Sounds like you have the same problem I had only weeks ago. My heater blower only worked on the 3rd setting(resistor pack behind the lil grills on top of the bonnet burnt out)
Then my blower would make a very loud chopper type sound when on the 3rd setting.
Changed the resistor pack without too much grief, I say too much as the other option was the whole dash AND centre console out to get to the heater unit which I believe has air con attached to it whic I was very very wary of tampering with.
So I'd say if your replacing your resistor pack then don't fret too much as it's just a fiddly tight arm scraping skin off kinda job
It sounds like you have the same set up as me, air con blowers should be in the passenger foot well area ( under the dash visible if you stick your head down and look up)
Above that inside the dash , you can't see it unless you take the centre vents all off, disconnect the clock and electric mirror switch.
The air con unit lies in there with the fans directly below it so it blows out the centre vents.
Here's the resistor replacement you want, it's a good set up.
Accessories Catalogue - Britpart - The Quality Parts for Land Rovers
Although it says britpart it's made by British Atlantic in the USA and is a good quality replacement as you can't get the original ones anymore