O/D light flashing only when a/c is on

[Longesst]

Hey guys, 93 idi, over drive light flashing only when iturn the a/c on. Swith shows .5 - 4.5 volt range. Set at .8 volts at idle. Drives fine, turn on the a/c and light flashes. Any help would be great. Thanks

 

[NJKen]

Thats a good one! I would check the grounds on the engine and find the diode for the AC. When the clutch dissengages it will create a voltage spike that is not good for electronics. The diode in the system supresses these spikes. I think the 93 has a power the power distribution block under the hood that has a diode in it for the AC. It looks like a maxi fuse but has one blade on the bottom sideways. If you have that pull it out and check it with a good multi meter that has a diode check function. Start there and repost.
Ken

 

[Longesst]

Thanks ken. While checking voltage on the tps I was getting a voltage increase of .1 volt when the a/c was engaged. Now, if I left the a/c on and unpluged the connection I got no movement in voltage. No change when I pluged it back in either. Now the best part... It's back to normal now. I see that the compressor wires run along side of the wires going to the tps. Checked them all the way back and found nothing. Maybe something in the dash?!? I'll check the diode in the morning

 

[NJKen]

Start with the diode. I cant think of anything under the dash that ties the 2 together. I am still on the diode or a crummy ground.
Ken

 

[NJKen]

Any progress? This one has my curiosity.
Ken

 

[trackspeeder]

Any progress? This one has my curiosity.
Ken

Same here.