The heater and a/c fan in my 2003 Trailblazer hasn't worked on speed 5 in a LONG time. IMO it's not really a necessity to have so it wasn't a priority. Here's how the fan speed controls work and how I tested the relay to know - not guess, know - it's bad.
Thanks for watching and stay tuned for the results of the clamp test.
If you live in Sussex County, Delaware and you're looking for a new shop you should come check me out. I mainly work on Chevy/GM vehicles but I'll look at anything. If you're interested, email me at may03lt at gmail dotcom. No way am I posting my phone number on youtube LOL