Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Normal Operating Temperature

Recommended Posts

I have owned a 2001 C4 Cab (7,000 miles only!) for the past few months. Now its getting warm in California, i see the engine temperature fluctuate from the 8 in 180 on the gauge, to above the 0 in 180. Is this normal ?

I vacuumed out a few leaves from the bottom corner of the radiator, but it seems to be the same.

I checked the fans when the AC was on and they both work... they seemed to blow outwards... is this normal ?

I havent heard them run without the AC on at the slow speed.. when do they kick in for the different temperatures and different speeds ?

Is there a fuse or relay to check ?

The coolant level looks fine thru the bottle.

Sounds like other folks see something similar.. but is this normal behaviour ?

Any advice ?


Link to comment
Share on other sites

Fans should come on independent of A/C operation. Assuming not enough forward speed to provide sufficient cooling airflow the fans should run on low speed as the coolant temperature rises to the first "limit", and then to high speed if the temperature continues to climb. As it certainly will on a hot day with the additional "load" of the A/C.

The airflow from the front radiator fans should be out the bottom just in front of the front wheels. If you are feeling reverse flow then it is possible the fans are installed backward, or possibly reversed voltage polarity.

From experience I can tell you that if its a hot day and you're using the A/C and the low speed has failed by the time the system reaches the higher temperature and turns on the high speed mode it is a little too late and the car will now run slightly overtemp.

Link to comment
Share on other sites

Thanks all for the replies.

I re-checked the fan air flow and it does exit thru the opening in front of the wheels. I think i just felt the back-pressure come thru the front vent openings.

I couldnt see the low speed fans enable at all when i let the car idle at the gas station.

When the temperature gauge reached near the right side of the "0" in 180, the high speed fans kicked in (while i was stopped)

The temperature is fine when im driving... its between the "8" and "0" in 180.

At stops, it slowly creeps up.

Im guessing that the low speed fans are not kicking in at all, so the high speed ones are keeping the temperature at i higher level.

Any ideas on troubleshooting the low speed issue ? It there a fuse or relay to check. ?

Link to comment
Share on other sites


I havent heard them run without the AC on at the slow speed.. when do they kick in for the different temperatures and different speeds ?


From memory:

The fans work on low speed:

Always when the AC is switched on


if the coolant temperature is >100 Celsius

The fans switch to high speed:

If the coolant temperature is >105 Celsius



Edited by umn
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.