Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 924/944/968 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
944s2c's Avatar
 
Join Date: May 2004
Location: pittsburgh pa.
Posts: 9
91 s2 cooling fans cycle

Hello, I have a 944s2 that has an interesting cooling fan problem.The fans run@high for about 5 seconds and then change to low for about 3 seconds.Removing the plug from the temp sensor and jumping pins 1&3 produces continuous hi speed oper ation . Jumping pins 1&2 produces hi for 8 seconds,lo for 3 seconds. I believe I have a relay issue.Can anyone shed some light on this?Thanks,Dan
Old 08-10-2004, 02:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
PorscheG96's Avatar
 
Join Date: Aug 2000
Location: $F Bay Area
Posts: 501
Send a message via AIM to PorscheG96
By jumping pins 1 and 2 you're grounding the low speed fan operation. In order for the fans to run at low speed they require two ceramic resistors to cut down on the voltage received by the fan motors. If you look under the plastic shroud at the back of your engine compartment [near the windshield wiper] you will see 2 ceramic pucks screwed to the firewall. One of those pucks will probably have leads that are corroded. You can try to brush the corrosion off or replace the faulty resistor. Your high speed fan operation [jumping pins 1 and 3] works fine because it doesn't require the resistors. When your fans run at low speed you need 2 resistors to reduce the voltage...if you only have 1 resistor working because the 2nd one is corroded the ceramic overheats and cannot reduce the voltage enough...if you touch one what is working double-time you will burn yourself. When you hear your fans cycling between high and low speeds the resistor is heating up and cooling down repeatedly.
Old 08-11-2004, 08:20 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Moderator
 
Z-man's Avatar
 
Join Date: Feb 2001
Location: NJ, USA
Posts: 8,561
Garage
I had this problem with my 944S2 twice. Once, it was a corroded contact point on the fan switch. The other time, it was a loose or broken wire going into the fan relays. Took the mechanics a lot of hours to fix, but they figured it out both times. Give the guys at Powertech in Rockaway, NJ a call - perhaps they can steer you in the right direction (973-586-3210 website: www.pwr-tech.com ) tell them Zoltan sent ya!

Note: there was a Q&A question regarding this in PANO a year or two ago - their response was that the car was operating normally.
__________________
1989 944S2 - June, 2001 - January, 2014

Visit my homepage!
<><
Old 08-12-2004, 05:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Carroll Laird's Avatar
 
Join Date: Nov 2001
Location: New Orleans, LA
Posts: 85
Your fan relay is operating as it should - it is sensing a high resistance or open condition in one (or both) of the low speed fan circuits and gives 7 sec. bursts of high speed operation for cooling. The relay will eventually wear out its contacts from doing this - this is a "limp home" mode. You need to correct the problem in the low speed circuit which is most often the resistors as mentioned above. Other problems in the low speed circuits like Z-man describes are of course also possible and a bit more "interesting" to find and fix.

Hope this helps...
__________________
Carroll
'89 S2
Old 08-12-2004, 07:05 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,567
Garage
The radiator fans have two circuits as Carroll had mentioned. The short cycling is due to a failed low speed circuit and the fans are defaulting to high speed.

Check your wires to the fan resistors, they could be fried and open due to high amperage draw or age. If wires and connectors are fine, it's possible the fan resistors are open.

On an S2 hard top, the resistors are located in the passenger side firewall in the engine compartment close to the battery, just below the windshield. You have to lift up the plastic cover to get to it.

Hope this helps.
__________________
1993 964 C2 still makes me smile
1996 318ti (280k miles)
2011 Silverado for hauling (32k miles) - SOLD
2018 Suburban Z71
Old 08-12-2004, 09:13 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
944s2c's Avatar
 
Join Date: May 2004
Location: pittsburgh pa.
Posts: 9
Thanks so much for the info everyone!Iwill check it out and let you know what I find!Thanks, Dan
Old 08-12-2004, 02:21 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
944s2c's Avatar
 
Join Date: May 2004
Location: pittsburgh pa.
Posts: 9
Is the location the same in a cab??I have a '90 s2 cab.
Old 08-12-2004, 02:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,567
Garage
I think the resistors are located in a different spot in a cab. Look for an aluminum heatsink about 5" x 3". This is where the two fan resistors are mounted. The resistor is round ceramic type with a mounting hole in the center. They have to be in a cool ventilated area for better heat dessipation or under the passenger side footwell above the glove box.
__________________
1993 964 C2 still makes me smile
1996 318ti (280k miles)
2011 Silverado for hauling (32k miles) - SOLD
2018 Suburban Z71
Old 08-12-2004, 03:12 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
944s2c's Avatar
 
Join Date: May 2004
Location: pittsburgh pa.
Posts: 9
I found the resistors under the plastic cover as was described.The lower wire connection on the inboard resistor was heavily corroded.The insulation was also burned about 1 inch down the wire.I cleaned the connections and repaired the wire , then put dielectric grease on all the connections to prevent any further problems.I want to thank everybody for your input.You guys really saved me alot of time!Thanks! Dan
Old 08-12-2004, 05:36 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,567
Garage
Glad you fixed you fan issues. Good job!
__________________
1993 964 C2 still makes me smile
1996 318ti (280k miles)
2011 Silverado for hauling (32k miles) - SOLD
2018 Suburban Z71
Old 08-12-2004, 07:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Jul 2002
Location: San Jose, California
Posts: 140
Quote:
Originally posted by Z-man
Note: there was a Q&A question regarding this in PANO a year or two ago - their response was that the car was operating normally.
I submitted that question to the PCA tech section and as you mentioned, the written response in Pano was that the car was operating normally.

However, Bill Buris of the PCA did a followup on their online version and corrected what was printed. Here's the corrected version online:

http://www.pca.org/tech/tech_qa_question.asp?id={F49B658F-B006-4D76-BD60-5566FB114E62}

I tried the solution, and it worked...

Karl.
__________________
Previously: 1991 944 S2
Currently: Something from München...
http://www.weissach.net/
Old 08-13-2004, 10:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: May 2005
Location: Melbourne, Australia
Posts: 16
Garage
Send a message via ICQ to aggerz
Hi,

I just thought i would add to this for information to help anyone struggling to find these resistors.

Please note this info relates only to '90 944S2, Cabriolet , Right hand drive.

I found them located up under the driver footwell towards the back on the fender side. it is a real mongrel of a spot to get at but if you persist and are flexible, you can get the 2 nuts off to remove the assembly. Getting it back on is fun also.

Hope that helps anyone with a RHD Cab from doing the searching i did

aggerz.
Old 12-27-2005, 04:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 05:35 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.