The blower motor speed resistor is burned out. That part is available from your local auto parts store.
Replacing the heater core in a 1993 Chevy 1500 pickup truck involves a moderate to high level of work. The process typically requires disconnecting the battery, draining the coolant, and removing the dashboard, which can be time-consuming. You'll also need to detach the heater hoses and possibly other components, such as the air conditioning unit, before installing the new heater core. Overall, expect several hours of labor, especially if you're doing it yourself.
Quite possibly the heater core is bad
The high beam fuse in a 1995 Chevy is located in the fuse box that is under the hood. The box is located on the driver's side fender wall.
Blower motor resistor defective
try replaceing the switch that controls the low to high for heater It's gonna be the blower motor resistor (near the blower motor).
My 1994 did the same thing.....the problem was in the high/low switch....
P1554 Cruise Engaged Circuit High Voltage
Most likely a failed blower resistor.
Replace the high speed relay.
The blower motor speed resistor is burned out.
In my experience Chevrolet 1500 4x4 dosent have a front wheel drive option. You should be able to drive in 2wd, 4wd high and 4wd low but no FWD.
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.