Well, kind of sort of. No filter manufactures will recommend blowing air into them. Well, no good filter companies will. You circumvent the pre filter that way, blowing dirt into your carbon and reducing the life of your filter.
I suppose I could try blowing through. Would only take a couple minutes to switch the fans around. However, I think it's going to be the same result. At least on paper. Air is currently getting sucked into my room, when I zip the panda closed it wants to pull of the wall. My thought is that the air coming into the room is allowing the air (and co2) to get sucked out.
If I reversed the fans, I would think the opposite would hold true..the co2 would get pushed out, not pulled out. Honesty I live AC hoods but they are a huge PIA for bigger grows. Just bought 18 ballasts for a bare bulb room. Hang ballasts, hang cord and bulb; done!