Xantia Blower Resistor Pack (Non-Aircon Type)

Unread post by **CitroJim** » 30 Mar 2010, 12:04

My Activa project is a non-aircon model and consequently has a resistor pack for blower speed control. None of these silly transistors

The blower was not working and this was found to be caused by the thermal fuse in the resistor pack going open circuit. Bridging the fuse brings full and perfect functionality.

I've never heard of one of these fuses going before. I wonder why it did

Two questions: Can it be replaced? If so with what and how? Would it be OK long-term to leave it bridged out given the blower is fed via a normal 30A fuse and the motor itself has a thermal cutout buried in the windings?

If the answer is No! and No-way! Anyone got a spare resistor pack they can donate to the cause?

spider · Unread post by **spider** » 30 Mar 2010, 14:07

Would have to assume overheating made it fail. It is rare but thermal fuses (you can see them inside power supply transformers sometimes too) can just decide to retire for no reason.

I'd have to suggest you obtain a replacement and solder it in (if its soldered) , tis there for a reason after all, although you probably would get away without it, overheating motor = potential cause of fire.

When a motor (a/c ones at least like your vacuum) are under more load (say the pipe was blocked) they actually use less current, I did not know this myself until it was demonstrated, the ammeter fell not rose.

Caution: The heat from soldering can cause them to 'fail' too. Use a shunt (pair of pliers if needed) to 'shunt' excess heat away.

Clogzz · Unread post by **Clogzz** » 30 Mar 2010, 14:42

Hi Jim,

The resistor pack can overheat from lack of airflow before the fuse and thermal cutout will know.
It’s also badly placed, and needs its own protection.
Thermal fuses also let go for no obvious reasons.

We have topics about that, and I’ll go digging.
The fuse is about 167ºC, available from Maplins and such.
It must be crimped in; not soldered because the solder will melt.

Keep enjoying all that fiddling.

Unread post by **CitroJim** » 30 Mar 2010, 14:56

Ahh, thats the baby Clogzz, missing it's little perforated tent...

How's that little tent held in? It seems to have no obvious fixing...

I noticed the fuse was crimped in. I ran the blower with the resistor pack out and by gosh, a heck of a draft rattles out of the hole where it lives to keep it all cool. Those resistor elements must dissipate a fair few watts.

The car in question has had long-standing scuttle leaks and all has been very, very wet in the past. I wondered if that had any bearing. Still, with the blower rigged to work, I has happy to find the heater matrix is OK.

Thanks Andy, from a safety point of view it will most certainly be replaced... I'd not fully considered the implications of a fire resulting from a failure and even those resistor elements are little electric fires in their own right and if the fan stops, goodnight Vienna. Toasted Activa is not good...