2001 AC problem - Not Blend Door - Back is colder than front but not cold enough

[Jwoodring]

I've been researching everywhere I can find.
Checked blend door, functions and seals.
Ran Diagnostics on automatic AC, checks good.
Pressures at 5-10 min idle with front on max ac and rear on 3.
Low = 48
High = 250 ish
When I turn the rear off, the pressure on the low side drops below 40 and the air out of the front gets warmer. When I have the rear on high, the pressure builds back up to 50/250 and the rear is kinda cold and the front is cooler than outside air but not by much (the rear is slightly cooler than the front).
I cut a hole in the plenum to test the blend door and noticed the air from here fluctuates cold and warm. The warm does not come from the blend door, it just fluctuates. The Evap is kinda warm to the touch but the pipes on the bottom are cool and has condensation.
Why does running the rear AC make the air all around a bit cooler? And what could be keeping everything form being cold as should be?

 

[Jwoodring]

Update. Just running the front MAX AC (rear off) the pressures are 40/low and 230/high

 

[stamp11127]

Start at square 1. You need to know the static pressure in the system once the low and high sides have equalized. You also need to know the ambient outside temp when taking the reading. The static pressure and outside temp should be close to one another.
Has the system been opened recently? Has any r134a been added?
Is the fan clutch working properly?

 

[Mr Bean]

What stamp said with the clutch.

 

[Jwoodring]

I have not taken any other readings. The system has only been open to add r134. Aprox 36 oz have been added. For the first 20 minutes or so the system does not cool as should in the front but the rear is nearly freezing. After a long trip today, on the way up after getting off the highway and slowing to non highway speeds the front suddenly got cold enough we had to turn the fans lower and the rear was nearly blowing out ice. We stopped at our destination for about an hour or so and then started the car to let it cool down (started the trip at 95 degrees outside and humid, on the way back started at 90) only taking about 5 minutes to start cooling. This seemed much more normal to us although the air coming from the front was still warmer and humid compared to the cold dry air from the rear. Back to normal city driving the air in the back was unbearably cold and we had to shut some vents. The front was much cooler but not like the rear. We stopped shortly to eat. After dinner outside air was 85, sun was about an 2 hours from dusk and the AC was cold very quickly. in fact we had to turn the rear to the lowest fan setting and close some vents. By the time we made it back to the highway (about 10 miles down the way) the front was still not as cold and blowing a kind of humid air. We turned front down to the lowest fan setting and aimed the vents away and just used the rear system to cool us to damn near freezing. Now, it's far better than it was before we added the R134 but the front being humid and not as cold is blowing my mind. I know the back has it's own evap so could there be something wrong with the front evap? again, when I'm in the plenum under the glovebox the air inside is mixed. Some is VERY cold and some almost feels like the temp of the engine bay. I could not find any leaks coming from the Blend door. I'm stumped. Thanks in advance. and yes the compressor engages as needed. I noticed that it never really cycles off like my other truck though. As my other truck builds pressure, it will cycle off to regulate. This seems to just sit at a constant pressure and never goes up that much (at an idle anyways)

 

[Petesexpy]

What was the solution? I have literally an identical problem. At 84F outside, the Front blows 70F, the rear blows 58F.

 

[stamp11127]

Petes expy - start your own thread and you will get results.
Usually the "one post wonders" don't really become part of the forum, don't update their results and mostly waste our time when trying to help them.
In your case you will need a good set of gauges to read the high and low side pressures. Some of the auto part stores lend them or rent them out. The first reading you take will be the static pressure after the system has been off for an hour.

 

[Petesexpy]

OK, thanks!

 

[stamp11127]

If you get a set of gauges the second reading you need to take is after the system has run for about 5-10 minutes at idle. You are looking for the low and high side pressures and if the gauges have temp scales those also. That will give you a ballpark temp reading of the evap and condenser.
The third reading is the ambient temp of the location where you are working on the expy.

 

[Jwoodring]

Black death

Actually, it ended up being the black death. The inside of the tubing of the system has a weird black coating. After time it cracks and peels clogging the orifice tube and filter. Replace it with a new one. Fill er up and ice ice baby. My uncle told me about ford using this new material in the late 90s that causes black death, or clogs the entire system. If you can, get it flushed too. I bought us a few years but unfortunately burned up the compressor. It now clicks when the ac is on due to running too high of pressure and letting it get too hot. My mistake for being ignorant on the subject. Still works, just not expecting it to last much longer. But this is the beginning of summer #2 without messing with it and it's still ice cold.