I've had my 06 FX4 5.4 (FTX) since September of last year. This summer the performance of the AC has been reduced significantly due to use. I did some research and found this tends to be a typical problem with the 04 - 08 models. I'll see what I can do here to describe how I fixed it and answer questions if you all have any.

Problem: A/C was not blowing cold enough air at all positions of blower speed. Lowest temp was around 70 degrees at idle. At higher RPM it would go down a bit more, but was never comfortable.

Indications and diagnosis:
After hooking up A/C charge gauges to see what my pressure was I found that:
1. discharge pressure was too low
2. suction pressure was too high
3. idle pressure was sufficient - meaning that it wasn't caused by insufficient charge.

Possible solutions: reed switches in the compressor not working properly (need to replace compressor) or Orifice tube/expansion device not working properly (needs replacement).

The game plan was then simple. Replace both and replace the accumulator while I was at it. This was an 8 hour (yall 4.6's have the A/C on top the motor so it may go faster) job with a friend that cost me about $300. But it was better than the $1200 I've heard others paying on here for no results from the dealership.

Step 1. Purchase accumulator ($60), compressor ($188 - $260 if you go with MotorCraft) and orifice tube($20 [yes there are $3 ones, but if it doesn't work do you really want to get under there and do this again?]) and 32oz of R-134a. Rent vacuum pump from AutoZone (they charge $180 but refund when you return it.) Rent a fan removal tool - you will need this to give yourself room to get the compressor back on if you have the 5.4L. Get Air Compressor oil - I got the medium grade that you can just pour into the new compressor. If you want to know how much to use, look on the the radiator cover under the hood... you know that little diagram that shows how your belt goes on? R134a capacity and compressor oil capacity are right there beside that diagram. I guessed and fortunately got it right. And found that only after all the work was done.
You will also need to use a fuel line removal tool.

Step 2. Vent the system. They say take it to an approved shop to do this. - Yup thats what I did . They will ask at Auto Zone when you rent the Vacuum pump if your system is empty... yup (cause we would never vent to atmosphere would we? even though R134a isn't harmful to the 3 toed sloths - no CFC's)

Step 3. Remove parts:
-disconnect battery - put your windows up if working outside. Beware if you have a remote start and reconnect battery, the car may start... my engine ran for about 20 sec with no cooling water or oil pump after I had the belt off because I temporarily reconnected the battery at the half way point.
Remove passenger wheel well.
Remove radiator cover
Remove fan shroud (2 bolts)
Uncouple fan using rented tool (this will require some torque)
- with shroud unbolted and fan uncoupled, you can take both out together.
- Remove air intake box - be gentle with your mass air flow sensor assembly. You will have to disconnect some electrical connectors for this
- remove electrical interference by passenger side fire wall.


Step 4.
De-tension the serpentine belt and pull it off totally - $12 to replace if it needs it this would be a good time for it. I just used a 1/2" drive to do this.

Step 5.
Compressor removal - Only 3 bolts hold the compressor to its housing on the under side of the engine. Remove them. One more bolt on top of the compressor holds on suction and discharge hose. This one more was not fun to take out. We had to use several extensions to the ratchet and come at it from the top. (Be aware that when reconnecting, if you don't have it on perfectly, your system wont hold a vacuum and you wont be able to refit the 3 compressor bolts to the engine properly). Electrical disconnect for the compressor will need to be removed also. This is the first part of actually breaking into the system - ensure you are vented before this step. Oil in the lines will leak out also.

Step 6.
Remove the Accumulator - 2 bolts hold it in place. Unbolt and uncouple it; there is one line going into it and one coming out.

Step 7.
Remove the hoses going to the fire wall on the high and low pressure side. Fuel line removal tool was needed here. This is where I found out that the idiots that worked on the A/C before I bought the truck didn't reinstall an orifice tube, so it was running with out one. This was the whole problem.

Step 8. Install orifice tube in High pressure side. Arrow's on tube tell you which way to put it in. Reconnect hoses going into firewall.

Step 9. Fill Compressor with compressor oil - 8 oz.

Step 10. Install Compressor. The bolt I mentioned earlier may give you trouble here too. Ensure its on and the suction and discharge lines are properly mated for a good seal.

Step 11. Remove and connect new Dryer

Step 12. Use A/C gauges and vacuum pump to draw a vacuum on the system when you have everything reconnected. After you have a vacuum, hold the system there for about 30 min. You should be still at 30" Hg, or perfect vacuum if your hoses are all reconnected correctly. You will have to do this a few times if you have any residual R134a in the system. It will re flash when pressure drops, causing a pressure rise once you turn the pump off.

Step 13. Re-bolt the air compressor to engine - 3 bolts... this will prove to be a challenge and was very time consuming. My hat is off to you if you dont have problems with this step.

Step 14. look down lines and ensure all connections are tight and A/C system is ready for charge.

Step 14. Charge R134a... I used 3 cans of 12 Oz each... probably need to vent a bit off. You can hear accumulator percolation when you kill the engine because its a bit over charged.

Step 15. Reinstall the serpentine belt. Follow diagram on radiator cover.

Step 16. Reinstall Electrical interference around passenger side firewall.

Step 17. Reinstall Fan and shroud.

Step 18. Reinstall Radiator Cover.

Step 19. Reconnect air intake box.

Step 19.5. Reinstall wheel well.

Step 20. Reconnect battery terminals.

Cycle engine from on to off a few times (that is turn on all electronics with key without starting engine). Then start engine and turn on A/C.

It worked quite well at first, and since has only gotten better. Just like before, the air gets colder at higher engine RPM.

Now I just gotta find out about wrapping the discharge side hoses for insulation and what the heck this blend door motor is to get it even colder.

Let me know if yall have any questions.
-Best

 

Nice work there. Glad that you got it working again.

 

After that job, the blend door motor replacement will be a breeze!