2004 F150 Lariat, 4x4, 5.4 3V:

I just finished recharging my AC after I had to remove that low-side hose to get my passenger valve cover back on. I didn't do this when I took the valve cover off, but I decided not to chance tearing up my new valve cover seal, so off with the hose! Anyhow.. I'm still learning how to do the A/C systems. I have all the gear, vac pump, gauges, etc.

Question: What's the average temperature should you be seeing at the vent with A/C on max?
With my ambient temperature at 75 degrees, I'm showing 58.5 degrees at my center vent using my digital temperature probe. Seems pretty good to me I think? Or did I break something?

Thanks,

 

Usually mid to high 40's especially with your weather. Maybe 50's if in the 90's or 100's. Post a video of your high and low gauges with the compressor running if possible

 

Yeah if it's only 75 out you should be able to freeze yourself out with 40s at the vent.

 

Crap. Wonder what I did wrong. I'm kinda wondering if my pump might be going. 180k miles all original and probably the first time in its life it's ever been discharged (well.. maybe 2nd.. someone did the phasers before I bought it). I was always told a person should replace that drier any time you crack the system open? I didn't do that this time, but I definitely will if I have to discharge/recharge again.

The low side (running) is 40-45psi and I think the high side was 170-ish? I wasn't paying too close attention to that side . I'll toss the gauges back on soon as I get a chance and post a pic. Gauges were steady.

Another question of a million: Are there different types of 134a Freon? In other words - is one COLDER or better than the other? I always wondered as you sometimes see cans labeled 'super-duper 134', or 'buy out brand x - it'll freeze the ***** off a well digger".. lol.


Thanks for your response guys!

 

First point; 134a is a chemical compound and it’s the same everywhere. But it can also be sold with refrigeration oil included, and some are available with a dye added for detecting leaks. In fact, the original refrigerant Ford used in our trucks included a green-yellow dye which you probably saw when you loosened the first fitting. Other than those differences, the manufacturers take liberties to over sell their products that are not based in fact. So check the fine print to see if there’s anything in the can besides the 134a.

To your concern about whether your system is working properly; a 15 degree temperature drop isn’t bad. Remember that your refrigerant does two things, cools the air and as a result of that temp drop, removes moisture. Due to the latent heat, it takes more power to remove the moisture than to cool the air. So be mindful of the humidity and dew point while taking your temp checks.

I would check a couple things before I ring the alarm. Our trucks don’t have a sight glass to check if there is a sufficient charge. The proper amount of charge is 37 oz. Did you add 37 oz’s of 134a? If not, you may have an insufficient charge and that will limit how cold it gets. Is the compressor cycling on and off? That might also indicate insufficient charge. Adding too much refrigerant is bad too so don’t add more unless you know how much is already in there.

From the Ford shop manual, at 75 degree ambient temp the discharge pressure can be anywhere between 140 - 240 psi, suct pressure anywhere between 27 - 48 psi. System pressure when off and equalized at 75 degrees should be 60-80 psi.

Replacing the accumulator/dryer is generally only done if the compressor fails or if there’s evidence of contamination in the system. If you don’t see that, and from your OP it doesn’t sound like it, you should be good.

I would kill for a 75 degree ambient temp right now...