Ive exactly this problem on a 2001 Y reg Xantia AGAIN, no fans air con on, then suddenly one at TOP speed..Clogzz wrote:
This looks like the low speed not working and one fan running at high speed.
With the air conditioning turned on, even with a cold engine, both fans must spin at low speed, which is very quiet.
If low speed doesn’t work, it will go to high speed when too hot, and even only one fan spinning fast is loud enough to scare the pedestrians.
Need to get the front off again and check the relays wiring.. which is most liklely what it is...
Paul