DS4 Heater Blower stops working

[Mart7379]

Hi Everyone,
Looking for a little bit of help. My wife owns a DS4, just recently shes been complaining that the Heater blowers are not working properly. She has explained it to me but in confusing terms.......

When she 1st starts the car on a cold morning. She switches the blowers on full blast to clear the windscreen, they will continue to blow until she turns them off completely. They will then stop working, and regardless of what speed she then selects to start them back up they will not come back on. The only time they will start working again is if the car has been sat for a few hours with the engine switched off.

I initially thought it to be the Fan motor, but the more I think about it, I am thinking it is the resistor. On the DS4 to start the windscreen blowers you hit 1 button and it goes full speed straight away (does it bypass the resistor) to control the speed for the comfort blowers you have to increase/reduce the speed on the speed control buttons?

If someone has had this exact problem and resolved it, please let me know how and what you did to fix it. Would rather not replace something that doesn't need replacing.

[GiveMeABreak]

There could be several possibilities without further diagnostics.

These have a heater motor control module that is essentially a large resistor that controls the actual blower motor (there is only one blower motor). It is designed to increase the speed of the fan gradually to the required speed. When this starts to fail you may get symptoms of 'all or nothing'.

The demist function just tells it to go at full blast and at the same time adjusts the flaps to direct the air distribution to the windscreen and front side windows.

If it was the climate control panel I think other controls wouldn't be working, so I suspect it is the heater motor control module.

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[Mart7379]

Would a standard universal OBD reader tell me where the problem is or would I need to have it plugged in to specialist diagnostic equipment?

[Mart7379]

Once she switches the blowers off, she is unable to start them again, the only thing that remains on is the digital temperature she had it set to. If it is the heater control module a brief look for the correct part is approx £160

[GiveMeABreak]

Generic OBDII readers are only able to read basic codes and rarely the constructor-specific faults codes. They won't be able to provide live data tests in many cases - it all depends on the reader you are using. Ideally you need a garage with a professional level diagnostic tool to see if you have a fault code reported or to test the system responses when being operated.

In most similar cases where I described the all or nothing scenario it us usually the control module that fails. Water moisture and temperature can also affect the system, as if the blower motor has residual moisture it can cause the motor to stick, and as the control motor is designed to spin up the fan slowly, it may not always have enough 'welly' to get the fan blades moving.

Always a good idea to leave the climate control on AUTO all the time - just change the temperature as needed and leave the system to do the job, so that the Air Conditioning system is able to remove moisture from the interior of the vehicle and the heating system components and reduce the risk of dampness causing the issues.

[GiveMeABreak]

Once she switches the blowers off, she is unable to start them again, the only thing that remains on is the digital temperature she had it set to. If it is the heater control module a brief look for the correct part is approx £160

Officially they are more likely to be from £183 to £205 from your dealer but will depend on the correct module as there are several types.

They can be bought for less (Valeo do one for about £46) but always get a decent branded one and not a cheap Chinese copy. It's a bit of a gamble though as a diagnostic will probably cost you £120 from your dealership to determine if this is the fault.

[Mart7379]

I will suggest to her to have the climate control on Auto and see if it affects anything or improves the climate control......

Thanks for your help.

[Mart7379]

just to also Clarify, the name of the part is 'Heater Blower control Module' and not a heater blower motor. or 'resistor' Whilst i know you offered to find the correct part for a donation I'm pretty skint at the moment so wouldn't expect a freebie.

[GiveMeABreak]

There are 2 types of modules that have different functions.

One is the 'Air Heating Resistance':- this is not the module we are talking about as this module helps heat the air when the car is first started in colder temperatures to speed up demisting.
The second is the the called the heater blower control module or the blower motor control module (the name varies) and is the main resistor that controls the blower motor fan speed.