Refrigerant Type: 134a
Country of Origin: United States
Recently blew 30amp aux fan fuses twice. The 3rd time, all of the freon blew out of the "safety" plug of the drier. Is this related to the blown fuses? What should I be looking at before refilling the system as I am concerned this had something to do with the blown fuses. Resistor going bad?
Most likely, the fan motor is bad or there is a frayed wire shorting out.
Overheating of the condenser after the fan stops causes overpressure. So yes, that was related. You need to fix the fan first.
Edited: Wed August 07, 2013 at 12:12 PM by mk378
Thanks MK, I'll check the high and low operation of the fan as well as the resistor.
Is the compressor coil on the same fuse?
If so, the coil may be partially internally shorted.
One good idea what replacing the pressure release valve that was used for years with a high pressure cut off switch. Surprised your 94 BMW wasn't equipped with that. But prior to the EPA getting involved and R-12 was something like 25 cents a pound, who cared? BMW must have tossed in an older dryer in your vehicle. Would definitely install a high pressure cut off switch in series with the clutch coil.
Also stop up the hole with tape or something until you can make repairs. It's important to keep water, including moist air, out of the system.
Funny thing is, my dryer had the pressure relief valve AND the high pressure cut off switch attached to it. It must have worked because it stopped the compressor from working once the freon was blown out.
Anyway, I removed the aux. fan resistor to find out what the ohm reading was. Resistor is labeled: 85W at .5 ohm.
I set the ohm meter to 2K and got a reading of .001. Is this an open (defective) resistor?
Edited: Sun August 11, 2013 at 11:24 PM by eaglerider94
Not strange at all if you BMW has a cycling switch, need at least 45 PSI of static pressure before it will close to enable the compressor.
Depends on the lowest range of your ohmmeter, with a VOM 200 ohms maximum is way too high, need one with a 2 ohm ranger to read 0.5 ohms accurately, they cost more than ten bucks. You do know that its not blown open, but know that anyway, because if it was blown open, you wouldn't be blowing any fuses.
Did you try to hand spin your fan bladed? Could have a seized bearing, if it can't spin, would blow a fuse instantly, also shorted turns in the motor would do that, or a broken brush spanning two commutators. Really doesn't make much difference any way if you try to take these motors apart to attempt to repair them, redefines the meaning of throwaway. Also clarifies the meaning of that word, sh!t.
It seems like the resistor would just be in series with the motor to slow it down on low speed. No matter how the resistor might fail, it wouldn't blow the fuse. Like Nick said, check the motor thoroughly. You could connect it directly to a battery and measure how much current it uses.
What does the blown fuse look like? Blistered or slow melt? Obliterated? This should tell you the cause.
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