2006 Avalon Limited Blower Motor Relay Location

[tanner520]

Hi All,
I just found this forum and I'm hoping it will help.

I'm good mechanically, electrically, etc., etc., so I thought I had this one beaten......but no.

My wife's 2006 Avalon Limited has automatic air and yesterday she said the fan intermittently stops blowing (and it's 110 degrees outside in the Dallas area). So, I've fixed the AC on all my cars and this sounded easy....blower motor relay (or resistor, if you like) and I get one at O'Reilly (and the relays are cheap too).

I looked for the air box under the hood by the firewall...nope, couldn't find the relay.
I looked in the relay box under the hood...nope, couldn't find the relay.
I looked under the dash on the driver's side...nope, couldn't find the relay.
I looked under the dash on the passenger's side after taking the glove box out and looking all around the blower motor...nope, couldn't find the relay.

Where is this darn thing??? I thought I read somewhere that Avalons with auto air might not even have a relay. Is that true??

I even bought an online subscription to eAutoRepair.net to look through the diagrams for the Avalon Limited.....no luck and maybe wasted $13.

Does the Avalon Limited have a blower motor relay / resistor for the fan motor or did I just waste my money on a relay at O'Reilly ($17) plus my online subscription to eAutoRepair.net ($13) ?? Or is there a totally different diagnosis to this problem altogether??

Thanks for the help,

Signed - Flustered in 110 degrees in Dallas

[inov8]

I have the 2005 shop manual and expect the 2006 model is identical. There is no dedicated blower relay, nor is there a resistor-set to reduce the speed. Like many manufacturers today, Toyota uses a power transistor that is turned on and off at a variable interval (called Pulse Width Modulation, or PWM for short) for speed control. While the combination of a relay and power resistor would cost them about ~$1.50 total, the power transistor costs only ~$0.50 and provides the advantage of more than 15 blower speeds instead of just 3 or 4

From what I can deduce from the wiring diagram, the power transistor appears to be located within the blower motor assembly (located behind the glove box).

[tanner520]

Any pictures, diagrams, procedures, etc., etc. would definitely be helpful. I've never seen anything like that.

Thanks.

[inov8]

PWM blower motor control is not new, Motorola was building them for GM when I worked there 25 years ago. It will generally be found on vehicles with fully automatic climate controls (just set the desired temperature), Customers would not be pleased with the incessant clicking if they used relays to automatically adjust the blower speed.

The Avalon blower motor connector has 3 wires:
White - this goes directly to battery (+12V) via a 50A fuse labeled "heater".
White with black stripe - Ground
Red - speed command input from the climate control computer.

3 bolts on the bottom retain the blower assembly to the plenum and ducts.

Unfortunately, the manual does not reveal the control protocol. I would expect the most common failure mode to result in the blower being stuck at highest speed.

According the Toyota service literature, the climate control system stores malfunction codes the dealer technicians can read with a proprietary scan tool.