our shop services jag/mb/bmw/porsche and we have the specific
diagnostic software for these vehicles. we cannot diagnose
toyotas or chevys or hondas. your blower issue could be in the
relay, blower speed controller or the climate control module.
you can diagnose this by just swapping new parts, but that is very expensive guesswork. an experienced tech could go in piece by piece to check voltage and continuity, but that is very time consuming. or you could access the system and find out what trouble codes are present with the correct software.
once the codes are identified, they can give you an estimate.
but one thing is certain: the shop will need the correct software to diagnose this problem if you want it fixed.