Jeff Conaway's Cause of Death -- Heart Problems, Pneumonia

Jeff Conaway died from multiple causes, from Aortic valve problems to pneumonia ... this according to the L.A. County Coroner. And, the Coroner says, his death at 60 was an accident.

Among the causes

-- Septic Emboli ... an infected arterial blockage
-- Aortic Valve Endocarditis ... heart valve infection
-- Coronary Artery Disease
-- Pneumonia
-- Encephalopathy ... brain disorder resulting from drug overdoses