Both Radiator fans not working

rustyresto · 02-16-2011, 06:32 PM

I just recently acquired this car. It is a 2000 boxster 2.7 5 speed it has 65000 miles and I just dumped coolant out the other day. No cracked hoses or anything of that nature. I can't say that the fans were ever worked have only had it a week, but I have pulled the bumper and put power to the fans and they both work. However I got the car to the 8 on 180 when it was running and checked to see if there was power going to the fans with them unplugged i didn't have any. I was also checking the fuse box with my multimeter and it didn't show any power when i put the two leads where the fuse would be. Any IDEAs? when it overheated it was the warmest day we have had. So i don't think that the fans may have ever worked.

harryrcb · harryrcb's Garage

Quote:

Originally Posted by rustyresto

I just recently acquired this car. It is a 2000 boxster 2.7 5 speed it has 65000 miles and I just dumped coolant out the other day. No cracked hoses or anything of that nature. I can't say that the fans were ever worked have only had it a week, but I have pulled the bumper and put power to the fans and they both work. However I got the car to the 8 on 180 when it was running and checked to see if there was power going to the fans with them unplugged i didn't have any. I was also checking the fuse box with my multimeter and it didn't show any power when i put the two leads where the fuse would be. Any IDEAs? when it overheated it was the warmest day we have had. So i don't think that the fans may have ever worked.

When you say, it overheated, what temperature did the gage get to? if it only went to 180 then it's normal and the cars had issues with the coolant cap that will dump out fluid. you may need to replace it with a newer updated 04 or later also the tanks have a tendency to crack and spill fluid.(these cracks are hard to find) The fans don't kick in till around 185 I think.

rustyresto · 02-17-2011, 03:24 AM

[QUOTE=harryrcb;5851525]When you say, it overheated, what temperature did the gage get to? if it only went to 180 then it's normal and the cars had issues with the coolant cap that will dump out fluid. you may need to replace it with a newer updated 04 or later also the tanks have a tendency to crack and spill fluid.(these cracks are hard to find) The fans don't kick in till around 185 I think.[/QUOTE

It was at line past the 0 on the 180 And it thought the fans have 2 setting, Im going to go ahead and buy relays and a cap since they are cheaper parts and work from there. But what tells the fans to come on? Is it a sensor or what?

rustyresto · 02-17-2011, 03:29 AM

And by the way my eng compartment fan is not coming on ether. and when i say it got hot the temp gauge little red light didn't come on tell it yacked up the coolant and i was parked so it didn't get any hotter than that

harryrcb · harryrcb's Garage

It was at line past the 0 on the 180 And it thought the fans have 2 setting, Im going to go ahead and buy relays and a cap since they are cheaper parts and work from there. But what tells the fans to come on? Is it a sensor or what?[/QUOTE]

you are right about the 2 settings for the fan and it probably should have come on. before you buy new relays try removing then and reinstall a couple of time, sometimes you get a little build up and loose contact. cap is definitely a good idea my 04 boxster had to be replaced recently, it just gave out. the fans are controlled by the sensor and dme

rustyresto · 02-17-2011, 05:58 AM

Quote:

Originally Posted by harryrcb

It was at line past the 0 on the 180 And it thought the fans have 2 setting, Im going to go ahead and buy relays and a cap since they are cheaper parts and work from there. But what tells the fans to come on? Is it a sensor or what?

you are right about the 2 settings for the fan and it probably should have come on. before you buy new relays try removing then and reinstall a couple of time, sometimes you get a little build up and loose contact. cap is definitely a good idea my 04 boxster had to be replaced recently, it just gave out. the fans are controlled by the sensor and dme[/QUOTE]

So the 04 and up cap will work for my 2000, and you say the dme? And what sensor is it. Thanks for the help. I know there's a sensor that tells it come on just don't have a clue where to start.

rustyresto · 02-18-2011, 03:18 AM

Ok ordered the radiator cap and relays just waiting on them to come in. Still with none of my cooling fans radiator or engine working I would be lead to believe that it would be a sensor or dme that tells them to come on. But I would like to know what sensor and how to test it, also I dont even know how to check the dme or where it is .

harryrcb · harryrcb's Garage

The coolant temp sensor is on the front of the motor, drivers side, accessed from under car. DME or ECM (located in the rear trunck on wall seperating engine on drivers side behind the carpet) controlls the fans based on sensor input signals from the temp sensor, the speed of the motors are controlled by a pulse width modulation signal from the ECM which then goes through the relays to the motors.
There are 4 relays in slot 19,21(stage 1 fan1) and 20,22(stage 2 fan2) + 2 fuses c8 ,c10
Hope this helps you

Wayne 962 · Wayne 962's Garage

I remember having a conversation with Charles at LN Engineering about his low-temp thermostat. He was mentioning that the low-temp thermostat was useful, but to gain maximum efficiency, you needed to replace the temp sensor somehow, as the fans only kicked on at about 200 or 210 on a typical day. I can't recall specifics, but if your temp is only heading up to the 180 range, then I don't think any of the fans will kick on.

-Wayne

rustyresto · 02-22-2011, 03:12 AM

Thanks guys. I really hope that I don't have to buy an ECM, or a temp sensor. But my relays should be in today along with my radiator cap as well. If i do have to replace my ECM, does it have to be wiped or reprogrammed for my car?

harryrcb · harryrcb's Garage

Quote:

Originally Posted by rustyresto

Thanks guys. I really hope that I don't have to buy an ECM, or a temp sensor. But my relays should be in today along with my radiator cap as well. If i do have to replace my ECM, does it have to be wiped or reprogrammed for my car?

reprogrammed

Wayne 962 · Wayne 962's Garage

Quote:

Originally Posted by rustyresto

Thanks guys. I really hope that I don't have to buy an ECM, or a temp sensor. But my relays should be in today along with my radiator cap as well. If i do have to replace my ECM, does it have to be wiped or reprogrammed for my car?

You don't have to replace your ECU - I'd be willing to bet money on that. I'm pretty sure your issue lies elsewhere.

I'm still not sure what the issue is - if the car overheats, it will get to 250+ or so. If you're concerned, then follow my coolant bleeding procedure here: Pelican Technical Article: Boxster Coolant Replacement / Boxster Coolant Flush - 986 / 987 and that might fix the problem you have (may be a simple air bubble).

-Wayne

tholyoak · 12:06 PM

The fans are turned on and off via relays actuated by the dme based upon the engine temperature received by the dme from the coolant sensor. If your coolant sensor is reporting the temperature in the cluster this is not your problem. What is incorrect above is that the speed is NOT controlled by a pulse width modulation signal from the DME. The fan speed is a simple circuit. For high speed the full voltage is sent to the blower motors through the second stage relay (one for each fan). For low speed the voltage is sent from the stage 1 relay (one for each fan) to the fan but goes through a ballast resistor prior to the motor, reducing the voltage and thus the fans speed. The ballast resistor is a very common failure where the fans don't come on at low speed (due to increasing coolant temperatures) but do at high speed (ie if you turn on the AC). If you have access to a pst2 or piwis the fans can be turned on and off at high and low speeds to test. If they don't work at any speed it is likely the relay or the fuse (or the motors). If they only come on at high speed, it is the ballast resistor located on the fan motor.

-Todd

Wayne 962 · Wayne 962's Garage

Todd's right - I forgot that turning on the air conditioning is an excellent way to test your fans. Simply turn on the A/C and check. The fans go on high, and this doesn't use the ballast resistor (which is located near the radiator, see this article here: Pelican Technical Article: Boxster Radiator Replacement and Cleaning - 986 / 987 ). If they are not going on when they should on low speeds, then Todd's right again - the ballast resistor may be faulty.

BUT, I'm still not sure if you have a problem or not. I would check the resistors and/or the power before the resistors to see if they have failed. It's insane to think that this part costs over a $100, but it's only available through Porsche at this time. I'm sure a $1 resistor from an electronics shop would work if anyone wants to take the time to figure out what is needed. Here's the link either way: Porsche Boxster Heating & Ventilation - Page 1

-Wayne

rustyresto · 03-01-2011, 03:19 AM

Been a crazy past couple of day, the fans are coming on now. I just have not had anytime to try anything, I will test to see if they are coming on with the AC though. But they are working once again.

. THANKS a bunch guys

Wayne 962 · Wayne 962's Garage

Cool! (literally). It probably wasn't hot enough for them to come on previously...

-Wayne