1997 Avensis AC heater fan not working

[220K Avensis]

Hi all,

New to the forum, despite me owning my Avensis for 18 years.(I love it that's why I have never sold it).

I have never had any problems with the car until now. (apart from a clutch at 186K miles).

My heater AC fan has stopped working. It was a bit intermittant for a while but has now totally packed in. I removed the fan and tested it on the bench.

It works fine.

I have measured the voltage at the connector that plugs into the fan. When you switch the AC on, you get just over 10V, and little increments down as you select the slower fan speeds. So it is as to be expected. The relay is working as you can hear it change over when the AC is switched on, as I say, you get voltage at the connector.

But here's the thing. When I connect the fan assembly back in, no volts, and the relay is kicking in. So why has the voltage been slugged when the fan is switched in?

Is there a poly switch (thermal fuse) somewhere?

Any pointers greatfully received.

Jeff