Hello Everyone,
I have a chevy blazer 2003 4.3 L V6 4door 4WD. I noticed a few weeks ago I had cold air blowing from the vents when the heat was on. as I drove to work I was watching the temp gauge it was at normal operating temp, just under 200 degrees and then began to rise up to about 230 then heat started coming from the vents and the temp dropped to normal. it went through this cycle several times as I drove to work. the first thing I thought to check was the coolant level witch brings me to problem #2, I can't get the hood open. I pull the lever I here a click but the hood will not pop when the lever is released. I had a coolant leak about 3-4 months ago I replaced the radiator, water pump and thermostat I have not had any visible coolant leak since. I only had that issue one time where it cycled through hot air and cold air otherwise it runs about 192 degrees. I am sorry if this post is somewhat premature but Since I can't even get the hood open to check the basics my imagination is running wild with spending lots of money and lost weekends spent under the hood of my truck. any help would be greatly appreciated

Chances are the latch is rusted and not releasing......

Have someone repeatedly pull on the lever, while with one hand you pull up lightly on the hood and with the other, use the palm of your hand to hit the top of the hood in the latch area....when it opens, lube the crap out of that latch......

Either two things....low on coolant(still have a leak somewhere), or your heater core is partially plugged.....feel the inlet and outlet hoses......if the inlet is much hotter, try reverse flushing the heater core....

on my hood, i pull the latch, then with a closed fist, smack it just above the latch, and it pops open.