Tenant left behind a horrid marijuana odor in 1000 sq ft rental unit.

As far as the walls are concerned, which is best for removing (or blocking) marijuana odor? KILLZ or Zinsser stain-blocking primer?

UPDATE: 10/8/20 I don’t think airing out the unit would have done much even if the windows were left open for 30 days straight. Airing out the unit might have done if maybe the tenants were smoking in there for just a day. However, the tenants were in there, smoking weed, for 2 years. The scent had gotten into the walls.

Someone suggested that the walls didn’t need washing - stain-blocking primer alone would be enough. I gave it a shot and applied Zinsser stain-blocking primer to the walls. The marijuana odor was reduced by 70% in the rental. The scent was more in the walls than in the flooring because after shampooing the carpets, there wasn’t much of a change in the smell.

When I return to the rental in a few weeks, I’ll be very interested to see if the old marijuana odor will seep thru the primer (even a little) because it was never washed off before applying the primer...

As a few suggested, the ducts need cleaning, indeed! When I started the HVAC fan, I noticed the odor was still present... in the ducts!!! So, the ducts definitely cleaning. I’d say about 30% of the marijuana odor is still in the ducts.

If you’re facing the same problem, Zinsser (or KILLZ) is the way to go!

And how about, after spending about $120 on Zinsser from Home Depot, I found a 5-gallon tub of KILLZ in the storage closet outdoors, left behind by the previous owners of the rental! Wonderful...