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Hummer H3For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.
I just want to elaborate on the subject a little bit.
jonnieh3 is correct regarding the reason for melting. The main reason the wiring gets this hot is due to a weak connection. A weak connection that causes intermittent circuit performance which leads to sparks. Very similar to the properties of an arc welder, if you will.
Large enough loads do generate heat as well which 650Hawk mentioned. However, the reason certain fuses don't blow is simply because it hasn't reached the threshold of current conduction and its specified temp range. This is why it is important to use the correct fuse per the circuit load. Otherwise you'll burn components and not fuses.
Current = Voltage/Resistance (Ohm's law for those interested), therefore heat is not a factor but a by product. However, when conductors get hot their resistance increase which causes an additional load. This is where cooled super-conductors come into play (we'll cover that next time ).
The heat produced by this circuit is not enough to melt the solder let alone sustain the amount of time needed to melt (assuming soft lead solder which has a melting point of 374°F, even higher for lead-free solder). If that were the case, everyone's bmr/wiring harness would melt almost instantly and blow the fuse the first time it is used. In fact the insulation would burn first rather then the solder joint. What does confuse me is the 30-amp fuse that is in there . Most older European cars that share a similar circuit (voltage divider circuit) use screw terminals instead. This of course is a more costly manufacturing process and who wants that, definitely not bean counters.
Newer systems employ the use of a PWM signal instead. I'm also curious as to what the new "fix" consists of. I'll wait on the feedback from other members who will have the recall performed.
Hey guys , seems that terminal reach 316F , is that normal? , you guys have the same issue? , I am afraid it could be a fire hazard . I really appreciate your Tecnical comments
Stop reading bs posts online, it's not the connector! It's an air flow issue or corrosion in the resistor. Simple check: Take your resistor out of the hvac case, and run it at low speed for a few minutes, check temp at the resistor. Warning be careful not to touch it or you may get burned! Post the results.
Btw, I just went to the garage to get a pic of my oe resistor, that I replaced many years ago, and have/still receive monthly recall notices since, (I can't respond to a recall since my new updated replacement still works)
Take a close look at my oe resistor and you will see where the excessive heat is generated:
I pulled my replacement resistor to check condition and temp test. oe resistor replaced 7 yrs ago. Contact terminals still clean on the replacement resistor and connector, light corrosion on the resistor contacts(pic below). I also did a heat test, switching between fan speeds 1-2-3, for a few minutes, max @310°, on the replacement resistor. Let cool down and checked oe resistor, the temp hit 395° after a couple minutes. 50/50 solder melts between 360° - 420° F..
1 last temperature check, I let vehicle run around 10 minutes,blower running, fan speed on 1-2-3(fan speed 4 bypass resistor) and checked temp at connector terminals(resistor mounted).Currently it's 95° ambient, passenger door open, hvac to max hot temp, switching between 1-2-3 fan speeds, highest temp reading at the terminals/connector was 125°, switched to max cool temp, waited a couple minutes, and highest reading at the terminals/connector was 108°. Bottom line, it only takes a minute to remove the 2 screws and drop the resistor to inspect. If you see excessive corrosion and/or cracks in the ceramic heatsink(shown in the picture I posted above), replace the resistor!
Also, a picture of my resistor connector, showing the terminal I replaced, from a war injury 7yrs ago(that connector had no chance, attacked from the rear). I know plastic melts at 338°, the connector still works as intended, and no additional melted plastic since resistor replacement.
How can I jump the resistor to full speed while spare arrive
[QUOTE=hummerz;375252]1 last temperature check, I let vehicle run around 10 minutes,blower running, fan speed on 1-2-3(fan speed 4 bypass resistor) and checked temp at connector terminals(resistor mounted).Currently it's 95° ambient, passenger door open, hvac to max hot temp, switching between 1-2-3 fan speeds, highest temp reading at the terminals/connector was 125°, switched to max cool temp, waited a couple minutes, and highest reading at the terminals/connector was 108°. Bottom line, it only takes a minute to remove the 2 screws and drop the resistor to inspect. If you see excessive corrosion and/or cracks in the ceramic heatsink(shown in the picture I posted above), replace the resistor!
Also, a picture of my resistor connector, showing the terminal I replaced, from a war injury 7yrs ago(that connector had no chance, attacked from the rear). I know plastic melts at 338°, the connector still works as intended, and no additional melted plastic since resistor replacement.
[/QU
I found it burnt as expected , and I am in Saudi Arabia with temperatures about 110f outside , definitely I need the Ac , is There a way to bypass the resistor and let it run full speed always while the spare arrive ? Or this harness can be fixed ? , the resistor seems fine I checked the resistance against a drawing found and are slightly higher .
I found it burnt as expected , and I am in Saudi Arabia with temperatures about 110f outside , definitely I need the Ac , is There a way to bypass the resistor and let it run full speed always while the spare arrive ? Or this harness can be fixed ? , the resistor seems fine I checked the resistance against a drawing found and are slightly higher .
"resistance slightly higher" Looks high enough to me. Replace the terminal and resistor.
"resistance slightly higher" Looks high enough to me. Replace the terminal and resistor.
thanks for the drawing , and all the replies , is appreciated .
since spares will take a long time to arrive in saudí with the current situation , can I just bypass the resistor in a safe way ?
thanks for the drawing , and all the replies , is appreciated .
since spares will take a long time to arrive in saudí with the current situation , can I just bypass the resistor in a safe way ?
07-17-2020, 01:57 PM
Resistor temperature H3 2008 hummer
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. Most older European cars that share a similar circuit (voltage divider circuit) use screw terminals instead. This of course is a more costly manufacturing process and who wants that, definitely not bean counters.
50/50 solder melts between 360° - 420° F..
