Truck Repair: Fuse blowing on A/C Heater, pickup 4x4, blower motor

Question
I have a 88' Chevy 2500 Pickup 4x4. My problem is: When I put vehicle in 4 wheel drive the fuse for the heater control and 4wheel drive blows out. It only happens when 4 wheel drive is engaged. When fuse is changed it will stay on for about 5 minutes or less and then blow again. I need four wheel drive for snow plowing so keeping in 2 wheel is not an option.Any help would be great, thanks

Answer
Hello Anthony,
Apparently, the 4X4 works now then?
I would say either the actuator on the front axle is drawing too much power, or the blower motor is.
Have you tried with the blower on a low speed?
I realize it isn't recommended, but have you tried the next larger size fuse?
I don't know exactly what the resistance through the axle actuator should be, but I will send a link for some aftermarket axle engagement systems, and one has some troubleshooting tips.

www.4x4posi-lok.com/PDFs/troubleshootguide.pdf

offroadltd.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=ORL&Product_Code=PSL600

www.4x4posi-lok.com/

Could also split them from the same fuse, but one of them, or a switch, is drawing too much power.
Good luck,
Van