Rad Fan Diagnostics

[ukkid35]

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]

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]

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]

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]

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]

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]

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]

Also - check for cruddy connections. Temperature goes down as resistance goes up . .

[ukkid35]

Thanks for that, I did have a quick look for a spec sheet but didn't find one