Should I mention my interest in teaching in SOP and recommendation letter? I'm currently thinking of applying to PhD in Economics, after much consideration and reading through answers in my previous question: Should I do master or phd to teach in community college. 

Basically, I'm interested in teaching in post-secondary level, and I have little interest in doing research (though I'm currently doing full-time in a research institution). However, PhD is recommended to teach in post-secondary level in most institutions, at least in United States. 

As I'm thinking of preparing for Statement of Purpose, I'm conflicted as how I should mention my passion in teaching, since SOP is meant to show research interest. Should I not mention anything about my desire to teach? If I do mention, should I mention that I'd like to teach rather than do research upon completion of PhD? How do admission view applicants who are more interested in teaching?

Similarly, I'm unsure of how I should talk to my professors who agreed to write recommendation letter about my deviation from being an enthusiastic researcher. I have two professors from undergraduate that I'm close with, but they only know that I used to be very interested in research when I was in college, and they do not know that I have lost much interest in research after graduating and working in a research institution. Should I let them know that my interest has changed? How about my current research advisor, from whom I'm thinking of asking for my third recommendation? Should I let him know as well?
For a SOP, you may mention something about your desire to teach. However, I think at most higher-ranking economics departments, this would not be viewed as positively as having a strong research interest and agenda. You may gain a small benefit if the reader of the SOP gets the sense that you are a "team player" who will do a good job TAing and not make a fuss about it. 

(I will note here that my advisor has told me that some faculty are extra  suspicious about investing effort when they hear too much discussion of teaching from a woman - they already think of women as being less serious about research because of biases and discussion of teaching by a woman can support their stereotypes. So note this if you are a woman.)

I would say that it is not inappropriate to talk to your recommenders about your desire to teach economics. However, I would tend to frame it as and interest IN ADDITION TO research. You can say, I really see myself ending up at an institution that combines teaching with research - what would you recommend I do at this point to make myself the most competitive for those types of places?