How difficult is it to change heater cores in my blazer?

I have a 1999 blazer and it is not heating properly. Today i went out driving and came back home and the hoses going to the heater were not even hot. So i assume the heater core is plugged up or not working. Is there any way to unplug it without taking it out? And also how hard will it be to take out and replace if i have to? I am assuming it is behind the dash because the hoses go through the firewall.How difficult is it to change heater cores in my blazer?first of all it could be be many things ,thermostat thats usually the cause so start there sometimes it will stick open , or it could be low on water yes i know sounds stupid but 6 out of 10 times someone brings there car in thats what it is or the radiator is plugged that's easy to see just take the bottom hose loose if water comes out steady it is not plugged iv never seen heater core plug in 15 years it will bust or go out then it will put antifreeze on your windshield when you turn on the defrost. the heater core does not heat the water it just sits in front of the fan with the hot water the moter heats the water when the thermostat closed water gets hot it opens the water is moving so it stays cool plus if its pluged it will get real hot like a plugged thermostat the core is not pluggedHow difficult is it to change heater cores in my blazer?If you live in a state like me and never use heat, you can take the two hoses off where they go through the firewall and go to autozone and get an adapter to hook them together. As far as changing out the heater core, half the dash has to come out and if you never have done this, I would pay a shop to do.How difficult is it to change heater cores in my blazer?take off coolant hoses in engine compartment and put a water hose to it..or ....remove dash.. be sure what problem is...is hot water going into core????... i had same symtoms and it was little door that moves heat around....25 dollarsHow difficult is it to change heater cores in my blazer?you should try taking the line off, and flushing the pipes of the heater core out first. probably just clogged with debris. then reconnect the hoses and try the heat, that should do the trick. on those you gotta remove the whole dash carrier and evaporater box to gain acces to the core. try flushing first. pretty much if its not leaking into the car or anywhere else, its just clogged.How difficult is it to change heater cores in my blazer?It is behind the dash and its more time consuming than difficult. What I would recommend first is disconnecting the hoses from the engine and try blowing through them or running a garden hose through them to see for sure if that's the problem. It won't take very long and will definitely prove if the problem is in the core or elsewhere.How difficult is it to change heater cores in my blazer?If neither hose is hot, look at the thermostat as being the problem. Usually one hose will be hot and the other will be cool or just warm if the core is plugged. Pay for a proper diagnosis before you start buying parts.