2000 Malibu...NO HEAT....need help

My 2000 Malibu has no heat. I start it up,let it run. The temp gauge climbs quite high and finally drops down to normal. I turn on the heater and only cold air blows. Since the temp gauge does drop back down to normal I assume the thermostat is ok. My question is is there a way to check the heater core myself to see if it's clogged or is there something else to look for? And if the core needs replacing is it a pretty difficult job?Also my fan only blows on high which I suspect is the blower resistor that would be a entirely differant issue wouldn't it? I appreciate any help and insights on this. Not real smart with cars and I live in the North east..........could use a little heat....Thanks

Check your coolant level... If its low, might be a leak, so find the leak, fix it, and add some water/coolant. My malibu was leaking coolant from the upper radiator hose, and when the coolant would get low, the heater would not work, and the temp would also shoot up quick and then drop back down after the fans kicked on...so give it a quick look.

you nailed it knowlegeable1. Thanks so much man.I guess the low level coolant light isn't working. I really appreciate your input.

No problem... Thats what we're here for. Glad i could help.