What's wrong with the A/C?

Derek The Great · Jun 5, 2008

Whats goin on?
So i charged up my A/C (134a) in my ranger with one 12 ounce can last saturday. so far this past week i havent had to use it much but today was a doozie here in MI. Even after 45 minutes of driving it didnt get colder than like luke warm. It took the humidity out of the air, which was about it. So i decided to add another 12 ounce can, and got the same result if not worse. A/C compressor works, but doesnt cycle, its just constantly working. Yesterday though, it was around 75 degrees and raining, the a/c was pretty dam cold then. At one point i think the evaporator froze, because the air flow from the vents slowed down? Also, today i noticed a strange noise when i accelerate like a whooshing or whine its hard to describe. The noise is similar to the noise you get when you start your car and immediately drive off.. My buddie tells me i might have a crappy evaporator, i think i have an issue with the compressor, i mean hell i added 24 ounces of 134a and the air is still warm... What do you guys think?
Thanks!

Sasquatch_Ryda · Jun 6, 2008

If you are having to add refrigerant, you have a leak. You need to fix the leak first off, as its illegal to vent refrigerant to the atmosphere.

Earl43P · Jun 6, 2008

R-134a is a tricky refrigerant. There is a very narrow band for proper servicing. If you put in "just a little too much", it acts just like having too little (doesn't cool). You can't simply "add a can" and expect to get lucky.

Since you CLEARLY don't know what you are doing, I recommend a professional servicing.

An alternative is to open the valve while you keep the engine at 2000 rpms. Monitor the temperature coming out of the center vent, fan on med speed. At the first hint that the air is not getting any colder, close the valve and drive it. Continue to monitor the thermometer. When you drive, it should get about 4-6 degrees colder than it did sitting still. If you get that, quit. If you get 45-50 degree air out of the vent, quit.

More isn't always better, lol. And you should fix the leak FIRST.

The whooshing sound is your fan clutch doing its job.

At this point, DO NOT ADD ANY MORE REFRIGERANT. You could blow the pressure relief valve. You really need to hook a set of guages to the system.

Derek The Great · Jun 8, 2008

Yeah i really dont kno what im doin. I know about a/c systems and their components, just not how to diagnose whats goin on. As it stands today the dam a/c just acts as a dehumidifer, and will cool the air down about 8 degrees cooler than ambient temp.. I dont like the idea of venting crap into the atmoshpere but i dont like the idea of a 1500 dollar repari bill either.. Again, my buddie thinks its leakin out at the evaporator, and that over time PAG oil has coated the evaporator. Because of that the air flowin past it doesnt get cool enough. Well if thats the case then the evaporator is inside the engine compartment and shouldnt be too hard to do, but i dont have a 134a recovery system so thats where my repair stops.... How expensive do u think it would be to throw the thing at a dealer??
thanks,
Derek

RobbieD · Jun 8, 2008

Call around every shop in the phone book and get quotes for just evacuating the R134 from the system (into a legal recovery machine). From that point, if you're game, you can replace the evaporator (and receiver/dryer) and charge the system yourself. Just throwing an "option" thought your way.

Earl43P · Jun 8, 2008

I agree on the replace the components yourself. Although, if it is dehumidifying, it may be "close" to the proper servicing level. You could try the thermometer in the outlet duct method and if adding more refrigerant makes it colder, find the sweet spot. You DO RISK overpressurizing it and blowing the overpressure valve. Then you need a new compressor. Your call.

But you really need a shop to evacuate it (with a vaccum pump), you should also replace the filter dryer, and the shop should service it and add the appropriate amount of oil for the component you replaced.

You should also replace the orifice tube, simply because it is cheap and collects debris.

Frankly, if you can see the oil on the leaking component (evaporator), adding more r-134a isn't the solution.

MAKG · Jun 9, 2008

It's only necessary to replace the accumulator/drier and orifice tube if the system has been open to the air. But it does make a nice diagnostic.

Derek The Great · Jun 9, 2008

Thanks for the advice fellas, I think im gonna look into havin the system evacuated like Robbie suggested, and replace the parts mentioned. quick question, near the compressor on the highside there is like a small black drum (just above the power steering pump) which leads into the condensor, what is that? I noticed like oil around where the rubber hose meets the metal drum, i hope that isnt the over pressure valve..

RobbieD · Jun 9, 2008

The "can", or drum, on the high line is an inline muffler, to reduce noise made by the AC system. Look at it good, and if you think it's leaking, it would be best to just replace that hose, too, while you've got the system apart doing the other work.

Derek The Great · Jun 15, 2008

Ok so saturday i finally had time to look at the truck.. I had a dealership charge the A/C system to the proper pressure, turns out i had 3.7 lbs when it should have been 1.73 lbs of refrigerant. The A/C got a lil cooler, 59 degrees outa the vents. Before i started tearin things apart i figured id check the basics. Well there was no change when selecting panel, Max A/C or off. Turns out a vacume line was crammed up under the dash. Then i noticed there was a ton of dead leaves and crap between the radiator and condensor. So i had to take the fan off to be able to get the radiator outa the way so i could clear the crap. Well i checked the temp at the vents afterwords in max a/c and im gettin 45 degrees (in the shade). Not sure if this is the coldest it could get but hey its cold enough so my back doesnt stick to the seat any more :headbang:

RobbieD · Jun 15, 2008

You made some good progress there. I hope that what you found was all there was to it.

fordwheelinman · Jun 15, 2008

I hope you learned your lesson. Without proper knowledge and equipment, it is IMPOSSIBLE to PROPERLY diagnose an a/c system. I say it every year and yet someone somewhere refuses to listen, if you dont have the tools, knowledge, and experience to know what your doing, TAKE IT TO A SHOP!!!

Derek The Great · Jun 16, 2008

Geez... so nice of you to post. Ok so im not an experienced HVAC guy but you learn through experience. The only tool i didnt have is the pag oil reclaimer majiger so i took it to the shop to have them charge it to the right level, i didnt break anything by doing what i did. I took care of the rest. ---Three weeks ago i had to bleed my clutch b/c the shop i took it to didn't kno what they were doin, so thats not always true.

MAKG · Jun 16, 2008

To be completely fair, installing a clutch is a FAR less complex operation than diagnosing and repairing air conditioning. Having done both. Just because they cost the same order of magnitude does not mean they are equivalent.

You put less-well-trained technicians on the clutch. And YOU can do better than them; it's not hard to guess what's going on with very basic understanding of the system. And you can redneck all of the tools short of a socket set.

On the other hand, it's relatively hard to do anything correctly with just basic understanding of air conditioning. And most random guys don't even have that. And you need the CORRECT tools in several cases; rednecking the vacuum pump or guessing at high side pressures, for instance, simply does not work.

Evan · Jun 16, 2008

MAKG said:
To be completely fair, installing a clutch is a FAR less complex operation than diagnosing and repairing air conditioning. Having done both. Just because they cost the same order of magnitude does not mean they are equivalent.

You put less-well-trained technicians on the clutch. And YOU can do better than them; it's not hard to guess what's going on with very basic understanding of the system. And you can redneck all of the tools short of a socket set.

On the other hand, it's relatively hard to do anything correctly with just basic understanding of air conditioning. And most random guys don't even have that. And you need the CORRECT tools in several cases; rednecking the vacuum pump or guessing at high side pressures, for instance, simply does not work.

+1 MAKG.

Most of you know that I'm pretty good at working on RBVs, but I won't touch an AC system, and I even understand how they work.

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