Alternator/ charging problem 89 740 turbo wagon

[David Shea]

I live in Las Vegas, NV and I have had problems for the last 3 summers with low charge voltage when the car has ran for some time with the A/C on and the engine has become heat soaked. The voltage gauge remains in the middle of the operational arc- even after the A/C has been turned on but will gradually decline until I start having the shift down light start to glow. Prior to some recent work which included: 1- taking the alternator to a local shop for overhaul at which time they said that it was putting out fine and they only replaced the regulator and the bearings. 2- replacing a bad looking ground wire and cleaning and tightening the chassis and engine ground wires. 3- replacing the belt and putting it from the harmonic blanacer to the alternator rather than the water pump pulley to the alternator ( the harmonic balancer pulley is a larger diameter than the water pump- but must be the same length for some one from one of the shops that have worked on it to route incorrectly) and making sure that the belt was tight 4- cleaning the battery connections and servicing the eletrolyte to the proper level.

The c charging system seemed to perform much better and the weather cooled off some so the voltage needle stayed right in the middle of the arc. Since it has gotten hotter though the problem has reoccured.

In the mornings when it is cool the alternator whill actually charge at about 13.5 or better volts for a while then will return to the middle range. In the fall and winter the charging system is not a problem.

Does the heat stress on the alternator which makes a low whining sound when it is showing low voltage output- cause something inside the alternator to go crazy??

I don;t know what else I can do at this point.

David Shea