I just bought a used 1999 Honda Accord EX. Fan speed 1 to 3 don't work; only #4 works. Anything I have to do about this?

 

Have a volt meter

Testing is needed....ps, there is a way to get codes from the HVAC unit. I'd start with testing the blower transistor but that is me

 

Replace the blower motor resistor located in the duct work on the passenger side. I did that job last January (2016) on my wife's 2000 Accord. I got the relay off e-bay for less than 30 bucks. Pull yours first, and study the shape of it, so you can get the right one (e-bay had several that supposedly fit, but were different shaped). While it's out, you can test it too (I did and found it bad).