2005 suburban 1500 2wd base model:

Wiring to resistor fried a year ago, spliced and replaced, no issues. A week ago the connection from the resistor to the motor fried. Replaced the resistor and blower motor and it worked fine. I'm now smelling a faint odor of burning electrical and I can hear the squirrel cage making a clicking sound that is directly related to the speed at which the a/c is set. If it weren't for the slight burning smell I might think there was debris stuck in the blower. But if that were the case I shouldn't be smelling any burning, which leads me to the main question: Assuming the blower motor/resistor aren't defective, what would be causing these electrical issues? Is there too much juice going in and causing overheating? If so, what's the fix? Incidentally, we've been having a number of electrical issues (speedometer inoperable, oil pressure gauge registering way over the max line, occasional dash lights fade out/turn off entirely). Might this be due to a bad engine ground? If not, then what? Thanks for any advice. Hope we don't burn up in this thing...