Perplexed - 2006 LS A/C challenge

[Riverstory]

Thanks in advance to any and all for reading this lengthy message. And providing much appreciated feedback.

Facts in order of occurrence-

• I acquired a 06 LS approx. 6 weeks ago. It has 117k miles and I purchased it from a neighbor who owned it for 6 years. Therefore I have access to recent history.
• The car had zero road time over the last 12 months but had been started once a month until it warmed up. Doesn't take long to warm up in AZ heat.
• I acquired it with 3 known issues - Overheating, hard trans shifting, A/C inoperative.
• Overheating and hard trans shifting parked the car 1 year ago. Inoperative A/C only occurred within last few months.
• When I brought her home, I immediately attempted a fix on the A/C system. I will address my unsuccessful attempt to fix and observations later in this post.
• Learned of LVC forum. Awesomeness.
• Acquired Ford shop manuals, Ford wiring diagram manual, Ford Powertrain Control/Emissions Diagnostic manual
• Trans shifting issues - fixed with solenoid pack, filter, and exacting fluid fill.
• Installed Forscan on an old laptop and purchased 2 adapters, the second one being the winner. (Thanks Joe for the adapter guidance)
• Overheating - fixed with ALL new cooling system components including radiator. Thanks to all of you that previously addressed this issue with pics and guidance. Yes, I removed the IM. Easy stuff. (Thanks Devin for the DCCV/Recirc pump harness)
• Returned to my A/C repair efforts

Disclaimer - I have limited A/C experience but do own vacuum pump and manifold gauges and have successfully completed repairs on some of my other vehicles.

When I first purchased the LS, my initial attempt at repairing the A/C system was to hook up my manifold gauge set and test for pressures. Zero pressure on both low and high. Because of my limited A/C knowledge, I knew that zero pressures meant a leak and that sometimes because of a slow leak, you can add R-134 to engage the clutch (after vacuum). With A/C running and after adding less than 12oz of R-134, the low side pressure came up to approx. 20 lbs. and the high side only to 30 lbs. And the system would not accept any more R-134. I then observed that the clutch did not engage. So, thinking that the clutch may have failed, I disconnected the clutch wiring from the main harness, added and removed 12V to the clutch wiring, and then observed positive clutch engagement and disengagement (engine not running). Then I unsuccessfully attempted to add additional R-134 with engine running and "forced" clutch engagement. I ran the engine no more than 10 minutes attempting this procedure. No change in the manifold readings nor acceptance of any additional R-134. By this time, my cooling system components arrived and I turned my attention to successfully repairing the engine overheating condition.

Observation - After initial A/C repair attempt and prior to the coolant system repairs, I noticed a few drops of JAG oil on the garage floor. Then traced them to rear of the A/C compressor. I wiped them up and have not observed them since. And I now believe that this is a simple repair.

Yesterday, I again hooked up manifold gauges, observed zero pressures, no clutch engagement and thus began my research using LVC, shop manuals, and Forscan.

FORSCAN
Using Forscan, I ran the limited A/C PID functions and they all report normal behaviors. The A/C pressure sensor reading shows 30psi.
Using Forscan, I ran EATC module test with successful results.
Using the built-in Lincoln diagnostic DATC s/w, I successful ran both the on-demand test and the continuous test - no issues or faults.

Shop Manuals
I've read on the forums where disconnecting the evaporative discharge temp sensor (EDTS) has allowed the clutch to engage. The shop manual states either a B1946 or B1947 fault is a shorted or open EDTS. I have neither fault during DATC reporting.

LVC Forums
In ~4 hours of reading and re-reading, I cannot conclude nor deduce that this issue has appeared before.

I'm thinking it may be a plugged TXV but am praying that I'm wrong (dash removal-ugh). I can't seem to find any information on LVC about troubleshooting a failed TXV so if you could share, I would very much appreciate.

Sorry for the long thread - I wanted to ensure that y'all had the complete picture. Thank you. I'm hoping to avoid a trip to the dealership.

 

[joegr]

I really don't understand why you are thinking TXV or anything else complicated. Why look at the evap sensor for keeping the clutch off when you say there is only 20 to 30 PSI pressure? That is enough to keep the clutch off.

A clogged TXV would result in very high high side pressure and low low side pressure.

PAG oil leak at compressor - Probably the scroll control valve o-ring. You need to fix that, remove compressor, drain and refill with oil.
System open (zero pressure) - Need to replace the dryer. It is completely ruined at this point.
Charging - You can't charge from zero. You have to pull a full vacuum. Run the vacuum pump (with new dryer in) for at least 30 minutes. Turn the pump off and make sure the vacuum holds for at least an hour.

Add one can. (add to system that is still at full vacuum) Note that you can't have a different pressure on the high side than the low side if the clutch isn't engaged. If you do, this is telling you that your gauges are bad.
One can may or may not get you to high enough pressure to engage the clutch. You need about 50 PSI for that.
You may have to disconnect the pressure sensor to get the clutch on to pull the rest of the can in. If that doesn't do it, then your port adapter is the best suspect. I have seen plenty of the cheap ones not open because the LS port valves pins aren't very long.

 

[Archangel]

I've seen that first hand being an HVAC service man for 30 years. Gauges go bad, schraeder core hose depressor inseret on hoses gone bad and yes, I even recently threw away one of those automotive charging hoses with the screw on, valve-to-can with the hose plugged up.