[GuardsRedCoupe]

While working on my AC system, I noticed that only one of my radiator fans is coming on. I swapped the power connections, and the fan that was running changed. My assumption is that both fans should come on at the same time, so something is wrong with the cable. Is this true? Thanks



- Jon

Partial Post: Please Login or Register to read the full post.

[flash]

check the fuses - there are 2 - fuse number 10 and number 15

Partial Post: Please Login or Register to read the full post.

[GuardsRedCoupe]

Fuses are ok. I took it out for a good run and heated up the engine... still only one fan running, so I know something is wrong. OK, where'd I put that multimeter......

Partial Post: Please Login or Register to read the full post.

[Greimann]

Could be the fan relay or a corroded connection at the big doughnut resistors at the firewall next to the battery. Check those first.

Partial Post: Please Login or Register to read the full post.

[GuardsRedCoupe]

[quote name='Greimann' date='Aug 6 2005, 09:50 PM']Could be the fan relay or a corroded connection at  the big doughnut resistors at the firewall next to the battery. Check those first.

[right][post="8463"]<{POST_SNAPBACK}>[/post][/right][/quote]



The resistor connections are fine... How do I check the fan relay? I'm hoping it's not that... looks like a spendy relay!

Partial Post: Please Login or Register to read the full post.

[968 Cab]

Jon



There are 2 set points for the fans:

• One fan comes on when the temp gauge is at the first lower mark (8 o’clock) – I have not checked, but others have indicated this is around the 80C range

• Second fan comes on when temps rise even higher (on my car, it is close to the 2 mark @ 10 o’clock) – again others report this is around 100C range.



So you might not get both fans running in a test where the temps don’t go high enough. Since both fans are working OK, but you are not sure if it is a faulty relay, try checking when you drive in heavy city traffic. I don’t think a relay swap would even help, other than to confirm that one fan comes on during most normal driving conditions.



Check out this thread: http://www.968forums.com/index.php?showtopic=1059



Good luck!

Partial Post: Please Login or Register to read the full post.

[Greimann]

[quote name='968 Cab' date='Aug 7 2005, 09:34 AM']Jon



There are 2 set points for the fans:

• One fan comes on when the temp gauge is at the first lower mark (8 o’clock) – I have not checked, but others have indicated this is around the 80C range

• Second fan comes on when temps rise even higher (on my car, it is close to the 2 mark @ 10 o’clock) – again others report this is around 100C range.

[right][post="8471"]<{POST_SNAPBACK}>[/post][/right][/quote]

Re-check the fan function. Both fans operate simultaneously. There are two speeds at which the fans turn. Low speed is for normal cruise and AC. The high speed kicks in at the upper temperature range.

Partial Post: Please Login or Register to read the full post.

[sasilverbullet]

running the A/C should make both fans turn on (low, but on)

Partial Post: Please Login or Register to read the full post.

[GuardsRedCoupe]

Found the problem... I figured I should post it in case anyone has something similar, or when future generations google this page. <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" />



The fuse for the cooling fan was fully inserted into the receptacle, and had resistance pushing in and pulling out. However, it was not making contact on one side of the fuse so the power was not getting through. In order to fix the problem, I took apart the central electronics box and pinched the contacts together.



Taking the central electronics box apart is a little tricky.

1. Disconnect the positive terminal of the battery.
   
   
2. Unscrew the two plastic screws that hold on the central electronics box.
   
   
3. Disconnect all the harnesses underneath the central electronics. There is a latch on the end facing the front of the car that must be pulled out in order to disconnect the harnesses. Note that each harness has a letter on the plug which corresponds to its receptacle.
   
   
4. If you need to take out multiple relays, make sure you document how they went in, so you don't swap any and end up frying your central locking computer! Here's a picture for reference. (Thanks, Dave!)    
   
   
5. Once the box is out, work your way around the box pulling up the tabs so it will come apart.
   
   
6. Pull it apart carefully, with all the pins facing downward so they don't all fall out.
   
   
7. There are plastic insulators sandwiched together, with the conductors running between them. Take off as many insulators as you need to get to the contact in question. When you take them off, make sure to leave the conductors in the grooves in the insulators so they don't get mixed up.
   
   
8. When you find the contact, squeeze it together with a pair of pliers so the fuse will make a solid contact.
   
   
9. Put everything back together.
   
   
10. Go for a drive!
    
    

Partial Post: Please Login or Register to read the full post.

[rustech]

[quote name='968 Cab' date='Aug 7 2005, 09:34 AM']Jon



There are 2 set points for the fans:

• One fan comes on when the temp gauge is at the first lower mark (8 o’clock) – I have not checked, but others have indicated this is around the 80C range

• Second fan comes on when temps rise even higher (on my car, it is close to the 2 mark @ 10 o’clock) – again others report this is around 100C range.



[right][post="8471"]<{POST_SNAPBACK}>[/post][/right][/quote]



IIRC, this is the way my old '83 944 would operate (which wasn't a wise design). The 968 operates as Greimann described.

Partial Post: Please Login or Register to read the full post.