2018 F150 XLT 5.0

Looking to expand on my knowledge a bit. Maybe have a few experienced people agree or disagree with my thinking. Let's keep the conversations on topic and professional though.

I will start off with a disclaimer that I have a modified a/c system so this isn't a factory issue or anything like that.
If something is wrong or a real issue here the fault is only my own and I take full responsibility on this.

Now that that's out of the way.. I installed a chiller system on my truck last year. In short, this uses the a/c system to remove heat from the supercharger's intercooler fluid. Same principle used on Dodge Demons.

About 6 months past my initial install my compressor ended up going out. When I was diagnosing I noticed I had a refrigerant leak on the modified suction line that I tapped into. I'm sure this is why the compressor went out. I believe the leak to have be caused by a bad fitting that was used so I had a shop make me a custom hose and it's worked out great.

Problem:
Fast forward another 6 months or so and the system has been working great until the other day. I started noticing cabin temps creeping up to 55* and now 60*. It's usually consistently 45*.
I put my gauges on and i'm reading 50-60psi on the low side and 150-175 on the high side. Ambient was about 90*. I would figure I should be seeing ~35psi on the low side and ~210 on the high.

Troubleshooting:
First I thought maybe the charge was low so I first added an additional 0.5lb to the system. Pressures rose along with cabin temps indicating an overcharge so I scratched that.

Had the system evacuated and pulled a fresh vacuum and recharged to 2.5lb. Factory system calls for 1.81lb but with the additional a/c lines and chiller it's recommended to add additional refrigerant. Pressures are the same and cabin temps only drop to 58-60*.

I have had the system open twice now. One during the initial install and second to replace the compressor. Admittingly, I have not replaced the drier either time as I should have. Would this cause those pressures?

Other than that the only thing I can think of would be a bad txv. When I run my truck at the track I have a drag valve which shuts flow from the evap coil to prevent dripping at the track. When I open this valve back up to allow proper flow to the evap coil I can hear a surge of refrigerant flow. Could this have possible damaged the txv? Other kits shut flow on the liquid line instead of the suction line which makes more sense to me. I went to the track the day I started noticing this issue and also ran the valve closed the day prior when I was prepping for the track. Coincidence?

I know some may say the system just does not have the capacity for the additional load. This may very well be true but I just find it weird that I have not had any problems keeping up with the demand until the other day. Even on 90-100* days. Any ideas?

Here's a quick and dirty diagram of my system for the visual people like myself:

 

I should add that today when I was diagnosing the truck I closed the drag valve which shuts flow from the evap coil. Supercharger fluid temp dropped from 60* down to 40-45* which is about normal for a 90* day just sitting at idle. Then, I opened the drag valve back up which allows flow from the evap coil again and temps quickly came back up to 58-60*. Took the truck for a quick test drive and cabin temps dropped down to about 50-52*.

 

Is the door for the heater fully closed, if there is one?

 

Funny you mention it. I have started to notice a clicking sound coming from behind my radio head unit.

 

I had similar problems on my stock '11 5.0. Turned out to be a faulty expansion valve. However, I'd expect to see higher pressure on the high side if your valve is failing. One symptom of the bad valve was the fans were operating at full speed all the time - it assumed that because of the high pressure on the high side, the engine was running hot and it kept trying to cool it down.

 

My gut feeling tells me I either have some trash in the txv causing it to stick. Or the increased heat load with the chiller is maxing the system and with temps rising i'm starting to notice it more.

 

Range for 90ºF ambient is 36-58 suction, 175-235 discharge. You definitely are well outside spec... near the high limit for suction, below the low limit for discharge. Stuck TXV, internally leaking compressor. For a blend door issue I'd expect to see lower suction side pressures.

Were the new parts flushed, and a solid vacuum pulled after install?

 

System was not flushed. I did hold a solid vacuum though.

 

Cutting oils and debris can be left inside new parts if not flushed with the appropriate solvent. Sometimes they just don't let the flush run long enough. Never trust that an a/c or cooling system component has been properly cleansed, even one from a dealership.