C5 Cooling Fan Problem

[Guest Paul Farley]

Just a helpful note:

 

My C5 cooling fan had ceased up (car overheated on the dartford bridge when I turned on the air con), fine without aircon on as I turned it off and drove home with no problems. Anyway I got hold of a new one on Ebay for £40 (bargain), fitted it and then on my next journey to work, the same happened. I had already tested all the fuses I could see and couldn't find a blown fuse (handbook doesn't mention a coooling fan fuse). I did a bit of research and discoved some heavy duty fuses under the main fuse panel which clips off. Unfortunately these were all fine, next was to unclip the cooling relay loom cover next to the fan and pull the relays and the wiring loops out (fitted with push in clips). Again a bit of corrosion on the relay but all Ok (the bottom relay switches on the fan). To cut a long story short the problem was the bottom connected of the loom had corroded so much that the + contact was all but broken (the meter read 12V but when I put a test light on it it couldn't pull any current. I fitted a new spade in the connector (bit of a git) and all is now OK.

[andymarve]

did you have to take off the bumper to get to the relays? Mine started to overheat in a ten mile tailback on the M25 carpark. have checked all fuses which seem to be ok so am thinking it might be the relays.

[techbod]

this sounds like a sticking thermostat but also could be the relays not switching between low and high speeds ( not sure if its the same as the xantia which has 3 relays in the twin cooling fan housing ) but you say the A/C cools the system? this implies the the engine cooling system fans have failed,

 

1/. change the thermostat,

2/. change the coolant temp sensor,

 

the coolant temp sensor switches the fans on at 98 degrees and if the thermostat is stuck it cant do its job hence the overheating,

 

the coolant should be changed every 2 to 3 years with long life G12 which is red and this prevents oxidisation in the system because its alloy based ( aluminium rusts/rots/furs up ) which is the main cause of engine failure ie:- head gasket.

[DaveHerns]

this sounds like a sticking thermostat but also could be the relays not switching between low and high speeds ( not sure if its the same as the xantia which has 3 relays in the twin cooling fan housing ) but you say the A/C cools the system? this implies the the engine cooling system fans have failed,

 

1/. change the thermostat,

2/. change the coolant temp sensor,

 

the coolant temp sensor switches the fans on at 98 degrees and if the thermostat is stuck it cant do its job hence the overheating,

 

the coolant should be changed every 2 to 3 years with long life G12 which is red and this prevents oxidisation in the system because its alloy based ( aluminium rusts/rots/furs up ) which is the main cause of engine failure ie:- head gasket.

Red antifreeze ? I thought it was green for C5's

[techbod]

G12 as used in AUDI long life stuff and red also lubricates the water pump,

 

the colour isn't so much important but the effects are and G12 does it for me.