2001 express van blowing heater fuse

My van has been blowing the heater fuse. I took it to a shop and they repalced the resistor. it blew the fuse about an hour after i left the shop. took it back in and they replaced the motor for the fan and again shortly after i left the shop it blew again. i havent notice if it blows if you hit bumps or if you change the speed of the fan i have spent over 500 bucks in shop bills and parts to still have no heat can someone please help and i live in canada so you know i need my heat

Is the fuse that blows underhood-(60 amp- I doubt it's this one) or inside (20 amp) the van? If inside the van- then the likely hood of a bad blower is less-- does it blow only on one of the lower speeds? or is it always on high speed fan when it blows- or does it matter? These are big hints in that there are separate fuses, and circuits that can be looked at. The control head may be the culprit if the inside fuse is the one that always blows.

Also, notice the "mode" that you are in when it blows, that same circuit feeds the a/c relay- so there could be a problem with it, or the wiring to it- but it would only blow when in defrost, mix/blend, bi-level, or a/c, or max a/c mode- if it blows in floor or vent modes- this would rule out the a/c circuit.

As far as electrical components go- there is only one more to change- and that is the control head in the dash. As always a good shop with proper diagnosis could have done more to eliminate installing the wrong parts- like fusing the blower separately to prove or disprove it was bad- the resistor could easily have been tested first- etc..

As always there is a chance of chaffed wires somewhere- but usually highly unlikely- unless someone has been in there recently- adding in aftermarket stuff, like remote starters, different radios, etc-- heck someone could have even put something else on that circuit- like a seat heater, or inverter or something- may not even have anything to do with the blower motor. You are the only one who can answer these questions.

thanks for the fast reply. i dont have a/c and there is no aftermarket stuff in my van it is blowing the fuse inside and we have sat there with a new fuse in with the fan blowing changing the speed ,temp, and position of where it is blowing but could not get the fuse to blow it doesnt seem to be blowing with any certain thing we did.