The AC/ heat blower fan doesn't work on the low or medium settings but only works on the high setting. Also, the high setting isn't as strong as it used to be. Is this the switch or the air control module?
My car has 96000 miles.
My car has an automatic transmission.
Hey there. The most common failure where the fan only blows on high is the blower motor resistor. It is possible the blower motor switch is the culprit, and it can be replaced separate of the control module.
Diagnosing this should begin by removing the blower resistor and inspecting it. In most cases, it will show obvious signs of failure in the form of melted plastic of burnt wires. If this is the case, replace it. If not, you will need a test light and a wiring diagram to confirm the switch is working.
Testing the switch can be done in two ways. You can use a multimeter to test for continuity through the switch to ground, or you can use a test light and connect the alligator clip side to power and touch the test light end to each terminal of the blower motor resistor connector. Make sure the blower motor connector is disconnected from the resistor. The black and white wire is the only wire that should not be tested. All the other pins in the blower motor connector are paths to ground through the blower motor switch.
If you should require further assistance with this, I recommend having a certified professional inspect the electrical issue in person so it can be corrected.
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