(Radiator) fan not working

[mad_rich]

I was chatting to my neighbour yesterday as he was fettling with his car, and he told me his rad fan was not cutting in.

 

It has dawned on me that as long as I've had my car (4 months/ 7,000 miles) I haven't heard the fan kick in. Particularly worrying in the summer heat...

 

First up, anyone know which fuse to check? (The manual doesn't say.)

[Tech1e]

Why not get it up to temperature and check to see if it operates?

[mad_rich]

Why not get it up to temperature and check to see if it operates?

 

You mean get the engine up to temperature?

 

I've been doing long motorway journeys in the summer heatwave. Would have assumed that stopping at a service station should give it cause to kick in?

[Tech1e]

Has it over heated?

[mad_rich]

Not to my knowledge - at least not according to the temperature gauge - but I guess the problem is I wouldn't know.

 

It might be merrily overheating every time I switch off, expecting the fan to kick in.

[Tech1e]

If its not over heating i'd be very surprised if the fan was faulty. It takes a lot on a diesel to get it to kick in. Do you have AC?

[mad_rich]

OK. Cheers. It just seemed strange that it's never kicked in, but I didn't realise that the fan operating would be unusual.

 

No A/C.

[giandougl]

I have never heard either of the two fans fitted to my 2005 Fabia VRS ever.

I do watch the water gauge as an indication of the water temperature rising.  

Just past 1/2 way on the dial,  is as high as it ever goes.

[tommccabevRS]

You've probably never heard it kick in because you've never been listening for it, now your neighbour has mentioned it you will be looking for it to kick in lol.

[crior]

Hi,

For fabia 1.2 azq 2003 how do I check if both fans work properly?

The big fan works and if I starts up AC the speed increases but the second fan don't start. In summer, when the outside temperature is high, the big fan starts to spin very hard and the second fan don't start. What would be the cause?

 

Thanks!

[Breezy_Pete]

The fans are wired in parallel, off the same relays and same fuses, so should operate together.

The only slight complication is that some cars may have a two-speed smaller fan, others will have a single speed one. Main fan is always two-speed as far as I know.

 

Switching on the AC should result in both fans initially running at low speed, after a variable amount of time depending on ambient temperature and quantity of refrigerant in the system. Usually only  seconds in summer. If the refrigerant pressure continues to climb, both fans will switch to high speed, or if the small fan is only single speed (just two wires going to its motor), it will continue to run while the main fan switches to high speed. 

So you've already demonstrated that your small fan doesn't work.

 

You may be able to mend it by removing it, disassembling it until you can access the motor brushes, and freeing them up if stuck.  Try 'helping' it to run with a finger flick when the other fan is running, that might show that it is fixable, if it does start to spin.

 

 

[crior]

Hi,

Unfortunately I returned with bad news,

I remove up the fan and I tested it directly from bat and  working.

What other possibilities are in this case, the relay  or the cable has been interrupted?

Thank you!

[Breezy_Pete]

Same relay works both fans so hard to see it being that. Check for 12V at the loom connector for the small fan when the large one is running.

How many wires ate there on the one you removed, just two?

[crior]

The small fan has only two connectors.

The big fan has three connectors.

It is mandatory when you start the air conditioning and the temperature gets high enough to start the second fan and two fans working together, or when AC start the second fan start automatically?

[Breezy_Pete]

When AC is switched on, both fans will start as soon as the G65 refrigerant pressure sensor tells the HVAC module that the pressure is above 9 bar.

If the pressure continues to rise, and goes above 16 bar, the main fan will switch to full speed.

Edited 19 June, 2018 by Wino

[crior]

in my situation after I start the AC the big fan passes to the second stage and the small fan does not start.

[sepulchrave]

9 minutes ago, crior said:

in my situation after I start the AC the big fan passes to the second stage and the small fan does not start.

 

Check that you have 12V at the small fan connector, if you do then the motor has failed which can happen, make sure the small fan has not seized, this also happens.

Edited 19 June, 2018 by sepulchrave

[Breezy_Pete]

Can also be that some, but not all of the four carbon brushes get stuck, not making contact, so it may not start up if the other fan is pulling down the feed voltage a bit. That's why I suggested 'helping' it to start up with a careful finger flick.

 

On my Polo, I had low-speed fan failure of the main fan - it would just cycle between off and high speed - which I fixed with an external resistor. The AC fan ran OK, I thought, but maybe slower than the one on my partner's Fabia.  But when I tested the fix, I found that my AC / small fan no longer started up when the main fan now started up at low speed. I ordered a replacement small fan off ebay but thought, I might as well dismantle the small fan to see what has happened to it. When I got inside (which is a little bit brutal) I found that two opposing brushes out of the four were stuck in place, not contacting, so it was trying to start and run on just two.  Once the other fan was starting up at low speed, there wasn't enough voltage for the small one to get going. It ran a bit slowly and unevenly when it was running before the main fan fix, louder/faster and smoother after the brushes were freed up.

It may be simpler to just replace the fan, if the voltage at the connector checks out OK. Or if you enjoy mending things, carefully open up the motor of the small fan and see what has happened.

I managed to cancel the ebay order for the replacement.

Edited 19 June, 2018 by Wino

[crior]

3 hours ago, sepulchrave said:

 

Check that you have 12V at the small fan connector, if you do then the motor has failed which can happen, make sure the small fan has not seized, this also happens.

Seized? Do you mean captive or grip /stuck ?

If that's what you wanted to say, I checked "helping" with finger flick and he spins, so isn't gripped.

Should I check the voltage at the socket when the big fan starts at second speed?
If it's ok, then I change the fan.
It's problematic if I do not have the voltage at the soket.

 

[Breezy_Pete]

Check the voltage at the socket when the big fan starts at the first speed, that's when the small fan should start. It should still have 12V when the big fan goes to high speed.

[crior]

Hi,

I started the car and the air conditioning and I checked the voltage for the soket from small fan. It seems I have no voltage on those cables.

It would have to be voltage on those cables when the big fan starts up.

Edited 23 June, 2018 by crior

[crior]

I understand that the two fans would have separate fuses.

The fuses are those from the battery?Does anyone have their diagram?

[Breezy_Pete]

No, there's a 30A blade fuse in the battery compartment fusebox that feeds (at point 51 in diagram below) a relay - J279 - in the fan control module which supplies both fans at low speed.

There's a 40A strip fuse in the same fusebox which feeds (at point 49 in the diagram below) the other relay - J513 - in the fan control module, which powers the main fan at high speed (and would also feed the small fan at high speed if it were a twin speed fan).

 

It must be a wiring or connection problem for your car, between the output of the fan control module and the connector for the small fan, or the earth connection of the fan connector.

[JWvrs25]

just to add in case its of any interest, my small fan was dead, had power but no fan movement. Large fan appeared dead as well only working on full speed every now and again with air con on. Changed small fan for new one and now both work perfectly. big one works on both low and high speeds which it didn't before.