is vacuum operated, has no electricity to it, how is that a problem? Now the fan switch . . . On my heater control the slider is the on/off control for all functions and electricity flows thru all the various contacts for the functions. It controls both electric and vacuum...and takes determination to change. Link to comment Share on other sites More sharing options...
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