308 Heater blower fan not working

[Tom309]

I hope this helps if others have a problem with the fan (especially the removal of the fan resistor!)

On a 2013 308 (P7) the heater fan was not working. Having looked at other posts about heater blowers for the C4 (C4 heater/air con not working) on this forum it seems to be a similar system to the Citroen. Note that this 308 is a dual zone automatic a/c model.

The fan supply comes from the fuse box via a relay that only energises when the engine is running. This supply goes via the red wire to the fan speed regulator (same thing as the fan resistor, but a more complicated semiconductor circuit). This supply is linked directly to the brown +fan wire (inside the speed regulator). The black fan -ve wire then returns via the control transistor inside the speed regulator to chassis (0V) by the green/yellow wire. There are also 2 small control wires going to the regulator. See attached Fan_regulator_circuit sketch.

With the engine running, I checked for a supply at the speed regulator (to ensure there wasn't a problem with the supply fuses or relay), measured red to green/yellow - about 14V, so OK.

Checked for supply to fan (brown to black), nothing!
So suspected the fan speed regulator may be the problem. Tried to remove the regulator. It's mostly hidden, so it was pulled, pushed, levered,.. No joy, but lots of frustration...

Checked on the web for any information on it's removal - nothing. Later on, I discovered that it is removed by pushing the small black tab (identified by blue arrow on picture below) to the right (opposite direction to ident. arrow!) so that it clears the white tab (red arrow). Then simply slide the regulator up (direction of yellow arrow) and then pull out.

As a spare speed regulator had been bought before my arrival, tried that, made no difference.

To eliminate the fan as a problem, an indicator bulb was connected in place of the fan. This did not light up on any fan setting.

I had read on the web that the fan may not work if some of the air flaps are stuck, so I visually checked these by removing and peering round various panels around the console. All seemed to move, but could not see if they moved to their full extent.

To confirm that fan is actually ok, 12V was then connected directly to the fan by using a battery charger. The battery charger output is 5A, so won't get the fan to full speed, but it should at least make the fan turn at lower speeds and it is current limited.
The battery charger went to current limit, but the fan didn't turn. So though, knackered fan.

Unplugged fan (red arrowed shows connector position, wiring already moved), then removed fan by pushing the black tab (yellow arrow) towards the centre of the fan and rotating the whole fan.

As I expected the fan to have a seized bearing, I tried rotating it by hand. It turned normally!! So tried powering it directly again. As soon as it was connected to the battery charger it worked Checked the fan opening in the car for anything that may have jammed the fan - nothing.

Connected the fan back into the car using the old speed regulator it continued to work. Note that at start-up there is a short delay before the fan starts to turn; there must be a soft start in the regulator.

After this checked the brushes and bearings, all looked ok, but put some spray grease on the bearings just in case. After several journeys the fan is still working.

So conclusion:
The fan seemed to have been stuck / jammed for an unknown reason, with the speed regulator shutting down its output to protect itself / the fan, so I didn't read an output voltage.
Not sure why the light bulb didn't work, may have been a dodgy replacement as I'm unsure which regulator was in use at the time.
Still puzzled about the jammed fan though...

[KlausMP]

Had the same problem yesterday afternoon on my 308SW T9 from 2017 - the fan worked in the morning going to job - but not when I left in the afternoon.

Next day, I checked the fuses - nothing wrong.
I then took off the battery for 30 min - just to make sure the electronics was reset - did not help.
Via another YouTube video, I got access to the power cables to the fan-motor after the resistors - and could measure 12V - so problem could only be the motor.
I then measures 'infinity' Ohm to the motor - so my guess was it was dead.
Then contuned the searching the internet to find good hints on HOW to get the motor out - and found among other this blog - and the strange conclusion that the motor was working after being 'inspected'.
So I decided to get access to the blower fan (not easy, but car is right-side driven, so could have been worse) - could then open the air-inlet, and thereby get my hand inside to the blower. And it rotated eassily !!
Again - having this blog in mind, I then turned on the power - and the fan was then blowing . 30 min later, all was closed again, and fan still working!!

What could be the reason? Best guess is some dirt on the comutator so that 'coal' not was having good contact. Could also be a 'dead spot' on the motor - but time will show if this was a one-timer - or something that comes back again.

/Klaus

[Tom309]

Just for info, my fan is still working (just over 4 years later)!