Rad Fan Diagnostics

Rad Fan Diagnostics

Author
Discussion

ukkid35

Original Poster:

6,223 posts

175 months

Monday 13th May
quotequote all
I found out at a very slow Calais border control queue that I have an overheating issue

I assumed it was the thermostat sticking again, but no, it's that the fans are not coming on

I have the Joolz mod that means the fans only run if the engine revs are over 500rpm (or something like that) so that full power goes to the starter motor

However that makes diagnosing issues much more tricky

Apart from checking fuses and relays, any suggestions as to what to investigate?

Byker28i

61,869 posts

219 months

Monday 13th May
quotequote all
Fans are driven from the ECU aren't they, when to turn on. Jollz mod brought the fans in 5 degrees earlier, didn't think it had a rev limiter?


Although I've noticed that if you're idling, the alternator doesn't give enough grunt to power the fans at full speed, so I always up the revs slightly if in traffic queues and it starts creeping up.


Old thread here on suggestions on faultfinding
https://www.pistonheads.com/gassing/topic.asp?h=0&...

Billy_Rosewood

3,145 posts

166 months

Monday 13th May
quotequote all
Start the car, unplug the connector under the panel and they should both start to spin iirc. If they don't i'd start with the fuse(s?)

I vaguely remember having the issue with my first cerb (going back 11-12 years now) with a single fan and it was just a bad electrical connection. I also had a cooling chip in that car, so it required the car to be running rather than just ignition on.

gruffalo

7,560 posts

228 months

Monday 13th May
quotequote all
The connector on the temperature sender get dirty so taking it off giving the contacts a clean has always fixed mine when I have encountered this issue.

Supateg

759 posts

144 months

Monday 13th May
quotequote all
There is a harness earth front chassis, worth a check? Also make sure in the software it’s turning the fans on?



Recently cleaned mine up…

ukkid35

Original Poster:

6,223 posts

175 months

Monday 13th May
quotequote all
Initial tests have proved that the fans are powered as they do run when the temp sender is disconnected

I think I'll replace the sender, as there's no reason not to and it must be ten years old at least

I'll also check the earths, thanks for that suggestion

ukkid35

Original Poster:

6,223 posts

175 months

Monday 20th May
quotequote all
Temp sender was under reporting by 15C when at ambient according to the diags

I have added a spare temp sensor to the list of parts I will now carry at all times

notaping

280 posts

73 months

Monday 20th May
quotequote all
Also - check for cruddy connections. Temperature goes down as resistance goes up . .


ukkid35

Original Poster:

6,223 posts

175 months

Monday 20th May
quotequote all
Thanks for that, I did have a quick look for a spec sheet but didn't find one