How hard is it to replace the "complete control head assembly"? on 2004 Toyota Sienna

My rear air blower is not working again. Last year when this happened toyota replaced the rear blower motor and transistor and say that this time the problem is "1 module is not sending a signal to the rear blower motor and only solution is to replace complete control head assembly". They have the part as an A/C amplifier and I am told it is in the dash so there is a lot of labor. Total cost $1000 so I want to see if I can find the part at a junk yard and do it myself.

Asked by for the 2004 Toyota Sienna