E30 Zone

Next up on my list of jobs to do is the rear cabriolet heater blower. The switch lights up but the rear blower doesn’t neem to want to blow. Any ideas on troubleshooting?

I reckon the blower relay and switch both get fed from fuse 8 - so if the switch lights the fuse is good - I'd pull the rear seat back out and check power at the relay first - could be duff.

Paul

paultv wrote: ↑

Mon Dec 02, 2019 4:13 pm

I reckon the blower relay and switch both get fed from fuse 8 - so if the switch lights the fuse is good - I'd pull the rear seat back out and check power at the relay first - could be duff.

Paul

Cheers Paul. I’ll take a look at the relay power.

It appears I may be wrong - fuse 8 feeds the relay at the rear and energises the relay via the dash switch - however the yellow dash switch lamp gets
power from fuse 23 via the main light switch - you have a light so 23 is OK.

So, first supect is fuse 8.

Then check pin 8 ( 86 Black ) of the rear relay for consstant 12v when ignition is ON.
Then check pin 6 ( 30 green /blue ) of relay for 12v when the heater/blower switch is ON - whilst ignition is also ON.

You may also want to check that the "top down" switch is working both electrically and physically. If it is failing to make a connection with the roof UP it will think the roof is down
which stops the relay energising coil from making its path to the body of the car - this will "switch off" the blower.

With everything switched OFF and the roof up you should have a dead short 0 ohms between the relay pin 4 ( 85 ) brown/black wire and the car body.

If pin 2 ( 87 Black/red } has 12v when the dash switch is operated and the relay clicks I would suspect an internal problem with the blower and if fuse 8 blows when you run the blower
for a short time it indicates a shorted or damaged heater coil which causes high current flow to blow the fuse - also true if the motor is seized up then the heater coils become too hot
and the fuse pops or the internal thermal fuse gives way - resulting in running motor but no heat.

Paul

paultv wrote: ↑

Tue Dec 03, 2019 10:47 am

It appears I may be wrong - fuse 8 feeds the relay at the rear and energises the relay via the dash switch - however the yellow dash switch lamp gets
power from fuse 23 via the main light switch - you have a light so 23 is OK.

So, first supect is fuse 8.

Then check pin 8 ( 86 Black ) of the rear relay for consstant 12v when ignition is ON.
Then check pin 6 ( 30 green /blue ) of relay for 12v when the heater/blower switch is ON - whilst ignition is also ON.

You may also want to check that the "top down" switch is working both electrically and physically. If it is failing to make a connection with the roof UP it will think the roof is down
which stops the relay energising coil from making its path to the body of the car - this will "switch off" the blower.

With everything switched OFF and the roof up you should have a dead short 0 ohms between the relay pin 4 ( 85 ) brown/black wire and the car body.

If pin 2 ( 87 Black/red } has 12v when the dash switch is operated and the relay clicks I would suspect an internal problem with the blower and if fuse 8 blows when you run the blower
for a short time it indicates a shorted or damaged heater coil which causes high current flow to blow the fuse - also true if the motor is seized up then the heater coils become too hot
and the fuse pops.

Paul

Amazing info and direction, Paul. Many thanks!