Blower motor resistor values

[Peter Orban]

Hi Chris,

Don't just measure continuity from the switch to the blower connector with the DMM, but turn on the ignition, the fan at various speeds, and see if you get the 12V at the blower connector. The brown wire is the ground, one of the other three wires will provide the 12V according to the speed setting. Check all three speeds.
I am doing the same on my '88 Jetta, the blower resistor looks pretty much the same:
The resistance values are 4 Ohm, and a tap at 3 Ohm (or 1 Ohm, haven't looked which way is it wired up).
This is a picture of the audi resistor: <http://img.wpac.com/live/R203218028OEA.JPG>, and this is the picture of the VW resistor: <http://img.wpac.com/live/R203226416AFT.JPG>
I do not see the resistor ever going, everything else in the fan assembly will burn/melt sooner when the fan seizes. What usually fails first is the thermal fuse, that little red tipped component on the left side of the audi resistor picture. However, that affects all three speeds!
You can get a thermal fuse (10A, 130C) even at Radio Shack, around C$5.00 here in Canada, or cheaper at an electronic component store. These are widely used in small appliances, like toasters, oscillating fans, etc.
When the fan brushes make good contact, the blower motor resistance is about 0.6 Ohm. So with the resistor pack hooked up you should measure 0.6 Ohm, 1.6 Ohm, 4.6 Ohm on the motor connector.

Good luck, Peter


Message: 4
Date: Mon, 24 Oct 2011 17:11:44 +0000
From: CHRIS PERRY <cgperry42 at msn.com>
To: <quattro at audifans.com>
Subject: RE: Blower motor resistor values
Message-ID: <SNT133-W59A8422C2A4BCBAEDB7354ABEF0 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"


Steve, Al and Huw, 
Thanks for the replies.  I had replaced the blower motor and heater core and was hoping that the new blower motor would fix the issue of only running on the highest two speeds. Alas, that was not the case.  I used my DMM to check continuity on the switch as well as the wiring harness to the resister and they both checked out good.  By process of elimination the resistor seems to be bad.  I found one locally for 45.00 ( about 15.00 more than online) but at least I'll have it today.
 
Chris Perry