I'm learning this stuff myself, so stand by for brighter minds, but AFAIK, the air dryer, if present, should be inline between the compressor's main discharge line and your wet tank (or the 'wet' portion of a combined tank). It's certainly possible you don't have one, either because it was never included in your original configuration, or was bypassed by a previous owner.
I don't have the experience to comment on the possibility of back-pressure from an air dryer causing compressor issues. But in regards to our air dryer - an AD-9 - I can't fathom how it could. The only way I see that happening is if the check valve at the output to the wet tank somehow came apart & components became lodged upstream. And if that somehow was to happen, you'd certainly have other brake-related failures.
My gut feel is that any compressor issues you may have are likely not related to anything downstream of the compressor. But again, I'm no expert.