2006 F250 6.0L Crew Cab Short box with 114,000 miles.
Long story short, before I had my head gaskets replaced my AC worked perfectly. After they were replaced I noticed it would work good for a little while then the compressor would start cycling and the vents would start blowing warm. I hooked up a set of gages and I saw the compressor was cutting out on High pressure (300 + psi). The low side was a little high so I assumed they overcharged it so I bled off some of the Freon and it worked ok until we pulled our 5th wheel a month ago. Hooked up the gages again, still cutting out on high pressure and then when the fan would turn on the pressure would drop and the AC compressor would cut out on low pressure. After doing some research I assumed that the orifice tube was clogged causing the high pressure.

So I ordered a new orifice tube, new accumulator, o-ring kit. I opened up the system yesterday and took out the old accumulator and started draining out the old PAG to measure how much was in there. In the mean time, I removed the old orifice and too my surprise, it did not look too bad. There was only a little bit of debris on the screen and almost no metal flakes, so the orifice tube was most likely not the cause of my high pressure issue. After all of this the accumulator was done draining and I got exactly 6 fl oz of PAG oil just from what I could catch from the accumulator. I'm guessing I lost another oz from the accumulator that I could not catch. I recovered 7 oz of PAG oil just from the accumulator and I am assuming at least 2 oz came out of the evaporator when I flushed it. The whole system is only supposed to hold 9 oz of PAG oil. After discovering this I am sure they (shop that replaced my head gaskets) significantly overfilled my AC system with PAG oil and it was causing my overpressure issue while driving.

My question is, how much oil should I put back in? I really don't to take the compressor off just to measure the amount of oil in it.

Any help would be greatly appreciated.

Jason

 

6oz is a lot from that accumulator -- I would have expected more like 2
likely that a lot of the oil was being pushed thru the orifice tube -- it would not flow as well a the liquid refrigerant

I don't have an exact answer to your question -- so will see what others post

 

I'd drop and drain the compressor, flush the system, and start over with the base 9oz of oil.

 

All but the last 3 PDFs are from the 2006 Workshop Manual
With the last 3 being from the 2005 Workshop Manual.

 

Yahiko, Thank you for all of the workshop manual PDFs! I had a few of them but having these will bee very helpful.

For an update, I dropped the compressor last night and to my surprise I could only get 1/4 fl oz out of the compressor. I rotated it both ways and tried to drain the PAG oil out of both ports but hardly any came out. On to flushing the rest of the system. When I put everything back together I plan on putting 3 oz of oil in the compressor 2 oz in the accumulator, 2 oz in the evaporator, and try to get the final 2 oz in the condenser. Otherwise I will put 5 oz in the compressor and 2 and 2 in the accumulator and evaporator.

 

If you find you need more info just let me know and I can see what I can do.

 

While the oil is strange not more in the pump, it may not be your (only) problem, since oil should go around. It maybe possible you had moisture in your system. I would evacuate very well, let it rest in between and do it again. With a powerful vacuum pump, it maybe too quick for vehicle, so let it warm up and do it again. Keep doing it several times before charging it again. Also, do you have manifold gauge? It is important because you don't want to unplug a vacuumed system, and charge it. Air will get in there.

 

Pulling a vacuum and locking it off with the manifold set and watching the levels over an hour at the minimum.
Any moisture in the system will boil off at the lower pressures. If the gauge drops the level of vacuum. Then one
of two things is happening. You might have moisture in the system or a leek. If you find things being stable. Let it
rest overnight and see what you have the next day. This is all dependent on if you have the time. If time is tight
then give it at least an hour after it remains stable.

 

Sorry about the delayed follow up! Had to work out of town then had my youngest birthday party plus it was 110* heat index for several days.

Anyways, I pulled the AC compressor and I could only get 0.5 oz out of it. So I flushed the rest of the system put 3 oz back into the compressor 2.5 oz in the evaporator and the rest in the accumulator. I pulled a vacuum on it before I left town for work and it was still holding a strong vacuum 2 days later. I borrowed my neighbors SNAP-ON manifold to compare it to my cheaper one and see how deep of a vacuum I was pulling and was almost to -29 in of hg. As it turns out my single stage Robinair vacuum pump that I bought off Amazon years ago did a better job than AutoZone's $200 loaner pump. I did several sessions of pulling a vacuum for 30 plus minutes so there should not be any moisture in the system. Filled it with 42 oz of 134A and it is blowing nice cold air. The head pressure still gets up there before the fan will kick on but once the fan goes the pressure comes right down.

Thank you for everyone's help,
Jason

 

Glad you got cold air

I have a question on your vacuum method
why several 30 minute sessions ? -- why not just leave the pump on until you were satisfied the moisture was gone ?
"I did several sessions of pulling a vacuum for 30 plus minutes so there should not be any moisture in the system"

 

No rhyme or reason. It's whatever I could fit in while running the kids around and other obligations. Since I had to leave the system open for a couple days I wanted to be sure all the moisture was out. I have another vehicle to use so I didn't need it to drive plus I owned the gages and the vacuum pump that maybe has been used 3 times in the 5+ years I've owned them.