i tried to charge the ac but the low side pressure only reaches about 10 lbs, when it should be about 25, a shop told me i may have a clog somewhere in one of the lines, well i check out all the lines, and there all good, but when i got to the evaporator box, the low side fat line i couldn't blow threw it at all, i put compressed air to it and still wasn't getting threw, so is it suppose to be that way or is it really clogged, need response quick, my daughter can ride in my car untill i get it fixed, its too hot, thanks