I installed a 1992 3.4DOHC in my 1988GT a while back and the A/C never worked. I'm redoing some of the harness because of heat damage at the firewall. I did find an error in my work that is probably why the compressor clutch was not being energized. Now I'm looking at the harness plug itself. The GM service manual shows a diode across the plug, but mine has none that I can see. Should there be one?

Thanks,

Neil

The diode provides for protection for the relay contacts. It is possible that the diode is not located at the connector. It won't hurt to have two.

Make sure the diode is installed in the direction provided on the print. In normal operation the diode will not conduct. When the relay opens a counter voltage will be generated by the collapsing magnetic field. This voltage will cause a slight arc in the relay contacts. This repeated arcing will over time damage the contacts of the relay. The diode will shunt this counter voltage and keep the relay contacts from being damaged.

Use a 1N1002 up to a 1N1007 diode. Paypal me $1.00 and I will drop one in the mail for you. gofast@reddevilriver.com

[This message has been edited by phonedawgz (edited 05-25-2014).]

quote Originally posted by phonedawgz: Use a 1N1002 up to a 1N1007 diode.

In the interest of accuracy, shouldn't that be 1N4002 through 1N4007?

[This message has been edited by Marvin McInnis (edited 05-26-2014).]

Well, crap. I think I found the stock diode in my harness. In the melted length of the wiring is a heavy, dual wall piece of shrink tube that both the dark green and the ground wires to the A/C clutch pass through. I say crap because I thought that was my wiring error when I first saw it.