94 passport ac/alt.electrical

Just been working on putting in a new compressor,drier,flushed lines,vacuum tested and charged. Well on driving truck to mechanic to have it charged my alternator went bad. Last night put in a remanufactured alternator and my ac works but after a very short time the compressor clutch cycles very often(like a turn sugnal gone bad) The ac light blinks on and off and my brake and battery lights come on. Is this a bad junk alternator? Or is a pressure switch that has crapped out to blame? Ruled out relay. Read some other forum posts that say remanufactured alternator is crap. I've got 12v at rest 13.9v running and when i put on ac the compressor clutch engages and the voltage drops down to 11.4 and clutch disengages,voltage goes up clutch engages again. This cycles quickly. shut off ac button and works again charging to 13.9 eventually.I'm just a rainy day mechanic but i think that the "NEW" alternator is not working right or it's having problems regulating the voltage.

No takers?
electrical in title must have scared most off. It is obvious there is some sort of switch or relay that shuts off the compressor as voltage gets low. If I rip out the new alternator and check it it would probably test out ok because it is indeed charging, but that charge isn't enough when the ac is running. works for quite a while idling at night but fails as soon as rpm goes up increasing electrical load on compressor.

Most likely the alt is to blame.

Isuzu's are VERY picky about their voltage, and they will eat alive most aftermarket alt's.

Mine gobbled one up in less then 2 weeks last summer - but the damn truck kept running, just weirdly, as no one believed that the alt was bad.

Switched out to a BOSCH alternator, haven't had an issue since.

I second the alt. I replaced mine w/ a bosch. The first one was bad right out of the box- made the brake light and batt light come on and made the fan kick off. So far my second one is working well.

I vote bad alternator as well. About 4 years ago I went through two reman. alts. in 10 days (the second one lasted about 4 hours) before I went and got one from the dealer.

Thanks for all your help! ripping out reman. and diggin a little deeper in my pocket.