1994 Subaru sambar van kv3, automatic, carbureted, AC, 43k kms Have an issue where the heater fuse keeps blowing. This is actually the blower motor fuse, no. 17 on the fuse block. Blower motor works on every power setting with no issues, when the AC button is pressed the compressor kicks on and blows cold air, this will work for about 5 minutes at idle then the fuse blows, if you give the van any gas it blows the fuse instantly. This only happens with the AC on. No short found anywhere in blower motor circuit wiring Blower motor tested Blower motor resistor tested Blower motor fan speed switch tested Everything checks out The blower motor and AC circuits are generally not connected, although I've found the blower motor circuit is connected to one of the 3 AC relays behind the glove box, all 3 relays tested and work. Checked all wiring in the AC circuit AC compressor spins free, clutch works AC system charged to correct psi Low and high side pressure switches tested I've traced every wire on the blower motor circuit since the English wiring diagram is terrible, and can't figure out where the increased load is coming from. I've seen this exact issue described on this forum but there's never been a solution. Trying to provide as much info as possible, I'm at a loss Any help appreciated
Blower motor tested how? What's normal current draw? Too much current being drawn in the circuit. Most DMMs/VOMs should have the capacity to read the amperes while being in series with the blower motor. Could be caused by one or more overheated /shorted turns in the motor or excess drag on the rotor from worn commutator brushes, dry or worn out bearings.
I tested the resistance of the motor, along with bench testing on a battery, motor works fine and honestly looks new just like everything else in the van due to the low mileage. Also ruled out the blower motor since the it will blow air on every power setting all day long with no issues, right up until you press the AC button, then the fuse blows. The owner stated the fan quit working after driving down a bumpy road, first thought is loose connection or short, can't find any wiring issue, never heard of an AC circuit somehow adding an extra load to an blower motor circuit, without a proper wiring diagram I'm back to checking every wire.
What is the current draw of the A/C clutch? With the fan out of the circuit, does the fuse still blow?
My guess is the clutch on the compressor as well. It is electromagnetic, so that seems like most likely suspect here.
