Problem Circuit
When I got my current vehicle, the fuse for the blower motor had obviously melted out its receptacle in the fuse panel.
The previous owner had wired in an inline type glass fuse. This owners manual and factory service manual this circuit it is to be fused at 30 amps. It was/is.
This aftermarket inline fuse melted a few years into ownership, and I replaced it with another inline fuse which appeared to be much higher quality.
This one Lasted a few years and the same issue happened. I replaced the glass fuse holder with an ATC fuse with 12 awg leads and used quality crimps.
I thought the problem was solved and have been talking******about inline glass fuse holders for years.
Tonight was a bit cooler, I cranked the blower motor on high, heater blasting, and soon after, I smelled rancid burning plastic. I'd shut off the blower but smoke was already coming from the area where the ATC fuse holder resides, near the original fuse panel. Luckily I was at my destination and shut off my engine and turned my battery switch to off.
I did not have another ATC fuse holder on hand that I was willing to sacrifice from some other less important circuit, but I did have an unused ready to go MAXI fuse with 8awg leads. The original circuit is 14 or possible 12awg. I only have 20 or 100 amp fuses for this maxi fuse, instead of the 30 amp the manual calls for. I installed the 20 amp fuse, obviously.
After hydraulically crimping the maxifuse inline with 2 layers of heatshrink, I turned my battery switch back on, clamped my Craftsman DC ammeter over the 8 awg cable, turned on the ignition, zeroed the meter with blower motor off. Then turned on the ignition, engine off.
12.44 battery voltage at time of test
low speed fan: 4.52 amps and read 12.08 volts probing the maxifuse and nearby clean ground.
Med speed fan: 6.73 amps and read 11.90 volts """
highspeed fan: 10.04 amps and read 11.59 """"
Max speed fan: 14.22 amps and reads 11.26 """"
These numbers kind of say to me that the blower motor is not failing, but the fact that this circuit has been recurring problem over the last decade, on the same blower motor says something else, what I do not yet know. Years ago I noticed that the blower motor had been replaced before my ownership. There were some obviously non factory crimps on the power leads. I redid them with quality crimps and shrinkwrap.
The 30 amp fuse as specified for the circuit never blew all previous fuses have never blown. Always it was the fuse holder which melted. It now has a 20 amp fuse in it, and it did not blow during my tests, but the engine was not running and the blower motor did not have time to heat up the circuit much.
The fact that it is melting at the fuse holder indicates the problem is the fuse holder itself, does it not? Perhaps the whole circuit is undersized for the load from the factory. I am not the only one to have issues with this vehicle and particular circuit.
Kind of wondering if my new maxifuse holder with 8 awg leads will just move the next melting point somewhere less accessible and perhaps more dangerous.
Opinions?
The previous owner had wired in an inline type glass fuse. This owners manual and factory service manual this circuit it is to be fused at 30 amps. It was/is.
This aftermarket inline fuse melted a few years into ownership, and I replaced it with another inline fuse which appeared to be much higher quality.
This one Lasted a few years and the same issue happened. I replaced the glass fuse holder with an ATC fuse with 12 awg leads and used quality crimps.
I thought the problem was solved and have been talking******about inline glass fuse holders for years.
Tonight was a bit cooler, I cranked the blower motor on high, heater blasting, and soon after, I smelled rancid burning plastic. I'd shut off the blower but smoke was already coming from the area where the ATC fuse holder resides, near the original fuse panel. Luckily I was at my destination and shut off my engine and turned my battery switch to off.
I did not have another ATC fuse holder on hand that I was willing to sacrifice from some other less important circuit, but I did have an unused ready to go MAXI fuse with 8awg leads. The original circuit is 14 or possible 12awg. I only have 20 or 100 amp fuses for this maxi fuse, instead of the 30 amp the manual calls for. I installed the 20 amp fuse, obviously.
After hydraulically crimping the maxifuse inline with 2 layers of heatshrink, I turned my battery switch back on, clamped my Craftsman DC ammeter over the 8 awg cable, turned on the ignition, zeroed the meter with blower motor off. Then turned on the ignition, engine off.
12.44 battery voltage at time of test
low speed fan: 4.52 amps and read 12.08 volts probing the maxifuse and nearby clean ground.
Med speed fan: 6.73 amps and read 11.90 volts """
highspeed fan: 10.04 amps and read 11.59 """"
Max speed fan: 14.22 amps and reads 11.26 """"
These numbers kind of say to me that the blower motor is not failing, but the fact that this circuit has been recurring problem over the last decade, on the same blower motor says something else, what I do not yet know. Years ago I noticed that the blower motor had been replaced before my ownership. There were some obviously non factory crimps on the power leads. I redid them with quality crimps and shrinkwrap.
The 30 amp fuse as specified for the circuit never blew all previous fuses have never blown. Always it was the fuse holder which melted. It now has a 20 amp fuse in it, and it did not blow during my tests, but the engine was not running and the blower motor did not have time to heat up the circuit much.
The fact that it is melting at the fuse holder indicates the problem is the fuse holder itself, does it not? Perhaps the whole circuit is undersized for the load from the factory. I am not the only one to have issues with this vehicle and particular circuit.
Kind of wondering if my new maxifuse holder with 8 awg leads will just move the next melting point somewhere less accessible and perhaps more dangerous.
Opinions?
