What was the specified fuse size? If it was 5 amps and now it is
blowing 5 amp fuses, then there is something wrong down stream from the

fuses. Hard to tell from here what that might be. What all runs off
that
fuse? Does it include some sort of motor. Maybe that motor is drawing
more
current than it should.



The 5 amp fuse should be 3 or 5 amp, depending om model. It is an
automotive type fuse and protects the low voltage circuit, including
the transformer. If the fuse blows you have a short in the low voltage
circuit. The other possibility is if the contactor has rust or dirt on
the armature. That will cause the contactor coil to draw high amps
just like a motor that is just starting. If the reversing valve coil
fell off the reversing valve, it would do the same thing. The stuff on
the contactor armature (pole pieces) is called swarf.

Stretxh