When does the fan work?

[sfarris]

Mates,

My 996 (2003) runs fine. Temp guage shows 180 or so. But when I turn it off, i smell something hot by the tires, and the fan never kicks on. Is this normal? ( i know, smells hot is nondescript.)

Thanks.

[Loren]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

[sfarris]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

Thanks Loren. I was just thinking that on my Boxster, the fan would kick on after the car was turned off. :renntech:

[KevinMac]

When you say it smells hot are you refering to the smell of coolant? If so the cap on the coolant bottle may be bad, there have been changes to the cap. Not sure where yours fits in.

[jamesgood72]

My '99 C2 always smells hot out the back after even moderately spirited driving. Which is almost every trip... It's not excessive, but certainly noticeable by anyone. Is that normal?

I don't have any RMS problems, nor any other leaking fluids. My fans kick in when first starting in the morning, and I guess, whenever they need to. Engine temp always works it's way up to 180 or so, and stays pretty close to that.

-James.

[zoomsan]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

Hi Loren,

Does Electric Fan Speed 1 equate to the "high speed" fan speed (i.e. stage 2....relays 20,22) and Electric Fan Speed 2 equate to the "low speed" fan speed (i.e stage 1....relays 19,21)?

Thanks!

[perryinva]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

Hi Loren,

Does Electric Fan Speed 1 equate to the "high speed" fan speed (i.e. stage 2....relays 20,22) and Electric Fan Speed 2 equate to the "low speed" fan speed (i.e stage 1....relays 19,21)?

Thanks!

Just the opposite. AC on is low fan mode, ie the series resisitors are switched in. They get smoking hot. >102C is high speed. Only time I've ever seen high speed is by jumpering the relays. Talk about loud fans!

[zoomsan]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

Hi Loren,

Does Electric Fan Speed 1 equate to the "high speed" fan speed (i.e. stage 2....relays 20,22) and Electric Fan Speed 2 equate to the "low speed" fan speed (i.e stage 1....relays 19,21)?

Thanks!

Just the opposite. AC on is low fan mode, ie the series resisitors are switched in. They get smoking hot. >102C is high speed. Only time I've ever seen high speed is by jumpering the relays. Talk about loud fans!

Thank you very much for the input! But, I admit I am a bit confused now. Using the OBD hack, I monitor the coolant temp and when it's > 96C, nothing happens. But, when it's > 102C, the fan kicks on, which seems to blow at the same speed & move the same amount of air as when I turn on the AC. I have swapped relays, so I believe they are OK, but have not tried jumpering them and have not been able to verify impedance (missing the test equipment).

So, be this the case, when the fan blows with the AC on or what I'm feeling @ > 102C, is it really "low fan mode"?? Or is it that the "high fan mode" kicks in at a even higher temp than 102C??

[Lerxst]

So if I want to evacuate the hot air out of the engine bay, I could turn the a/c on to run the fan?

[zoomsan]

So if I want to evacuate the hot air out of the engine bay, I could turn the a/c on to run the fan?

Sorry...I'm referring to the radiator fans. The engine compartment fan is a different beast. There's a post here on how to do a mod, if you want to manually turn on your engine bay fan....post #13

http://www.renntech.org/forums/index.php?showtopic=20479

Edited June 7, 2008 by zoomsan

[perryinva]

Electric fan, speed 1

Coolant temperature higher than 96.75° C or air conditioning switched on.

Electric fan, speed 2

Coolant temperature > 102° C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).

The electric fans for the radiators are only triggered when the engine is running.

Hi Loren,

Does Electric Fan Speed 1 equate to the "high speed" fan speed (i.e. stage 2....relays 20,22) and Electric Fan Speed 2 equate to the "low speed" fan speed (i.e stage 1....relays 19,21)?

Thanks!

Just the opposite. AC on is low fan mode, ie the series resisitors are switched in. They get smoking hot. >102C is high speed. Only time I've ever seen high speed is by jumpering the relays. Talk about loud fans!

Thank you very much for the input! But, I admit I am a bit confused now. Using the OBD hack, I monitor the coolant temp and when it's > 96C, nothing happens. But, when it's > 102C, the fan kicks on, which seems to blow at the same speed & move the same amount of air as when I turn on the AC. I have swapped relays, so I believe they are OK, but have not tried jumpering them and have not been able to verify impedance (missing the test equipment).

So, be this the case, when the fan blows with the AC on or what I'm feeling @ > 102C, is it really "low fan mode"?? Or is it that the "high fan mode" kicks in at a even higher temp than 102C??

I have a 2002 c2. Older cars may be different. On my car the AC is definitely the low speed. Easy to tell because A. The resistors are burning hot, so they are "in" the circuit. B. I've jumpered the inputs at the relay, and it is easy to tell the high speed fan vs the low speed ie resistors "out" of circuit. The 2002 and newer cars have a newer rev of the DME, and the OBD hack does not work. (BTW, I assume you mean the HVAC hack, not the OBD. if there is an OBD hack that works on newer cars, I'd like to know what it is!!) I have never been able to verify that the temp switches work. When I get a chance, I hope that my Autoenginuity software will allow me to force them on. I just haven't had time to try it out yet. I've had the car since March, and had to replace the drivers side series resistor, because it was burnt out. Noticed it when on a warm 85F day, w/o AC on , I heard the passenger side fan come on, but not the drivers side. Pulled off the bumper cover, cleaned out TONS of crap from the rads and between rad & condenser and replaced the resistor. Both fans come on with AC and when checked with jumper, but so far have never come on due to coolant temp rise! Maybe this week..it's supposed to be 100F all week.

[zoomsan]

[

Just the opposite. AC on is low fan mode, ie the series resisitors are switched in. They get smoking hot. >102C is high speed. Only time I've ever seen high speed is by jumpering the relays. Talk about loud fans!

Thank you very much for the input! But, I admit I am a bit confused now. Using the OBD hack, I monitor the coolant temp and when it's > 96C, nothing happens. But, when it's > 102C, the fan kicks on, which seems to blow at the same speed & move the same amount of air as when I turn on the AC. I have swapped relays, so I believe they are OK, but have not tried jumpering them and have not been able to verify impedance (missing the test equipment).

So, be this the case, when the fan blows with the AC on or what I'm feeling @ > 102C, is it really "low fan mode"?? Or is it that the "high fan mode" kicks in at a even higher temp than 102C??

I have a 2002 c2. Older cars may be different. On my car the AC is definitely the low speed. Easy to tell because A. The resistors are burning hot, so they are "in" the circuit. B. I've jumpered the inputs at the relay, and it is easy to tell the high speed fan vs the low speed ie resistors "out" of circuit. The 2002 and newer cars have a newer rev of the DME, and the OBD hack does not work. (BTW, I assume you mean the HVAC hack, not the OBD. if there is an OBD hack that works on newer cars, I'd like to know what it is!!) I have never been able to verify that the temp switches work. When I get a chance, I hope that my Autoenginuity software will allow me to force them on. I just haven't had time to try it out yet. I've had the car since March, and had to replace the drivers side series resistor, because it was burnt out. Noticed it when on a warm 85F day, w/o AC on , I heard the passenger side fan come on, but not the drivers side. Pulled off the bumper cover, cleaned out TONS of crap from the rads and between rad & condenser and replaced the resistor. Both fans come on with AC and when checked with jumper, but so far have never come on due to coolant temp rise! Maybe this week..it's supposed to be 100F all week.

Thanks for the advice! Will try the "temp test" on the resistor with the fans on.

I also saw your post on another topic and you mentioned that you couldn't get the car to go above 96C with sprited driving with the 100C weather we've been getting in VA. That kills me because I can maintain <96C (via the HVAC hack) with consistent highway driving, but the temp will go up to 103C in stop and go traffic on 90+ degree days.

[perryinva]

Thanks for the advice! Will try the "temp test" on the resistor with the fans on.

I also saw your post on another topic and you mentioned that you couldn't get the car to go above 96C with sprited driving with the 100C weather we've been getting in VA. That kills me because I can maintain <96C (via the HVAC hack) with consistent highway driving, but the temp will go up to 103C in stop and go traffic on 90+ degree days.

What year and model 996 do you have? I verified Lorens temps with the Streather book, but that doesn't mean that they are correct...maybe 102C is not high speed for newer models, but low speed...his book has a few errors w/regards to info for pre-face lift cars vs post facelift, but I'd be surprised on that one. 102C is like 216F..., about right for high speed kick on...but the newer cars do run cooler, so who knows. Is that with your AC on or off? Actually, wrong question, because at those temps the high speed should have already kicked in regardless! That is just way too high if the low speed fans are just kicking on. Really sounds to me like the high speed circuit or the temperature actuation isn't working on yours, doesn't it? You really need to jumper the relay base pins to be sure.

I haven't tried stop and go, ( like a Beltway or 95 backup) w/o AC, and there just is never really any S&G traffic in Richmond except 95 at 5:00, and I'm never in it. I know that if I run errands with a lot of S&G around town (lights, stop signs, etc) with AC on, my gauge goes from exactly between the 8 & 0, to a touch more on the 0, which, according to the Autoenginuity software is about 190 to 195. I haven't run errands in 100f weather w/o AC!! But if it's 80F out, like some recent mornings, I have and the temps go only a little higher...still no fans. If those AC fans are running, the hot air wash that comes out directly in front of the front wheels is scathing hot. I haven't put a thermal probe on it, but based on my work around hot air & boilers, I'd guess it is around 160 - 170...really hot. You may have a weak fan or some blockage between the rads and condenser. Like I said, after 38k miles, mine was full of crap, probably 1/4 to 1/3 blocked each side

Edited June 15, 2008 by perryinva

[BruceP]

What year and model 996 do you have? I verified Lorens temps with the Streather book, but that doesn't mean that they are correct...maybe 102C is not high speed for newer models...but the newer cars do run cooler, so who knows...

Maybe someone in the know can confirm this, but my understanding has always been that the newer cars don't run cooler so much as they report the operating temperature differently. Supposedly, the Mk. 2 cars have two sensors whose readings are averaged, and the Mk. 1 cars have only one, which is in the hotter of the two locations.

All I know is, my cooling system is now working as designed, and sitting in traffic can still send the operating temperature north of 105 C...

[zoomsan]

What year and model 996 do you have? I verified Lorens temps with the Streather book, but that doesn't mean that they are correct...maybe 102C is not high speed for newer models, but low speed...his book has a few errors w/regards to info for pre-face lift cars vs post facelift, but I'd be surprised on that one. 102C is like 216F..., about right for high speed kick on...but the newer cars do run cooler, so who knows. Is that with your AC on or off? Actually, wrong question, because at those temps the high speed should have already kicked in regardless! That is just way too high if the low speed fans are just kicking on. Really sounds to me like the high speed circuit or the temperature actuation isn't working on yours, doesn't it? You really need to jumper the relay base pins to be sure.

I haven't tried stop and go, ( like a Beltway or 95 backup) w/o AC, and there just is never really any S&G traffic in Richmond except 95 at 5:00, and I'm never in it. I know that if I run errands with a lot of S&G around town (lights, stop signs, etc) with AC on, my gauge goes from exactly between the 8 & 0, to a touch more on the 0, which, according to the Autoenginuity software is about 190 to 195. I haven't run errands in 100f weather w/o AC!! But if it's 80F out, like some recent mornings, I have and the temps go only a little higher...still no fans. If those AC fans are running, the hot air wash that comes out directly in front of the front wheels is scathing hot. I haven't put a thermal probe on it, but based on my work around hot air & boilers, I'd guess it is around 160 - 170...really hot. You may have a weak fan or some blockage between the rads and condenser. Like I said, after 38k miles, mine was full of crap, probably 1/4 to 1/3 blocked each side

Thanks alot perrinva! You're advice is really helpful. My car is a 99 C2. But, based on some of the descriptions you are saying in your post above, my car seems to be running "normal" with the exception of the low speed fans kicking on. I'll have to give a shot with jumpering out the relays to see the sound and airflow difference between low and high speed to understand what everyone else is talking about. I've already cleaned out my radiators and I think it has helped a little, but not a lot. Since I've never jumpered out the relays, can you please help provide me some guidance? How are you doing it? Are you removing the relays from the sockets and jumpering it out from there? Also, which particular sockets are you jumpering from/to? Thanks again!