Blower that works on high but not on lower speeds is a textbook blower resistor failure. The resistor pack burns out and only the bypass high-speed circuit remains functional.
Classic failure. The resistor pack provides the lower fan speeds and burns out from heat and corrosion. High speed bypasses it, so it still works. Replacement is usually quick and cheap.
The plug feeding the resistor pack often melts before the resistor itself fails. Replace both the resistor and the connector pigtail or you will be back here in 3 months.
Modern cars without a resistor pack use a solid-state module. Same symptom when the lower-speed transistors fry. Replace as an assembly.
The fan selector switch on the dash has burned contacts on the lower speeds. High setting works because it uses a separate contact.
Broken wire or corroded splice in the low-speed path. Less common but possible.
A motor with worn bearings pulls extra current. Low and medium speeds cannot deliver enough power to turn it. High speed barely does.
Very rare. A failed body module can lose its blower-speed PWM output. Diagnostic scan required.
| Likely Cause | Typical Cost | DIY Difficulty | Severity | Likelihood |
|---|---|---|---|---|
| Failed Blower Resistor Pack | $15-$80 resistor + 0.5-1 hr | Easy | Low | 80% |
| Burned Connector at Resistor | $15-$50 pigtail | Easy | Low | 60% |
| Failed Blower Control Module | $80-$300 module + 0.5 hr | Easy | Low | 35% |
| Bad Climate Control Switch | $150-$500 control head | Moderate | Low | 20% |
| Wiring Open in Low-Speed Circuit | $30-$150 wiring repair | Moderate | Low | 15% |
| Failed Blower Motor on the Way Out | $80-$300 motor + 1-2 hrs | Moderate | Low | 10% |
| PCM or BCM Programming | $200-$800 module | Hard | Low | 5% |
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The blower resistor or control module that provides lower fan speeds has burned out. High speed bypasses it and uses a direct path, so high still works.
$50-$150 at a shop on most cars. The part is $15-$80, labor is 0.5-1 hour. Often behind the glove box and very accessible.
No, but airflow is loud and the motor runs harder. Fix it within a month or two.
Almost certainly yes. Remove the glove box or kick panel, unplug the connector, unscrew the resistor, swap it in. About 30 minutes on most cars.
Often the connector is corroded or burned, creating high resistance and heat. Always replace the connector pigtail along with the resistor.
No. This is a pure airflow issue. The compressor and refrigerant are unrelated.
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