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There's been a lot of debating about when our SSR engine cooling fan (or fanS) come on.
I used my tuning software to open up and examine the ORIGINAL FACTORY tuning configuration that my 04 SSR was delivered with.
It turns out, that this gets pretty complicated.
First, we have one PHYSICAL fan, but apaprently, it can operate at 2 different speeds. It must be fed by 3 wires versus 2 I'm guessing. So when the software says "Fan #1" it means the lower speed setting, and when it says "Fan #2" it means the higher peed setting.
Once you look at the fan configuration table, you see the FACTORY settings in the table below. Note that where a skilled tuner recommends otherwise, I have shown, in brackets, what the tuner sets the fields to. Also, the driver for all the temperature settings below is the engine coolant temperature.
Fan #1 on: 226 (181)
Fan #1 off: 219 (178)
Fan #1 turned on along with Air Conditioning: any temp over 185
Fan #1 turn off speed: 35 (Any speed over 35, Fan #1 turns OFF
Fan #1 run on temperature: 252 (If the coolant is at 252 or above, the Fan #1 stays on even after the ignition is turned off.
Fan #2 on: 235 (194)
Fan #2 off: 227 (190)
Both fans off speed: 90 (Above 90 mph, both fans are off unless the PCM is detecting conditions that imply engine overheating
One more complication: The "AC recirculation" and "Fan 2" are tied together by the software. There is a hard to understand field labeled "AC auto recirculation", and the software descriptino for it in EFILive is:
The PCM has a few dual purpose outputs.
The A/C auto recirculation output is also used for cooling fan #2 control.
This option changes the output for either A/C auto recirculation control or as cooling fan #2.
Only the following values may be entered for this calibration:
- Fan #2 Control
- Auto Recirculation
The factory value is Fan #2 Control, which, I THINK, means that whenever the AC is set to "recirculate" (bottom part of the middle of the 3 control knobs on the dashboard), Fan #2 is also automatically turned on.
Now, notice the little logic flaw in the above table. Fan #1 has a "turn off speed" (set to 35 mph), but Fan #2 does NOT. So, when you are at speeds above 35, the 2-stage fan will run under EITHER of the following conditions:
- coolant temperature is at 235 or more (or would be if Fan #2 shut off)
or
- You have selected the "AC recirculate" button (regardless of the coolant temperature or even the ambient temperature - you could use recirculation without AC at low ambient temperatures).
So, for all practical purposes, our fan will be running ALL the time in reasonably hot weather.
In standardized quality terms, this means it needs to be good enough to support a "100% duty cycle".
Someone (Houtex) pointed out that a number of SSR owners have suffered fan failures described as a "Fan #2 failure".
Hhhmmm.
Theory:
100% duty cycle required
Failures occurring
Maybe the fan being specified and purchased by GM just is not up to that standard?
I could see one easy way it could happen. The original GM designer and spec writer did not forsee that the SSR engine would run so hot. In the Chevy pickup trucks it came from, it probably does not. So, the fan in the pickups probably does not need a 100% duty cycle. But, if that same fan, or a similar one, is therefor specified the same way for the SSR, we have instant trouble.
It is even entirely possible that GM has not traced the logic the way I did above, and has not therefore yet realized what is going on, and why they are having to replace so many fans.
I used my tuning software to open up and examine the ORIGINAL FACTORY tuning configuration that my 04 SSR was delivered with.
It turns out, that this gets pretty complicated.
First, we have one PHYSICAL fan, but apaprently, it can operate at 2 different speeds. It must be fed by 3 wires versus 2 I'm guessing. So when the software says "Fan #1" it means the lower speed setting, and when it says "Fan #2" it means the higher peed setting.
Once you look at the fan configuration table, you see the FACTORY settings in the table below. Note that where a skilled tuner recommends otherwise, I have shown, in brackets, what the tuner sets the fields to. Also, the driver for all the temperature settings below is the engine coolant temperature.
Fan #1 on: 226 (181)
Fan #1 off: 219 (178)
Fan #1 turned on along with Air Conditioning: any temp over 185
Fan #1 turn off speed: 35 (Any speed over 35, Fan #1 turns OFF
Fan #1 run on temperature: 252 (If the coolant is at 252 or above, the Fan #1 stays on even after the ignition is turned off.
Fan #2 on: 235 (194)
Fan #2 off: 227 (190)
Both fans off speed: 90 (Above 90 mph, both fans are off unless the PCM is detecting conditions that imply engine overheating
One more complication: The "AC recirculation" and "Fan 2" are tied together by the software. There is a hard to understand field labeled "AC auto recirculation", and the software descriptino for it in EFILive is:
The PCM has a few dual purpose outputs.
The A/C auto recirculation output is also used for cooling fan #2 control.
This option changes the output for either A/C auto recirculation control or as cooling fan #2.
Only the following values may be entered for this calibration:
- Fan #2 Control
- Auto Recirculation
The factory value is Fan #2 Control, which, I THINK, means that whenever the AC is set to "recirculate" (bottom part of the middle of the 3 control knobs on the dashboard), Fan #2 is also automatically turned on.
Now, notice the little logic flaw in the above table. Fan #1 has a "turn off speed" (set to 35 mph), but Fan #2 does NOT. So, when you are at speeds above 35, the 2-stage fan will run under EITHER of the following conditions:
- coolant temperature is at 235 or more (or would be if Fan #2 shut off)
or
- You have selected the "AC recirculate" button (regardless of the coolant temperature or even the ambient temperature - you could use recirculation without AC at low ambient temperatures).
So, for all practical purposes, our fan will be running ALL the time in reasonably hot weather.
In standardized quality terms, this means it needs to be good enough to support a "100% duty cycle".
Someone (Houtex) pointed out that a number of SSR owners have suffered fan failures described as a "Fan #2 failure".
Hhhmmm.
Theory:
100% duty cycle required
Failures occurring
Maybe the fan being specified and purchased by GM just is not up to that standard?
I could see one easy way it could happen. The original GM designer and spec writer did not forsee that the SSR engine would run so hot. In the Chevy pickup trucks it came from, it probably does not. So, the fan in the pickups probably does not need a 100% duty cycle. But, if that same fan, or a similar one, is therefor specified the same way for the SSR, we have instant trouble.
It is even entirely possible that GM has not traced the logic the way I did above, and has not therefore yet realized what is going on, and why they are having to replace so many fans.