97 GMC Sierra AC
 

New to the forum, glad i found it. I has a question, Lately I have been noticing that when I run my AC, my voltage drops, and it does not seem to be getting as cold as it has been in the past. Could it be that my compressor is going out or is this another issue. I could really use some help on this as it is extremely hot here right not.

Thanks in advance for any help.

Need to look at electrical like cable connections on the battery and alternator.

The only time that the voltage drops is when I turn on the AC. As soon as I turn the AC off the voltage goes right back up. I am starting to wonder if the Alternator is starting to go out and cannot handle the load. It is only 3 years old so hope not.

Well it just depends. That A/C load could be the threshold for a weak cable but also for a weak alt. Have a parts store do a load test on it to be sure. You dont even have to take it out, just drive it up there.

Would a AC compressor that is going bad pull too much amps and cause this, or is it most likely the alternator/cables?

No if it did that then it would pop the fuse cause the power wire feeding it is only signal wire. If the comp is going bad you would hear it, or sometimes the idle comes down too much when it engages cause it puts more drag on the engine.

Sounds to me like the computer is not getting the signal that the A/C is on so it can bump up the idle........voltage drop could be loose cables or a failing alternator or battery.....my burban does this too but only when i turn on the 2 blower motors.....as far as not blowing out as cold of air have you had the charge in the A/C system checked? it could be low....or you could have a control unit issue......fairly common on these body styles.

The coldness issue started at the same time as the voltage drop when the AC is on, have never had a problem with it getting cold before that time.

Guess I will start with getting the alt checked and work from there.

Check the connector to the A/C clutch and the connector to the clutch cycling switch....is the clutch engaged while the voltage is low?............yea some times mine takes some time to get cold.and seems to be associated with a voltage drop.....but it is intermittent. Im gonna bet the alternator will test fine(as did both of mine that i have had) I think its the control center that is the issue.

Yes the clutch is engaged when the voltage drops. I will check all the connectors tomorrow, gunna try to figure it out then and see what I can come up with.