A/C Compressor diode
Thread Starter
Racer
Joined: Apr 2006
Posts: 405
Likes: 1
From: Twinsburg OH
A/C Compressor diode
I have been having trouble with my A/C lately and from what I can figure out I may have a bad diode on the compressor clutch. Problem is I am not sure where this is located. Could someone let me know where to find this diode on my 93?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Usually in the connector, but at some point, GM started placing it in the coil. Diode problems usually damage other components as the collapsing magnetic field allows juice to flow back to the enabling device. For a '93, that would be the compressor relay and then maybe the ECM which drives it, though I've never seen that (ECM damage) occur. Post the exact problem for further help.
Thread Starter
Racer
Joined: Apr 2006
Posts: 405
Likes: 1
From: Twinsburg OH
Usually in the connector, but at some point, GM started placing it in the coil. Diode problems usually damage other components as the collapsing magnetic field allows juice to flow back to the enabling device. For a '93, that would be the compressor relay and then maybe the ECM which drives it, though I've never seen that (ECM damage) occur. Post the exact problem for further help.
What year did it get moved into the coil? Was it in the compressor side of the connector or the other side?
Thanks for the help,
Travis
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I don't know what year it changed, but you might be able to figure it out by looking up the part at www.acdelco.com
I never seen a bad diode on our Vettes.
If you haven't disconnected and reconnected the battery or removed memory power from the Programmer, do so now.
In line with the compressor relay is the Low Pressure switch and if there isn't a complete circuit there, the compressor doesn't engage. The ECM monitors that circuit for rapid on/off's with too many changes of voltage/no voltage indicating low gas. However, if there's just an off or no voltage at the ECM, it assumes that's it's too cold to engage the compressor and nothing - including a troublecode - happens. Troubleshoot by making sure the switch contacts are closed. Jumper the harness with a paperclip and if the compressor engages, the connector is bad. If it doesn't, troubleshoot the relay.
I never seen a bad diode on our Vettes.
If you haven't disconnected and reconnected the battery or removed memory power from the Programmer, do so now.
In line with the compressor relay is the Low Pressure switch and if there isn't a complete circuit there, the compressor doesn't engage. The ECM monitors that circuit for rapid on/off's with too many changes of voltage/no voltage indicating low gas. However, if there's just an off or no voltage at the ECM, it assumes that's it's too cold to engage the compressor and nothing - including a troublecode - happens. Troubleshoot by making sure the switch contacts are closed. Jumper the harness with a paperclip and if the compressor engages, the connector is bad. If it doesn't, troubleshoot the relay.
