Starting problems with good battery and alternator
 

2000 chevy blazer wont turn over. makes clicking noise as if battery is dead, dim lights, slow power windows, and weak horn. but battery is not dead when it was checked with voltmeter. both alternator and battery replaced a year and a half ago. little to no corrosion on battery and appears to have good connection. yesterday driving fine and battery light came on next starting attempt it wouldnt turn over. any suggestions

In conjunction with the dim lights and slow power windows I'd say that battery needs to be charged. Did you try starting it with a booster or a jump vehicle to see if it helped? Get that resolved before moving on to the charging system.