Does smoking weed stop chlamydia antibiotics from working?

Weed. Long-term use can interfere with your immune system & make antibiotics work less effectively in future to prevent infection, but no direct interference between the two chemicals.
No. Smoking weed does not stop antibiotics from working, but it can and does interfere with your immune response. This means that although the antibiotics might effectively combat the chlamydia, your body may not do its internal cleanup operations (killing the rest of chlamydia, getting rid of their byproducts, etc) or protect you well from future infections.