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03 Grand Prix GT
Hi all i have a quick quesstion, my blower motor only works on settings 3,4,5.
not on 1,2. the old GM's had a seperate fuse for the hi fan setting, is the late model grand prix the same way or is this a problem with the switch.thanks for any and all help. DENNIS |
It's a problem either with the switch, or with the printed circuit board that the wiring harness plugs into.
I'm not sure how to deceipher which is bad. A gearhead will be able to tell you that soon. |
Hmmm
My first thought would be a resistor for the various speeds...but really not sure. |
Originally Posted by BillBoost37
Hmmm
My first thought would be a resistor for the various speeds...but really not sure. For speeds 1-4 there should be a set of resistors for the speed settings... IIRC the High speed seting should be controlled via a relay... and this if the W Body is similar to the H and C body GM's which I think it should be.. __________________ Best Car Insurance | Auto Protection Today | FREE Trade-In Quote |
This is the description of operation for your year. I'd agree that it sounds like a resistor or two may have opened.
The HVAC control assembly applies voltage to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request: * Low speed: 4 resistors * Medium 1 speed: 3 resistors * Medium 2 speed: 2 resistors * Medium 3 speed: 1 resistor When the operator requests High speed, the HVAC control assembly applies voltage to the blower motor relay through the high blower motor control circuit. The voltage energizes the blower motor relay, connecting the blower motor to battery positive voltage. Low Blower Speed When the Low blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the low blower motor control circuit. Voltage is decreased across 4 series resistors to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly. Medium Blower Speeds When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 1 blower motor control circuit. Voltage is decreased across 3 series resistors to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly. When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 2 blower motor control circuit. Voltage is decreased across 2 series resistors to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly. When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistors through the medium 3 blower motor control circuit. Voltage is decreased across a resistor to achieve the desired blower speed. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly. High Blower Speed When the High blower speed is selected, the HVAC control module applies voltage to the blower motor relay through the high blower motor control circuit. The blower motor relay is internal to the blower motor resistor assembly. The voltage energizes the blower motor relay, causing the blower motor to be connected to the battery positive voltage circuit. The blower motor is grounded through the blower motor resistor assembly and ground circuit of the blower motor resistor assembly. Off Mode When the OFF position is selected, the HVAC control module applies voltage to the off blower motor control within the HVAC control module through the off blower motor control circuit. When the HVAC control module receives this input, any A/C request will be cancelled and the A/C request LED will turn off. Fresh air will still be brought in from the outside. |
Blower Motor resistor. Common problem on GM vehicles.
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