Quote:
Originally Posted by HPsauce
I just can't think that it's the actual motor, if that was the problem it would have been getting worse and worse over the last year. And the fact that fiddling with wiring made it work after the initial problem.....  |
Agreed. You'd expect if it's something like worn brushes that the fault would get gradually more frequent. Although I suppose it could be caused by a broken internal motor connection that is making/breaking due to thermal expansion or vibration.
Looking at the circuit diagram (is this the right one?) ...
It looks like E87 is the HVAC control unit in the dash, and J126 is the 'hedgehog' (and V2 is the blower motor of course). Is that right?
Hedgehog (J126) on the left in this illustration (I assume):
J126 looks like a very simple motor speed controller, possibly as simple as a single power transistor because it appears to have no positive supply, which would be required if it contained anything more complicated. The circuit diagram implies that it merely controls the current between earth (43) and the motor's negative terminal (L9). Since it probably gets hot when dissipating power (as the large 'hedgehog' heatsink also suggests) and repeatedly cycles between hot and cold throughout its life, I would imagine there's a good chance it's prone to developing 'dry joints' internally.
The fault could also be on the motor's positive feed side of course, such as a simple bad connection somewhere.
I think I'd still be inclined to attach a couple of wires to the motor terminals (assuming they're not too difficult to get to) but, rather than connect an LED/multimeter between them, connect them instead to a supply and ground connection. In other words, an LED/meter between the motor's positive feed and ground and an LED/meter between the motor's negative feed and 12 volts. Depending on which one disappears when the fault occurs (or none if it's the motor), that should give a good indication as to where the fault lies.