A/C clutch only gets power with a relay removed

[blue83ranger]

Truck is a 1986 ranger 2.9 4x4, formally A4LD now has C4.
If i turn the a/c on and turn the key on, the a/c clutch turns on then off quickly. and if i unhook a relay, (unfortunately I'm not sure what it's for. I know it's not the fuel pump or the a/c relay) the clutch turns on and stays on but the fuel pump doesn't work. someone suggested the relay has something to do with the WOT circuit. So, my question is what are some possible causes for this and what should i check? I'm also running an '88 computer off my '88 which never had any issues. Also we were in the process of charging the A/C. any thoughts?

 

[TomJenks]

Truck is a 1986 ranger 2.9 4x4, formally A4LD now has C4.
If i turn the a/c on and turn the key on, the a/c clutch turns on then off quickly. and if i unhook a relay, (unfortunately I'm not sure what it's for. I know it's not the fuel pump or the a/c relay) the clutch turns on and stays on but the fuel pump doesn't work. someone suggested the relay has something to do with the WOT circuit. So, my question is what are some possible causes for this and what should i check? I'm also running an '88 computer off my '88 which never had any issues. Also we were in the process of charging the A/C. any thoughts?

Ok, I'm gonna make some assumptions here:

The engine is running while you're trying to cycle the a/c compressor.
The wiring harness is basically stock minus the newer computer.
The a/c system has worked in the past, but not now(in other words, it just needed recharging). Or have you opened the system up to replace a part?

What are your gauge readings on the high/low side?

If its not hot outside, the system may not have enough pressure to cycle the clutch for a long time.

Will it take freon? See anything moving through the sight glass on the gauge set when the can of freon is pierced and the can tap opened up? If the duration of the compressor cycle is not getting longer when you are trying to recharge, you might have to put the can of freon in warm water to help get it moving.

Here's a source on wiring diagrams to help you find the function of the relays. Don't know if yours is listed on there or not, but check it out to see:

http://therangerstation.com/forums/showthread.php?t=319

 

[blue83ranger]

all of your assumptions are true and we didn't change any part of the A/C system.
the problem is electrical, i tried bypassing the pressure switch and there's no power there. It does take freon but the clutch only kicks on when you first turn the key on for maybe 1 sec. and doesn't turn on any other time. I'll check out the link and hopefully I'll find something.

 

[TomJenks]

Or you could try this link for wiring diagrams:

http://www.eautorepair.net/Marketing/Default.asp

Its 10 bucks, but better that a chiltons manual at the parts store. Just print off everything you think you'll need before the time expires. Plus, the diagrams are alot easier to follow.

 

[blue83ranger]

i ran a scan for codes and got an 89 and a 95. the 89 says converter clutch override ciruit open which makes sense considering i had an A4LD and now have a C4. and the 95 says the fuel pump monitor has seen a fault in the fuel pumps or circuit. and when i unhook the relay that i don't know what it is stops the fuel pump then makes the a/c work so that seems like my problem, Now i just have to figure out where the problem is for sure. any ideas?