Flush

I'm afraid to backflush it; the h/core might start to leak! I heard that one a long time ago about switching the hoses...could work?. I'll probably b/flush and take the chance. I think this car doesn't have the heater control valve. I didn't see anything spliced in either line that goes from the engine to the core at the firewall, and didn't see one mentioned in my cheapie shop manual. Thanks.