Toyota ist Scion xA NCP60 Heater Didn't Work

2005 Toyota ist NCP60 Engine Model 2NZ
With Auto Air Conditioning

Situation
The heater did not work suddnly.

Cause
Faulty Air Conditioning Amp(Computer)

Maintenance
A/C switch turned off automatically when I turned on the A/C switch .
Also I turned off the ignition switch and turned on it again.
It happend when the heater blower motor did not work.
I looked into it by maintenance manual.
Then I took off the combination meter, and exchanged the amp where it was back left .
After that it worked properly.