I have had a sinus infection for over a year now. It is accompanied by a foul odor and green phlegm. Is this normal for a sinus problem? No fever.

Chronic sinusitis . The symptoms you describe are suggestive of a chronic sinus infection. Treatment with a longer course of a strong antibiotic like Augmentin (amoxicillin and clavulanate) can help most cases. You may need a sinus imaging study to further evaluate this.
See below. Most sinusitis will resolve without any specific treatment. Topical (neosynephrine) or oral (pseudephedrin) decongestants and saline nasal sprays give symptomatic relief. For severe or intractable infections antibiotic treatment is indicated. Your infection for 1 year is much too long. I would recommend a sinus culture, appropriate antibiotic treatment and evaluation for allergic sinusitis.