Any ideas as to why the wire that turns on the ac at the relay on the drivers side is always hot? I cannot find where it goes to from the fire wall and haven't found the diagrams in my service manual.

 

what side of the firewall. if you mean under the hood one wire should go to the eletric clutch.

 

No, on the inside of the cab.

 

odd... I know on 88 and 93, the AC controls are vacuum... and they go out on the passenger side... But then, I havn't really looked to see if there's any power hooked up to the thing too or not.

You could try measuring the ampreage going over the wire, if someone replaced the original wire and the one they have is rated for 5amp but it's servicng 20 amp, that could do it.

 

The only relay on the 89 AC system that I know of is the wide open throttle relay that cuts off power to the AC clutch when you floor the gas. You have power thru the relay unless the computer sees a wide open throttle condition.

 

Yes, but the line out of the firewall is always hot even with the ac off. It looks like I'll just have to trace it down, I was kind of hoping somebody else had this problem and stated what they did.

 

The 14 GA brown wire is always hot as it feeds off the fusible link. The 14 GA dark blue with black stripe goes to the AC clutch thru a bi-directional Zener diode. The 20 GA dark blue with orange stripe goes to the AC switch inside the truck after it passes thru the AC damped pressure switch on the heater valve dash panel right side. The 14 GA dark blue wire goes to a J2 splice that connects to pin 2-4 on the computer. Pins 1-45 and 1-56 on the SMEC also go to the AC switch.

 

Thanks.