Maybe electrical problems
 

I have a 2003 Trailblazer LS with 128,000 miles on it. The first problem is the gauges, non of them work except the fuel gauge. The oil pressure is stuck all the way over. The digital part of it only works sometimes. Is this a ground problem or wiring? Could it be the cluster?

Next is the when i turn on the heat controls, nothing happens. No clicking or anything. It is completely dead. Could this be related?

I have not noticed any other issues yet.

not related.

the cluster stepper motors and led's are notoriously bad. they can be repaired through the dealer, shops on ebay, etc. or replaced yourself if you so inclined.

for the blower motor; check fuses, check for power and grd to the blower motor. If you have power and grd at the motor...hammer fist the motor...if it starts to work, the motors brushes are worn. typically when the blower resistors go bad you will still have 1 working speed.