I have recently read the codes that my blazer has put off and I got #62- Engine Oil Temperature Sensor, High temperature indicated..Does this mean that my thermostat isnt opening up at the temperature it should be? Im already running 10w-40 and thought about running 20w-50 but im not sure yet..it there anything that yall would think could help this? or could it be as simple as replacing my sensor?

Also the other code that was put out was #61- A/C system performance, or degrading oxygen sensor. I have been having some problems with my A/C, the light on the A/C panel is blinking. I did the whole battery thing and it worked but now its starting back up again, to where its only blowing out air, its not cold at all..I checked my freon level and it said that it was overcharged but im not sure its saying that because my compressor or clutch wasnt kicking on. Would disconnecting my battery to get my clutch and compressor to kick on and then test my freon that way, cause I think its giving me an overcharged reading because of all the pressure thats at the top.

Now I dont have a code for this one, but as I was rolling up my windows at the same time I noticed that my RPM gauge was shooting back and forth from 0 to 80 and my battery gauge was going crazy too! does anyone know what could be the problem?