Smell coming from cabin heater

[marsheng]

Originally I thought I had driven past a factory as I smelt this strange odour after about 10 minutes of driving. It's not a strong smell, however for the next 3 drives, it was there again. If I turn the cabin fan off, no problem.

It's not a burnt wiring smell but something like that. Its not a dead animal or leaves smell.

Any suggestions ?

Thanks Wallace.