RV Repair: No water in RV from City line, hot water tank, water plug

Question
2009 Viewfinder by Cruiser RV: We had water running in the Trailer after we drained the antifreeze (Hooked up to City water),however before putting in the hot water plug we ran water through the hot water tank turning the valve in the trailer on and off. Well doing so we heard a pop. Now no water will go into the trailer well hooked up to the City inlet. We have checked the Check valve (new one installed) on the City inlet. but still no water. Pump work fine with the water in the tank. On our RV it has 2 inlets - one for city water and one for the water tank they are not joined by the same hose.Still no water will come out of any faucets well hooked up to city water.We have checked the 3 valves under the bed and they are turned on. Could there be Air in the system that is stopping the water from coming through the pipes. We have never had any problem with it before. Any help you can give would be appreciated as Cruiser RV is hard to get help from And we would like to try and save as much money doing a repair ourself unless we really have to find someone to repair it.
Thank you
Linda T

Answer
Do you have access to a compressor?  If so, I think you have an obstruction in the city water line.  That pop you heard was the old check valve comming apart.  A piece probably went forward and plugged your line.  I would remove your new check valve, and disconnect at the sink...somewhere where you won't be able to go toward the pump water.  I would blow air from a compressor from the sink toward the new check valve.  This would blow out your lines.  I also would not hurt to blow behind the check valve toward the hose hook up outside the RV.  


Good Luck