Alright, im more of a lurker here than anything, but I bought (back in april) a 99 rcab SD, 5.4, 4R100 trans.
The truck was an old county truck, kinda beat up, but strong. I just need it to tow my race car around, usually no more than 200 miles. I havent towed with it yet.

I had to beat on the blower motor and knock some dirt loose, then the blower worked. The A/C needed to be charged, so I charged it to 28psi, the darn thing would freeze me out of the cab. but its hit and miss, sometimes it works, some times it dosent. Sometimes it cycles, cold for a min, hot for a min, cold, hot, cold hot, cold.....
Any ideas? when its cold its cold. I dont get it.

Also, the tranny shifts rather soft, I changed the fluid and filter twice (1000miles in between) but never drained the torque converter. Im thinking about saving my pennies and getting a new valve body and torque converter for piece of mind. The fluid looks and smells fresh. I also put a deeper pan on, 3 extra quarts. I installed a temp gauge in the test port, now im reading 170 to 180 with no load. its between 90 and 100 degrees here. is that about right? the sticky says between 40 and 100 degrees of the outside temp is about right.... is it? what kind of reading are you getting?

 

for the A/C make sure clutch is engaging sometimes need to pull a shim out

 

Tell me about these shims? how difficult to get one out? The clutch is engaged when the air blows cold, but either dosent work, or cycles. today, its 98 degrees, and its not working at all.

 

i think you need to increase your low side pressure to about 35

 

low side should be 35 to 40 lbs

but it should cycle
first get pressures up think high side is 275
the shim part of it ,I always do a bump test if clutch does not reengage tap clutch with something if it then engages remove bolt in center of clutch hub and remove hub watching as sometimes shims stick to end
remove shims where there will be about.020 between clutch hub and clutch once there replace and tighten center bolt

 

Ill go beat the heat. Its now 100 degrees outside, so its hot. Ill do the bump test, and bring the pressures up. I only have a low side tester, so Ill work with what I got. if all else fails, ill take it to a shop for a r134a fill up.

No word on the tranny temps?

 

trans temps are about normal for towing purposes I would install another cooler to bring them down some,high temps are a big killer for the 4r100

 

i just installed a gauge in mine two days ago and i cant decide if its working or not. it has a range of 140-320 and it has never climbed past 140. the temp here has been in the 80's and raining but i think that is still to low

 

in 80 degree temps that is probably pretty close

 

your idea of a valvebody is good the shifts are slushy on the 4r100,not sure of torque converters on 5.4 but was a weak piece on 7.3

 

ok, so i tried jumping the plug on the lowside. nothing. I tried removing a shim. (im guessing it was the washer looking thing in the clutch, tiny washer on the hub). nothing. its not even cycling today.

 

are you getting juice to lowside plug if yes are you getting juice to clutch

 

how would one check for juice to the low side plug? with the engine running and ac on?

The cluch seemed to be pretty worn. could I get away with looking at the junk yard for a new cluch? how difficult are the clutches to get off?

 

check for 12v a/c on ign on, low side plug should be hot (battery voltage) on both sides while plugged in and one side of compressor plug should be hot (battery voltage) the other side ground

 

That shim is behind the clutch and adjusts the air-gap on the clutch. If you didn't have the clutch off already, you didn't find the right shim The thing with the air-gap is, start the truck, turn on the AC and it works. Then it starts to get intermittent as the engine warms up. If the air-gap is too big it's a hit or miss thing as to whether the clutch will lockup or not. The "bump test" is a good thing to try - just be careful. Tap the clutch face with a screwdriver handle, piece of wood, anything you can get in there and not get sucked up and thrown back at you If you tap it, and it engages, it's the air-gap.

The tranny temp is a bit high, but what are you doing when it gets this high? Driving a lot of stop-and-go? Or are you on the highway, and getting 180-190 degrees? If that's highway, that's pretty high.

My 2001 w/V10 gets up to about 150 - and sits there all day, whether it's 95 degrees out or not. But I have a huge tranny cooler. I think your V8 might have a much smaller cooler, or none at all except for the one in the radiator. Check the lines coming from the transmission, and follow them up to the radiator. If they only connect into the radiator and not into an external cooler between the radiator and the AC condensor, I think that 180-190 is about right.

If you DO have an external cooler, make sure it's clean and not clogged up with bugs/crud/dirt/mud.