Fuse #20 keeps blowing

[Chanceton14]

I've messed around on the car today trying to figure out the issue. First I just tried just putting a new fuse in with a.c. and blower on and it blew immediately. Next I took out the blower motor and cleaned it with sea foam, (the fans moved freely by hand) then hooked it back up and the blower ran for about 10 seconds before it blew the fuse again with the a.c. on. Next I took the blower out again with a.c. on and it didn't blow a fuse. Then I hooked the blower back up with a.c. off and blower on and it ran for a minute but the blower was making a loud grinding noise and work at speed 4. The snow flake and the recirculation button doesn't light up in any of these test. What do I need to check next? I didn't think it was the blower motor since it moved freely by hand, but I think there is a good chance it is the blower motor anyway. A.c. compressor seems to be working, the belt is turning. Any ideas on what to do next? Thanks for the input
car is a 87 325 with a s52 swap( blower motor is a *itch to get out).

[Tom D]

the blower's motor has a short in either the stator or the rotor.

[Chanceton14]

the blower's motor has a short in either the stator or the rotor.

Put a new blower motor in today..blew the fuse and popped the hot conector off the motor. And my window switch seems abnormally hot. What you think? Thanks

[Tom D]

what circuit does fuse 20 handle? obviously the blower, but what else?

the window switch getting hot could be high resistance in its circuit, or a short to ground.

do I have this right?

old blower
* blower and AC on - fuse blows
* AC on, blower off - fuse ok
* AC off, blower on - fuse ok, fan works high speed only, fan makes noise.

new blower
* blower and AC on - fuse blows
* AC on, blower off - ?
* AC off, blower on - ?

even without knowing the answers to the last two scenarios, I'm going to summarize that you have the blower wired wrong. especially since you have a swapped engine.

[drewyoda]

Hey guys, what came of this? I'm having the a similar problem, but my fuse 20 is melting instead of blowing. The aux fan resistor was changed after the fan was found to be jammed by debris. For me, we can run the blower all day as long as the AC is off. If the AC is on for an extended period, that circuit gets so hot that it melts the fuse.

[thejlevie]

Your HVAC fan motor could be bad. My project car had the same problem and a new blower fixed it. It was pretty obvious that the blower was the problem as there was the smell of burning paper when the fan was on high. However in your case you also have some problem in the A/C system other than the blower. The other high current device is the compressor clutch. But a high resistance short in the A/C wiring is a possibility