My AC is not putting out cold air and I am quite certain it simply needs charging. My mechanic quoted $150 to do this and I know he would do a quality job.....full evacuation, flush, pressure test and die check, and then add refrigerant and test output. I believe I do not have a leak in the system and am wondering should I simply (and properly) just add refrigerant and monitor performance. Or should I pay the mechanic to peform the proper tasks?....it's a '99 and may deserve a professional inspection and flushing. Further, I would appreciate if anyone can share a thorough "how-to" procedure for this task. Or better yet, can it be appended to the link in the tech info page for the same topic. Thank you.

Pat
99 XLT, SCAB, 3.0L, M5OD, 4x4 w/ Off-road, 65k miles

 

If it didn't have leak it wouldn't need charging. At this point you are guessing as to what is happening. The first thing to check is does the compressor clutch engage if does does it cycle on and off real quick. If the clutch doesn't engage then you need to insure that electrical side of this is ok before continuing. Fuses relays pressure switch. If it cycles on and off real quick at idle then yes you are probably low on refrigerant. Just putting on refrigerant may work may not if something else is wrong it can be dangerous. I believe if you don't have the gauges to check the systems pressures you probably ought to pay the man to fix your air.

 

i agree with the above poster pay the money and ask them to put dye in so if there is a leak and there is if youre low so they can pinpoint it alot of the time its a silly O ring

 

Yes, it does engage and frequently. I should have included this information in my initial post and thus the basis for my suspicion that it is low on refrigerant. I take your point about need for charging implies leaks, but I believe it is also normal for some refrigerant to simply pass by seals over time. And yes, I do not have the proper guages, and thus why I'm leaning to let the pros service it. Except, the refill kits do include a guage to aid to control how much to inject.

 

i had the same problem last year about august. 99 ranger . Bought the can with the guage at autozone and it said my freon level was good. I brought it to my mechanic buddy who did what you said was gonna happen to yours and turns out the guage on the can was bad and i was indeed low. He charged it and it ran fine but he vacuumed the system too and to me it was worth it.... i dont remember him charging me more than $90 tho

 

Good feedback. Thanks Bob.

 

Yeah, A/C is supposed to be a sealed system. My 89 shadow still had R12 in it, and my parents 98 minivan is still charged. R134a isnt something that supposed to leak out even naturally. With that being said My 88 F150 has the same problem. When I got it 2 years ago the system was discharged. I added a couple cans to it and it worked good for the past 2 years. I just put in another can yesterday because it was low again. One of these days when i get the time or money i'll find the leak and fix it.

If you just want to add its pretty simple. Buy a kit from the parts store, or wal mart or wherever. Get one where you can hook the gauge up to multiple cans, because some stores sell them where the gauge is permanantly attached to the can. Then you pop your hood. There is a black canister the size of a can of tennis ***** right next to your blower motor. Coming off of this on the top there should be a line. There is a black cap covering up a schrader valve. Pull the cap off, hook up the quick connect from the can/gauge, and let it flow in (you must have the car on with the a/c on too.

 

Just a little advice on vacuuming... you usually don't need to do it.

The reason we vacuum the A/C systems on this is to remove moisture (not to suck all the air out, as most people think. That would be impossible anyway.. and it's not necessary.) Just as pressurizing the cooling system raises the boiling point.. well vacuuming the A/C system lowers it. If you get enough vacuum, the moisture will evaporate at room temperature.

The only way moisture would get into the system is if it sat 'open' (i.e. a component being removed), or all the freon leaked out, and the system sat empty for a long time. Any charge at all, even a slight one, will prevent moisture from entering the system.

The moisture can turn into ice, which can clog up orifice tubes, expansion valve... screw up the pressure switch.. etc.. etc...

Also R134a is a lot more tolerant to moisture than R12 was.. so sometimes even a quick part replacement may not require vacuuming (especially on a non-humid day).

If you don't feel you have a leak large enough to warrant repairs, just charge her up. Do it a half can at a time, with a thermometer in the middle vent, A/C high, windows closed while idling. Once the thermometer stops going down (or maybe even climb back up just a tad) then you're starting to overcharge it.

While the pressure gauges make a great diagnostic tool, they aren't so great anymore for determining charge level, as every car has it's own different "sweet spot" as far as pressures go.. especially since the R134a came out.

Good luck.

 

Well - there's a couple of posts worth saving to a Word doc (as I just did!)...

Thanks, fellas! Always wondered what I'd do "if" the A/C ever needed a shot in the arm.

Cool!

(pun )

Bob

 

Also, have you checked the blend door? Have you checked to see if it blows cold air when set to Max A/C?

 

Thanks MazdaRangerGuy. I'm still undecided which way I want to go on this. Yes, the blend door operates properly....I can hear it move when switching to Max AC....but no cold air is available.

Can you confirm which connection to use to add refreigerant. I believe it is #2...Low pressure on the accumulator.

[Schematic courtesy of Rockledge:
https://www.ford-trucks.com/forums/1...arging-ac.html]



<FIELDSET class=fieldset><LEGEND>Attached Images</LEGEND>




</FIELDSET>

 

Pat, the #2 (low side) is the correct port to use to add refrigerant.

Disconnecting the cycling switch and jumpering the two pins in the harness connector will cause the A/C condensor to run consistently. This helps to draw the refrigerant into the system. Keeping the can(s) warm while you add the refrigerant also helps.

 

You should always pull a vaccum on the system if it has been opened. for the following reasons
1. You have to get rid of the non compressibles ie air if you don't the system will not work right air can not be compressed and returned to a liquid state at the pressues these systems work at.
2. Moisture is not tolerated by refrigerants very well r134a is a bit more tolorant than r-12 but the combination of mositure and r134a creates a corrosive mixture that will eat the aluminum parts of the system from the inside out.
3. The vaccum pump i use will pull as near a perfect vacuum as is possible at the altitude that I live and work at 29.7 inches of mercury. That means there is not air in the system and the longer you pull that level of vaccum the more moisture you remove.

 

Just added 2 cans a couple of days ago,using the gauge that came with the kit.Then I put my "real" gauges on it and everything seems fine.

 

Yes wtroger, you make a couple good points, but I also see some flaws.

Air CAN be compressed.. it's liquids which cannot. Yes it's a good idea to remove as much moisture as possible with vacuum, but that's exactly why you do so.. it's impossible to remove all of the air without collapsing every hose and line in the system.

And I agree.. if the system is opened up it should sit on a good strong vacuum for a long while, and I follow that practice.. but if the system has even a slight charge to it and has not been opened, then it typically isn't necessary.

I have done a couple of "field services" on A/C systems where a vacuum pump was not available.. just a quick component change and a charge, and they have turned out fine, but then again I take precautions to not leave the system open any longer than necessary, and covering any openings that do happen to be open to prevent accumulator contamination. Now I'm not saying that's good to do, but if your theory held water, then the "non compressible air" in the system would have practically destroyed the compressor, yet somehow that failed to happen.