Involved in the degradation of long-chain fatty acids. a (3S)-3-hydroxyacyl-CoA + NAD(+) = a 3-oxoacyl-CoA + H(+) + NADH Lipid metabolism; fatty acid beta-oxidation. Repressed by FadR in the absence of LCFAs (fatty acids of 14-20 carbon atoms). When LCFAs are present in the medium, they are converted to long-chain acyl-CoAs, which antagonize FadR as to its binding to fadR boxes on target DNA and thus derepress transcription. Belongs to the 3-hydroxyacyl-CoA dehydrogenase family.