Manuals through 2025 now available!
Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.
LEMON is the spiritual successor to CHARM, I recommend you try it!
Link:
lemon-manuals.la or
lemon-manuals.org.ua
(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)
Or, hide this message:
temporarily or
permanently
HVAC Blower Controls Circuit Description
Blower motor speed is determined by the voltage applied to the blower motor. This voltage varies from approximately
4V (low speed) to approximately
12 V (high speed). The voltage applied to the blower motor is controlled by the
blower motor control module. The blower motor speed can be adjusted manually by pressing the fan up or down switches or automatically by placing the heater-A/C control in the AUTO mode. The heater-a/c control sends blower request information to the blower motor control module in the form of a variable voltage signal. This voltage signal ranges from approximately
0.5 V (for low speed) to approximately
7 V (for high speed). An amplifier and driver circuit in the blower motor module supplies voltage
(4-12 V) to the blower motor according to the request signal from the heater-A/C control.