When you switch on the AC, the fuse blows and each replacement fuse keeps blowing. Frustrated that your car’s A/C is not working? Are you looking for guidance on what to do next?
Read on for tips and suggestions on what to do next if you find yourself in this situation.
What Causes the Car AC Fuse to Blow?
The AC fuse can blow immediately the AC switch is on or it may blow after several minutes of the AC running. An immediate fuse blow is likely a sign that there is a short.
1. There is a short in the wire connection to the compressor. A short to ground of the 12V DC wire connection to the AC compressor will blow the fuse.
The wire can be damaged along its path as it bends around a corner for instance.
To confirm if it is indeed a short in the wire connection – Disconnect the plug supplying power to the AC compressor, replace the fuse, switch on the AC and monitor if the AC fuse blows.
You can also use a continuity tester to test for a short in the wire connections at the end of the 12V terminal in the AC plug and the ground connection.
A continuous tone (if the meter is set to test for continuity) or a zero ohm reading is confirmation that indeed there is a short.
Better still, you can use a DC clamp meter to monitor the current flowing through the amps to check if there’s any current flowing with the AC plug disconnected.
A high current flow confirms a short in the wiring to the AC compressor.
2. Faulty blower motor. A short in the blower motor winding can also cause the fuse to blow.
Switch on the blower, first at slow, mid and then high speed. Check if and when the fuse blows.
If the fuse blows then this confirms that the short is in the blower circuit.
3. Faulty compressor field coil. A failing compressor coil can also cause the fuse to blow. Check the wiring diagram.
If it is just the compressor connected to the circuit, you can use a DC clamp meter connected inline with the compressor circuit to monitor the current flowing through the amps.
A current reading close to or over 100% of the rated fuse current indicates a fault in the clutch field coil.
You may be able to replace the clutch, pulley and compressor assembly at competitive rates.
Why Car AC Fuse keeps Blowing?
If the car AC fuse keeps blowing then its because the underlying short is not fixed.
Possible faults include a short in the wiring supplying the compressor, fan blower winding or a failing compressor coil.
Do not hesitate to contact a qualified auto mechanic.
Closing Thoughts
A short in the wiring, a faulty blower motor or a faulty compressor coil can cause the AC compressor fuse to blow.
Inspect the wiring, monitor the current flowing through the wiring. You may need to replace the clutch field coil too.
Do not hesitate to contact a qualified mechanic.
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