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Heater resistor speed controller; other ways

1K views 1 reply 2 participants last post by  PNW9995 
#1 ·
I have an early build 9-5 with a non-functioning heater resistor controller. No fan speed

My options are replace with a secondhand resistor for $100 plus my labour. No warranty, could be in same boat this time next week

Replace with a new resistor for three times that much; better chances but it's the same old system.

I have tried replacing the ACC head unit; no help. ACC head is OK. Fan is good.

What I am trying to do is replace the whole lot with a stack of parallel $4 resistors. Set up as follows.

Base pack- 4 x 4ohm 100watt resistors.
Collectively this is 1 x 1ohm 400watt resistor. But this can continually run the whole fan at full startup power. About eight times the power capability as
needed. This runs lowest speed.

As more resistors are 'stepped' in, total resistance is lowered and fan speed increases.

Higher speeds are 'base pack' plus 2 x 1 ohm 100 watt, added once or twice.

This give three fan speeds; 1 ohm, 0.5 ohm and 0.2 ohm.
Lo. mid and mid-high. High speed is just a straight through run past the resistors, 0.0 ohms.

Not perfect but less annoying than no speed at all.

I had hoped to wire this to the output of the ACC head, but this is proving complex. This would, if successful, use the up/down buttons directly.

Hence the call for others who might have considered and even those who may have abandoned similar plans.
 
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#2 ·
I have an early build 9-5 with a non-functioning heater resistor controller. No fan speed

My options are replace with a secondhand resistor for $100 plus my labour. No warranty, could be in same boat this time next week

Replace with a new resistor for three times that much; better chances but it's the same old system.

I have tried replacing the ACC head unit; no help. ACC head is OK. Fan is good.

What I am trying to do is replace the whole lot with a stack of parallel $4 resistors. Set up as follows.

Base pack- 4 x 4ohm 100watt resistors.
Collectively this is 1 x 1ohm 400watt resistor. But this can continually run the whole fan at full startup power. About eight times the power capability as
needed. This runs lowest speed.

As more resistors are 'stepped' in, total resistance is lowered and fan speed increases.

Higher speeds are 'base pack' plus 2 x 1 ohm 100 watt, added once or twice.

This give three fan speeds; 1 ohm, 0.5 ohm and 0.2 ohm.
Lo. mid and mid-high. High speed is just a straight through run past the resistors, 0.0 ohms.

Not perfect but less annoying than no speed at all.

I had hoped to wire this to the output of the ACC head, but this is proving complex. This would, if successful, use the up/down buttons directly.

Hence the call for others who might have considered and even those who may have abandoned similar plans.
i just bought a used resistor from a junk yard from a car with 65k miles so figured it was almost as good as new... took mine out and inspected it and it was corroded really bad on the motherboard, connected the used one with some electrical connectors cut about 3-4 inches from the resistor and been good for well over a year now... maybe even 2 years ago, i forgot how long its been since i replaced it
 
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