I have been having an ongoing problem with my climate control unit in my truck and it's time to get it taken care of. The problem is my A/C only blows cold on cool days and not hot days! Everything seems to work fine until it gets to be a 90-degree day and then it's blowing luke-warm air. I first found out that the fan clutch was bad, so I replaced it. It didn't change anything. So back to my mechanic to top off the freon at 32 ounces. It did seem a little better, but still not cold on a 90+ degree day! I have seen some places saying, "The amount of refrigerant needed for a 2006 Ford F-150 is 40-42 ounces of Freon" and others saying 32 ounces. The sticker on my truck is long gone! How do I know how much freon to put in?

 

My 04 I'm pretty sure takes 34oz. Did you have your mechanic look at the pressures high and low side while charging it? That gives useful info to diagnose.

But one thing I would suggest is to check your air gap between the front plate and the clutch. If you've got too wide a gap the clutch might slip under higher loads (pressure goes up at higher temps) if it's too wide you may be able to simply pop off the front plate (single center bolt)
And remove the shim washer from behind it and reinstall to decrease the gap. It should be only like 0.020"
Other things are the compressor could just be tired and not putting out pressure, or you could have bad air flow through the condenser. Having the pressure data might offer a clue as to what's up.

 

Factory service manual says 34 oz.

If the clutch doesn't engage, outlet temps will go to ambient plus a bit.

If the mech had to "top it off", it's leaking and likely has an incorrect charge.

 

I used a bad choice of words. He didn't "Top it off" He completely evacuated the system and refilled it with freon and added glow in the dark dye so if it did have a leak then we would know. The confusion is seeing so many different amounts listed for my year truck. If 34 oz it the correct amount, then I am 2 oz low and that may explain why I am OK on cool days but not so good on warm days, I think! Because I know for a fact that my mechanic had looked it up and had found 32 oz and that is what he put in.

 

My hunch is that being 2oz low you probably wouldn't be able to notice it. I think you've got something else going on, but if it's your buddy might as well add 2 more oz and see if it makes any difference