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I have a base 2001 boxster, and I know that the cooling fans have 2 speeds, but I believe that they always turn on together. Is this true? I noticed today that one was running, but the other did not appear to be. I received no warning light. If one fan fails, would I be sure to get a code light? Thanks!
It's most likely the resistor which is mounted inside the fender well, on the frame rail, behind the radiator.

To eliminate the possibility that the fan motor itself is bad, turn on your A/C and check to see whether the fan runs. If it runs, it's almost certainly the resistor. They tend to get hot and then crack when splashed with water from a puddle you may be going over.

The is a DIY by Bosterra in the old PPBB archives that also shows you how you can bypass the resistor by installing a temporary jumper cable between the two relays that control the fan. Those relays are located on the bottom row of the relay tray in the left footwell, just above the fuse panel.

Regards, Maurice.
[www.ppbb.com]

also the ballast resistor replacement instructions

[www.ppbb.com]
working and it was the resistor. They're a bit exposed to splash and this can cause the hot resistor to crack/go bad. I've heard this from various sources including the tech that fixed it. I've also been told and in fact it was pointed out to me that many a Boxster that has some front end work by a shop that doesn't know what it is doing will have the radiator wiring mis-routed and the resistor not (re)installed properly. In one particular case the tech showed me how the resistor was jammed in between some the plastic ducting. Not good.

Shortly after the Boxster had its resistor replaced (and a coolant tank replaced -- it finally let go) the Turbo's passenger fan quit working and I thought the same thing was wrong with it but the tech pointed out how protected the Turbo fan stuff was. Turned out the passenger side fan motor's shaft snapped and allowed the hub/fan assembly to bang up against the back of the radiator which dented the fins but didn't hole the radiator. Fix required a new electric motor, hub/blade assembly, and radiator. (Thank goodness for CPO warranty!)

Tech said he had never seen a fan motor fail like that.

FYI: Info is the radiator fans turn on low speed when the coolant temp reaches 212F and turn off when the coolant temp drops to 205F. They switch to high speed if the coolant temp rises to 216F (or under some conditions related to A/C compressor load) and stay in high speed mode until coolant temp drops to 205F.

If the A/C is on and the compressor is running the fans run at low speed all the time but will switch to high speed if the coolant temp rises to above 216F or if the A/C compressor load real high (like it might be when turning on max. A/C to cool down a hot passenger cabin).

Sincerely,

MarcW.
Ok, I just tested by turning the a/c to full cold. The compressor kicked on, and the passenger side fan was running. Nothing from the drivers side fan. Does that ensure I am looking at a fan problem and not a resister problem?

Thanks for the help!
Ok, thanks. *NM*
gedwin - 7 years ago
Tested
gedwin - 7 years ago
Ok, first, thank you for the links. Most helpful!

I put my finger on the relay and turned on the AC, and it clicked. Clicked on turnoff (obviously) also.

Jumped the relays as instructed, turned on the AC. Compressor kicked on and the fan in question (and the other) kicked on high speed. Motor temp was "cold".

Removed jumper, retested, no left fan.

I guess I will be ordering a resistor.

Thank you all!
Update
gedwin - 7 years ago
Installed the resistor Friday night. Problem solved. $106 list at dealer, got $20 off. Had no time to wait for cheaper alternative since it's a daily driver. Problem solved. Thanks all!
Re: Update
vdoubleubum - 3 months ago
Do you have the specific instructions and maybe pics of how you did this?
thanks
... replace the fan assembly.
A new fan comes with a new resistor.
You can get them aftermarket for a decent price.
Instructions here: [pedrosgarage.com]
Happy Boxstering
Pedro

Pedro Bonilla 1998 Boxster 986 - 284,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
These seem very easy and straightforward when you read them, but take on a whole different feel when you try it.
The problem is that there's not a lot of room and the wires are fairly short, so you have very little room to work.
Also, the wires are heavy gauge and you need a lot of heat from an heavy-duty soldering iron in order to get a good splice.

Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 284,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
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