Heater Blowers Staying On

[Uncle Tom Cobley]

Came home tonight and the heater blowers would not switch off.
I could not control the speed or the position but the temperature worked just fine.
Tried spare key ( batteries changed on both only a few months ago ) but no luck, even when switched off and car locked the blowers still continued to run.
Then intermittently they stopped, but has soon as I opened the door on they came again ( like the start stop feature ? ) I locked up and was about to call out a rescue service but went over to the car and they had stopped so leaving it for now.
As anybody had this problem or any idea what it could be ? Mine is a 1.6 Diesel C4 Grand Picasso 2016.

[ozvtr]

My best guess is that the Picasso has "auto" air conditioning? I.E. The temperature and blower speed are set by buttons and the blower is controlled automatically.

If this is the case then the blower controller is broken. The blower draws a lot of current and failure of the speed controller is not uncommon.

PSA use a couple of different types of speed controllers. The controller will be located on one side of the air distribution box, usually accessible from either the drivers or passengers foot well (but not always). Typically it has two large gauge wires and two small gauge wires. Either on one or two electrical connectors.
If you can find it and remove it, there are plenty of after market replacements on Ebay.

[Uncle Tom Cobley]

Hi ozvtr,
Many thanks for that.
Not a lot I can do today ( fault still present ) being new years day but will give my garage a call in the morning.
I think you are correct in diagnosing the speed controller as the blowers are staying on full blast and you cannot alter the speed.
One blessing is that they do go out after about 5 minutes so not going to get battery drain.
As soon as I press the open switch on the key fob they do come on straight away on full blast though.

[Uncle Tom Cobley]

Just found a video on YT with a 2015 C4 Picasso Grand with the exact same problem as mine.
It’s the Heater Blower Resistor and is located under a panel on the drivers side footwell and is apparently an easy job.
Will give my chaps a call on Tuesday ( forgot it’s a bank holiday here in the UK tomorrow ) and see what they say and how many ££££’s

[ozvtr]

There are predominately two types of fan speed controllers. Although there may be others.

One is cylinderical-ish and is held in place by twisting it, like a bayonet light bulb. This type is distinguished by it's "porcupine like" metal heat sink.

The other is sort of block shaped, is held in by a screw and is distinguished by metal fins.

Both the genuine and aftermarket controllers tend "blow up" because of the load of the fan. So I wouldn't recommend one over the other. Although the Chinese knock-offs are cheap and easy to find.
On that note, have you checked the cabin filter? A blocked cabin filter will increase the load on the blower fan. So just in case, you could check/replace that too.

[Uncle Tom Cobley]

Fitted a new Denso Heater Blower Resistor today and all is good again.
Simple but fiddly job ( two screws holding in the unit ) .
I got mine from Autodoc and it was here within a week and cost under £60 delivered compared to £128 from Citroen so well pleased.

[CitroJim]

Excellent!