Idle revs go up when fan comes on!

[stoner 0]

OK, here's an odd one. My 16v idles at 1000 rpm, until it gets hot, then when the fan comes on, the idle revs go up to 1500! Then the car idles at 1500 for the rest of the journey.

 

I've also noticed that when the car is warm (water temp over 95deg), the temperature warning light flashes whenever I flash my lights, and sometimes when I use the indicators too!

 

Anyone got any ideas? Are these two problems related?

I'd appreciate any help.

 

Andy.

[vr6storm 0]

is it a 1.8 16v or a 2.0 16v????? as that might help people point you in the right direction :wink:

[stoner 0]

It's a 1.8

[spoier 0]

Try changing the blue water temp sensor.

 

Also do you have AC or have had in the past? When AC kicks on the RPMs are supposed to go up to compensate. Could be some dodgy wiring/sensors/etc to do with that.

 

Could also be a vacuum leak, bad grounds, etc.

 

Skye

[stoner 0]

Never had A/C as far as I know. It gets wierder though. Today I drove in to work, no probs with the idle as it was cold, so the fan never came on, until I had to stop at a railway crossing. This time, when the fan came on, the revs rose slightly, then settled back at 1000rpm.

 

The revs stayed at 1000rpm, until I took off the handbrake, then they went up to 1500! I put the handbrake back on, and the revs went back to 1000 again. Took off the brake again, and the revs rose again!

 

I really am not kidding!!! I really don't have a clue whats going on. could this be the wierdest problem ever seen on a C?

[stoner 0]

No-one got any ideas? :(

[dr_mat 0]

hmm

anytime revs change linked to the braking system it's either a vacuum issue, OR there's a weird voltage regulator issue on the dash - the handbrake triggers the little LED. Perhaps there's a short somewhere that's causing the ECU to go a bit bonkers.

HTH.

 

M.