4440 AC compressor

[WP77]

Bought this 4440 in January. Was told AC works great. Now its hot enough to need it and of course it doesnt work. Has been converted to a Sanden compressor and R134 by previous owner. Clutch wont engage, so I tried jumping it. Figured out theres no power to the yellow hot wire. I was able to jump the clutch from another source and it engages, but out of Freon of course. Since the yellow wire is not hot with the AC switch on, how do I trace it down? Yellow wire goes into harness in fuel tank area and from there I have no idea.

 

[rockcreek4630]

Does it have the fuse or did they put in pressure switches most conversions used the switches if so you need freon for the power to get to the clutch.

 

[wore out]

(quoted from post at 12:45:50 06/28/22) Does it have the fuse or did they put in pressure switches most conversions used the switches if so you need freon for the power to get to the clutch.

Yes, there could be pressure switches in the liquid line up on top of the cab if non are visible at the compressor..

 

[WP77]

It has the low pressure switch on the compressor. What I'm saying is the hot wire to the switch doesn't get hot like it should. Usually you can just jump the switch. I can engage the compressor clutch by jumping a hot from the starter to the clutch. I guess I'll go ahead and charge it that way and rule out if there's another low pressure switch somewhere.

 

[WP77]

I jumped the clutch and added freon. Got it cooling decent and now the clutch stays engaged with the switch on. So there must be a 2nd low pressure switch somewhere. Thing that was weird is low side showed a vacuum when I started. Signs of a bad expansion valve if memory serves me correct.

 

[Cliff Nelson]

If you're saying low side vacuum before adding freon that would be normal for a low freon situation. If pressures are good with it fully charged there should not be any problem.

 

[tim s]

Power from the fan switch goes to the cold switch, then on to the compressor,,from the cold switch it travels down the right cab post, through a connector above the right battery,, up above the engine to the right top of the radiator, through another connector then on to the compressor, the original route takes the yellow wire past the lower left of the radiator tucked in with the ac lines,, this is a good place for a short to happen..when I am dealing with faulty wire harness, I run a new wire from the cold switch down the left cab post and up past the starter.