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Introduction to alternators, part nine, alternator components continued

Alternator cooling is a very important process needed to prolong the life of an alternator. Two methods used in the automotive industry are air cooled and water cooled. This article will cover air cooled alternators. Air cooled alternators use various ways to circulate air through the alternator to keep the rectifier bridge or diode trios, rotor and stator from overheating and failing.

Various pictures depicting types of alternator cooling fans.
Various pictures depicting types of alternator cooling fans.
Various alternator cooling fans

The most common air cooling method used is an external exhaust fan mounted on the rotor shaft between the alternator pulley and front housing half. Some alternators have an internal exhaust fan mounted just inside of the front alternator housing on the rotor shaft or on the rotor front pole piece. These fans are called exhaust fans because they draw air through openings in the alternator end frame across cooling fins on the rectifier bridge, over the stator windings, rotor and out through openings in the alternator front frame or housing.

Because of the ever increasing electrical demand of modern vehicles, alternators have been designed to produce more electrical energy by increasing the amperage output. Since the amperage rating is higher, more heat is created. In order to more efficiently remove the heat from the alternator, modern alternators have dual fans on both the front and rear rotor pole pieces. Air is drawn through openings in the front and rear housings, and is exhausted through openings in the side of the alternator housings. This creates lower alternator temperatures thereby increasing alternator life and efficiency.

To maintain optimum alternator cooling performance, the alternator frame air intake openings must be free of debris such as dirt, leaves, chafe, grass clippings, twigs, etc. These openings should also not be blocked or restricted by mounting brackets. Another factor that will reduce cooling is the intake openings located near a header or exhaust manifold.

If an alternator is not cooled properly stator windings will burn and diodes or rectifiers will become heat damaged creating an inefficient electrical supply to meet the electrical demands of the vehicle.

If any of these procedures appear to be beyond the capabilities of the vehicle owner or driver, then alternator inspection and repair should be performed by a professional or ASE Master Certified mechanic. The vehicle would have to be taken to a repair shop that employs these types of mechanics such as A & M Alternator Services located at 2419 E. Jackson St. in Phoenix, Auto Electric Specialists located at 5216 W. Lamar Rd. in Glendale, Village Auto Electric Service located at 19 N. Miller St. in Mesa, All Start Electric located at 13501 E. Chandler Blvd. in Chandler, Tom’s Auto Care located at 63 E. McKellips Rd. in Mesa, Jordan’s Automotive Specialists located at 8718 E. McDowell Rd. #3 in Scottsdale, Rob’s Quality Automotive located at 11801 N. Cave Creek Rd. in Phoenix, Scottsdale Pro Tech located at 8245 E. Butheruand Dr. #111 in Scottsdale, and Art’s Family Auto Repair located at 915 W. Hatcher Rd. in Phoenix. Repair shops that specialize in repairing or rebuilding alternators are Gen-Star Electric located at 6832 N. 63rd Ave. in Glendale, AZ. or C & C Electrical Services located at 3046 E. Southern Ave. in Phoenix, AZ.

As always, before working on any automotive repairs, be sure to wear safety glasses and protective clothing such as gloves and long sleeve shirts to protect oneself from possible injury. Remember, keep the work area safe and follow safety precautions.

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