[Joshua Hollahan]

My AC and heater blow great, but only when the temps are put to the extreme high or low. The blower only turns on in high. No slower speeds. All fuses are in order. Is this an easy fix or do I need to replace the whole blower assembly? If so, is this difficult?

 

[number9]

The blower only turns on in high. No slower speeds.

No clue about about first part but you can do a self test of AC controller.

Blower speed may be a simple fix.

The ATC ECU operates a blower relay, power transistor and power relay to run the blower at one of 31 stepped
speeds. All speed steps are available in the automatic modes of blower control. In the manual mode, speed steps 3,
10, 16, 22 and 31 are used to provide slow, three intermediate and fast blower speeds. The ATC ECU energises the
blower relay and modulates the power transistor to operate the blower for speed steps 1 to 30. For speed step 31, the
ATC ECU energises the power relay, which switches the earth side of the blower motor direct to earth, bypassing the
power transistor.

 

[p76rangie]

Do not know about the D2, but easier models have a resistor pack that controls the fan speed. If the restores go, the only speed you can get in full speed as this is the only speed that does not go through the resistors.

 

[number9]

That's the same basic component as the "power transistor" and most vendors simply refer to either as a blower motor resistor.
......

 

[sierrafery]

Classic symptom of power transstior failure, the whole assy is expensive but you can change only the transistor on the cooler element, (behind glovebox, looks like this JGN100010 AIR CON BLOWER TRANSISTOR | shop | www.lrseries.com , uyou can check it with a multimeter set on ohm..., unplug it and measure between legs two ways...one way must be much greater resistance than in the other....if resistances are close it's faulty, the transistor is Toshiba 2SD1460, e.g Toshiba 2SD1460 to 3 High Current Switching Applications | eBay