Heater not blowing

So what vehicle are we talking about here?? Classic, P38 or L322??

What happens when you adjust the blower motor speed, do they react at all??

Go and check your pollen filters, sounds like they could be blocked up.

-Wills

P38 and I get no action on the fan whatsoever.....

I had a similar problem on my old L322, checked the fuse but that was OK, it turns out that it was the reastat.

Worth checking both of theses.

Sounds to me like your fan motor has no power getting to it.
You will get some air blowing through when you drive because of natural airflow passing through the heater matrix.
I had the same problem in my defender. I located the heater in the engine bay and checked and cleaned all the electrical connections along the wiring working back from the heater. It wasn't ling before i found a plug/connector which was corroded and green. A bit of a scrape and clean and power was restored.

Thanks guys I'll check on these. What is the Reastat?

A rheostat has a varying resistance across it when you turn it like a potentiometer but they are made to carry more current.

I thought the fan speed was controlled electronically. Do some models have manual control?