![]() These types of shorts can often be found by removing the door panel, untying and “breaking into” the harness, seperating the individual wires, and checking continuity (in this case to ground) while flexing them. The harness to the driver’s door is the usual suspect, becaus thet gets flexed repeatedly every tim ethe car is used. You may have a high-resistance short to ground. But if it blows a second time then you really need to figure it out (in this case, probably getting professional service of the condenser).You didn’t say the year of the vehicle, but one thing common to older vehicles is that the insulation on wires in the wiring harness that ges through the holes in the body and door becomes chafed and cracked and shorts out. For example, a circuit might have a 20 Amp fuse (or circuit breaker) and that circuit, together with several other circuits, may be protected by a 60 Amp fuse (or circuit breaker) - the idea being that each circuit has its safe limits, designed to protect both the circuit wiring and the attached equipment (like your AC) but that the circuits combined together have another much higher limit (perhaps based on service wire capacity).īottom line: If a fuse blows (or circuit breaker flips) just once then it is typically no big deal - perhaps an overload due to motor startup problems. Normally the protection closer to the device is designed to fail first and to fail more directly. If it is the other way around (meter to fuses to circuit breaker (that didn't flip) to AC) then I would definitely get things checked out. If the fuses are closer to the condenser than the circuit breaker (i.e., current flows from the meter through the circuit breaker to the fuses to the AC) then I would not be concerned at all. then that is a sign of a huge overload, which is not a good thing. If they fail on the outside - scorch marks, cracking, etc. Fuses normally fail totally on the inside. ![]() I would be shocked (and be lucky that you were NOT shocked!) if there were external signs of damage to the fuse. If anything, circuit breakers are more likely to fail over time as they are more complex (in the case of GFCI or AFCI, much more complex) devices. I am pretty sure many of the fuses in my house are the originals from 60 years ago. They are basically "sized just right" pieces of metal. Old fuses may cause a nuisance but old breakers can be dangerous.)įuses generally last a long time, though they can fail over time according to ThreePhaseEel. ![]() When they're old, maybe fuses may get a little faster to blow, but breakers can get a little slower, or may get a lot slower, or may not blow at all. (Fuses may seem old fashioned but fuses are still very reliable protection. I would not keep feeding it fuses indefinitely. ![]() I'd have replaced both fuses (you now have one new one and one old one) and if it blows again, have the condenser serviced / checked. Maybe your condenser is old, or maybe there are fuses there from an older unit that's been replace - if that's the case they may not be necessary at all (the breaker may be adequate without the supplemental fusing in the disconnect) or they may not be sized correctly, just left there from the old equipment. Years ago a lot of condensers required fused disconnects but you don't see it in recent years. If the fuse is correct for the equipment and there was an overload that blew the fuse, it's possible your condenser is on the way out but it's also possible it was a one time glitch. If the fuses are 20A and the breaker is also 20A you'd still expect the fuses to blow before the breaker in an overload condition generally fuses blow faster than breakers of the same rating in an overload. If the fuses are 20A and the breaker is 30A you'd obviously expect the fuses to blow first in an overload condition. You don't mention the size of the breaker for the condenser circuit.
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