Heater Blower Motor Fuse Blowing

**doctor_P** · 06-12-2010,11:01 AM

The 30A fuse on the heater blower motor circuit in my Passat blows intermittently.
The vehicle has a climatronic AC control module. It seems that when the unit is in AUTO the fan will operate but then the fuse will blow. When I put the climatronic into MANUAL and keep the fan speed at a medium speed the fan keeps operating.
Having looked at the circuit and at various discussions on heater blower motors I am coming the the view that the problem may be the blower motor resistor unit.
Before I go off to the scrappy I'm wondering if anyone else has had similar symptoms and found a fix.

**martin1810** · 06-12-2010,02:15 PM

Blowing the 30A fuse suggests the blower motor has had it.

**doctor_P** · 06-12-2010,11:49 PM

The motor is fine - it works when connected directly to a 12v supply and is currently working when the climatronic unit is in MANUAL. If I put the climatronic in AUTO the fuse blows - not immediately - but at some operating point which I haven't yet identified. My thinking is that as it switches the resistors in/out there's a short causing the fuse to blow. I'm wondering if anyone else has had the problem and fixed it with a resistor unit replacement.

**martin1810** · 07-12-2010,09:59 AM

I think you are correct. The resistor comes out the bottom of the fan housing so take it out and test the resistance. In my experience motor comutator/brush problems usually cause the current to spike and blow the fuse, but a shorted resistor pack would do the same thing.

**doctor_P** · 07-12-2010,05:33 PM

Thanks for the reply. The unit on my car is separate from the fan and is mounted on the bulkhead with a big heat sink on the back of it (VW Part No 1JO 907521). I'm off to the scrap yard once the snow melts to see if I can scavenge a replacement. I think I'll get a big box of fuses as well. I'll post a report on the results.

**doctor_P** · 14-02-2011,11:40 AM

Well the snow finally melted and I got down to the scrap yard and luckily obtained
a resistor unit - (£5 rather than £80 from a dealer). Put it in and after about 5 minutes the fuse blew again. After much cursing and perusing of my Haynes Manual (ISBN 1 85960 917 1) I noticed that Diagram 11 also includes a feed from fuse 25 to the air compressor clutch and the A/C cutoff module. I had just been looking at Diagram 10 which I thought was the full story regarding fuse 25.

So I've isolated the supply to the air compressor clutch - the fuse no longer blows.
One problem sorted another found. Ho-hum.

**aimcn** · 25-10-2012,02:19 PM

Re: Heater Blower Motor Fuse Blowing
I taught i was the only person in the world with this problem. like your problem my 30amp fuse keeps blowing any time i turn up speed of the climatronic heater. i also changed the resistor/capacitor. can you tell me how you isolated the supply to air compressor please, this would be my 3rd winter without heater fan. DAMN CONDENSATION!!!

I know this is a year later but if you or anyone who knows this problem see's this pleeeeeeeeeeeeease reply with solution...many thanks

**doctor_P** · 25-10-2012,05:59 PM

Originally Posted by aimcn

Re: Heater Blower Motor Fuse Blowing

I taught i was the only person in the world with this problem. like your problem my 30amp fuse keeps blowing any time i turn up speed of the climatronic heater. i also changed the resistor/capacitor. can you tell me how you isolated the supply to air compressor please, this would be my 3rd winter without heater fan. DAMN CONDENSATION!!!

I know this is a year later but if you or anyone who knows this problem see's this pleeeeeeeeeeeeease reply with solution...many thanks

There's a connector to the clutch unit in the engine bay. I can't remember if you have to take the compartment cover off from underneath to get at it. Unclipping it sorted the blower fan fuse problem. (I refitted a replacement aircon compressor it wasn't too successful but that's a completely different matter). My blower fan is still working.

**Crasher** · 25-10-2012,06:02 PM

Which fuse number keeps blowing, number 5?

**doctor_P** · 25-10-2012,07:50 PM

Originally Posted by Crasher

Which fuse number keeps blowing, number 5?

It was Fuse 25 in diagram 10 (Heater Blower etc) in my Haynes Manual. However, as noted, this fuse also appears in diagram 11 (Air Con). Diag 10 doesn't show this hence it took me some time and £5 for a replacement resistor unit from the scrappy before I sorted the problem.

JP