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wkboggan 7/8/2013

2007 Chevrolet Impala LTZ 6 Cyl 3.90L


A/C compressor blows fuse after running a few minutes, changed out accesory parts to no avail. suspect compressor sho

A/C pressor checked ok, changed pressor sensor, acumulator switch. A/C always run cool air until
weather temp is 90 and over, or engine etc is
under load and hot. It blows any size fuse from 10 amps on up. Car has 69,000 miles on it. No engine check light issue.

1 Answer


Jimm 7/8/2013

The a/c compressor short (blowing fuse) may be caused by a faulty a/c compressor clutch - the clutch wire windings may be shorting out due to the hot conditions. The circuit should be checked for proper voltage before testing the coil for resistance. Before testing, visually inspect the coil for overheating and cracking. Heat expands the coil and will create breaks in the windings.

Voltage Test: Remove the plug from the clutch coil and activate the A/C system by placing the selector on cold. Using the 20 volt setting on the DVOM, check for battery voltage at the harness connector. If battery or charging system voltage is present at the plug, test the coil for resistance.

Resistance Test: The A/C clutch coil resistance test is performed with an Ohmmeter. A result of 0.00 indicates that there is a short in the windings and a result of O.L or infinity indicates an open in the windings. There's nothing special about a clutch coil, most are in the range of 2 to 5 Ohms, and any reading below 2 Ohms or over 5 Ohms indicates a bad coil. The diode should be tested as well. Diodes are like one-way check valves because current is permitted in one direction and not the other. Many multimeter have a selection or function for testing diodes. This is because many coils contain zener diodes that allow current only up to a certain threshold. If unsure, check with the manufacturer's manual for specifications and special procedures for performing the A/C clutch coil test

The a/c compressor clutch is also available as a separate item - as long as the component part cost does not equal around 75% of the compressor - and if the a/c compressor is working OK.

Check the many on-line auto parts sources, such as; www.partstrain.com, www.partsgeek.com, www.carpartswarehouse.com, or www.rockauto.com for the replacement parts.


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