The heater blower suddenly stopped working on my 2009 Octavia 1.4 petrol. I removed the resistor pack and bench-tested it and found it was dead. While I was at it I decided to look at the motor as it could be the reason for the failed resistor pack and sure enough, I initially couldn't turn it by hand.

 

I forced it and it eventually spun. I bench-tested it and it spun up to full speed. However, I decided I didn't want to go through all this again in a few weeks so I got a new blower and resistor pack. Installed them and very disappointingly, still nothing. I took them out and bench-tested them and they were, as expected, fine. I reinstalled them and can hear a faint click when I turn the blower switch from 0 to 1 but that's it, nothing more. All fuses are ok but I'm not 100% sure which fuse handles the blower (I think it's number 40). I tested every fuse and they're all ok.

 

Is there a relay somewhere? Can anyone shed any light on my problem? I need it working in this crappy weather.

Does the car have a rear wiper?

If so, is that also not working?

Yes, it does have a rear wiper but it is working.

Oh, OK. There is a relay that feeds fuse 40 and a few others including rear wiper.

It's the load reduction relay used during cranking, to minimise non-essential current usage.  

Would need to know more car details to look up exactly where to find it. VIN, or just exact build date if you know it.

Edited 20 February, 20251 yr by Breezy_Pete

Breezy_Pete, thank you for your help. I appreciate it.

 

The VIN is TMBDJ21Z8A2025600

No problem. The relay on that car is in position 5 of the "relay holder below the onboard power supply control unit".

It feeds the blower motor switch via fuse 40, the rear wiper via fuse 41, and goes to the light switch via fuse 49 (presumably to switch off headlights briefly if on when cranking starts, or suchlike).

The fact the rear wiper is still working suggests that the relay isn't completely dead, but the contacts may be degraded to the point that it struggles to allow enough current to spin up the blower motor from a standstill.

 

I believe the part number of this relay is 4H0 951 253, and it probably has 100 or 644 written on the top of it.

I got a replacement relay today, plugged it in and the blower is working.

 

There are signs of overload/heat staining on the two load-circuit terminals.

 

Breezy_Pete, once again, thank you very much for taking the time to help me. I very much appreciate it.

Oh, great result; thanks for reporting back. 👍

On 20/02/2025 at 08:44, Breezy_Pete said:

Oh, OK. There is a relay that feeds fuse 40 and a few others including rear wiper.

It's the load reduction relay used during cranking, to minimise non-essential current usage.  

Would need to know more car details to look up exactly where to find it. VIN, or just exact build date if you know it.

I have the same issue with on octavia combi III 5e5. Where is the relay located on this car

I don't think there is one. The fresh air blower is powered by a control unit J126, which receives a permanent 12V supply. That in turn is controlled by a LIN data connection.

The resistor have been charged, the fan been tested on 12 volt battery and the fuses checked. Only thing that i can think of it the relay or the BCM. I don’t know if the BCM can cause thr blower motor not working