2001 Citroen C5 heaters not working

more than likely fuses or relays

I have the same problem. 2003 petrol estate exclusive. Main agents Howards of Weston Super Mare say it is probably a failed chip but won't investigate any further as it will cost £800 to replace!!!!! There are other electronic faults also which they say are too expensive to locate!!! One they have looked at 3 years on the trot and failed to rectify.
Other problems are
When trying to accelerate quickly the engine dies to a tickover speed. I have to switch off and immediately turn back on - keeping the engine in gear to avoid steering/brake power loss. - very disturbing in the right hand lane of a motorway!
High level brake light failure. Howards said "It must be a fault in the wiring but you don't need it if we disconnect it"
Rear nearside break light keeps fusing. Can't locate cause.
Sometimes the engine management system fuse breaks. Always after sliding the front passenger seat backwards or forwards.

Any one else with similar problems?