There is a resistor/ circuit board near the heater motor that need to be replaced. You can get one from almost any auto parts store.
With no speeds at all, check the fuse, then check the blower speed switch and it's electrical plug.
Only for the high speed blower function. The lower speeds go thru the blower motor speed resister.
The blower speed switch on the dash and the plastic electrical plug that plugs into it may have melted down.
I have a 1999 Chevy Suburban LT and if I stay at the recommended hwy speed I easily get 19mpg
The high speed relay for the blower motor would be found under the hood, on the passenger side of the firewall, close to the blower motor speed resistor.
It could be the high speed heater motor relay is stuck on or the switch itself is broken.
It is located on the left rear of transfer case.
If you have no speeds at all, including high speed and you have power at the fuse and the fuse is good, I would suspect the heater blower speed switch and or the electrical plug to the switch is cooked. If you have high speed only and the rest are dead, I would suspect the blower motor speed resistor.
Most likely, 355.
Yes there is, but it only operates the high speed function.
Switch problem? Cables disconnected?
It has a bad "Blower Motor Resistor" The fan switch itself is fine.