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Old 08-21-2002, 08:17 PM   #1
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can't get freon into the ac system

Ok, I replaced my compressor, accumulator, and orifice tube, and I was trying unsuccessfully this afternoon to charge the system. I hooked up a can of R134a (I know, its called suva, not freon, but what the hell), and only half of it would go in. I then started the car and turned on the compressor, but it would not suck anything in. I turned off the car after about a minute, cause i got scared of running it with such low a charge. It was cycling every two seconds or so. Anyway, I am probably going to end up taking it to get charged somewhere if I can't figure out what I did wrong. Anyone have any suggestions?
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Old 08-21-2002, 08:22 PM   #2
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To charge an AC system it's supposed to be sucked down into a vacuum first. You don't want air and moisture inside the AC system.
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Old 08-21-2002, 08:38 PM   #3
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Have you converted your car over to r134??? Unless I am mistaken you can't just put r134 in a car that is made for freon. You have to convert the system over. YOu can't charge it with freon, because your have to be a certified ac tech to get your hands on some freon.
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Old 08-21-2002, 09:34 PM   #4
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Quote:
Originally posted by jfox55
Have you converted your car over to r134??? Unless I am mistaken you can't just put r134 in a car that is made for freon. You have to convert the system over. YOu can't charge it with freon, because your have to be a certified ac tech to get your hands on some freon.
system is open and discharged anyways due to compressor replacement.

for info on the r134a to r12 conversion, see this document:

http://www.iroczone.com/projac01.html
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Old 08-21-2002, 10:32 PM   #5
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I realize it is best to hook up a vaccum pump to the system before charging, but I need to use the car soon, and with the ac off, the engine temp skyrockets cause the fan won't come on. So for the moment, I was just going to get it working.

I am converting to R134a. I've replaced the compressor, orifice tube, accumulator, hoses from compressor to condenser and from accumulator to compressor (had a leak). I used PAG oil which is required unless you flush the system (GM put out a service bulletin where they recommended not to flush to avoid compatibility problems with the R134a and what is used to flush which is R-11 i believe).

The only thing I can see that I didn't do right was vaccum the system, but supposedly, that would just increase cooling performance. Either way, I have the impression that the system should be able to draw in the gas. Am I mistaken?
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Old 08-22-2002, 01:43 AM   #6
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There is a wire that pluggs into the accumulator. (I think that's what it's called, it's the silver thingie that gets wet when you turn the AC on. heh)

Anyways, it's near the top, near the passenger's side fender. You have to pinch it from either side to be able to unplug it. When you do, there's a screw between the two prongs of the connection. That screw determines how long the AC cycles on and off by allowing you to set the pressure that the compressor pumps to. Turn that until it compresses to about 30psi and then lets off. (If you bought a kit, it should have come with a gauge. As long as it's within the green, it's fine.) You'll have to plug the connector back in before it will start cycling, though.

Another thing to consider -- If you leave the above mentioned connector .. disconnected heheh you'll have turned the AC controls into a nice little fan switch. When you turn it to the AC, the electric fan will come on but the compressor won't.
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Old 08-22-2002, 06:55 AM   #7
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before you try to charge it you need to get it sucked down. it doesn't matter if you need the car real soon or not, you have to do that before you charge the system. if you need both fans to run hard wire it to get you by then switch it back.
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Old 08-22-2002, 01:40 PM   #8
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I've just got to say my piece...

There are right and wrong ways of converting from R12 to 134A, but there are also many shortcuts. A R12 system in good condition that has been evacuated of all freon can be recharched with 80% of its capacity of 134A and the appropriate amount of oil. This works on all american compressors. Note: If your system leaked out all its R12, then you first have to find and fix the leak; Drawing down a vaccum is always a good idea; Changing the accumulater(dryer/filter) is always a good idea.

To charge with 134A from a can you must turn the AC on and wait patiently for the system to draw in the charge. Inverting the can will speed up the process, but can be dangerous if the system is nearly full. Note: 134A works at 20% higher pressures than R12 and if your hoses are not up to par they could burst; Running the AC with a partial charge is not bad, but the compressor may cycle continuously.

Finally, you don't absolutely have to draw down a vaccum. It does increase your cooling performance, but it will work well or even good with out doing it. Don't expect a conversion to ever work as good as R12. With practice even old 70's cars that have long ago lost thier charge can be quickly converted to 134A for very cheap.
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Old 08-22-2002, 03:06 PM   #9
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You must evacuate (vacuum) the system before charging.
No exceptions.
The evacuation process makes the trapped moisture boil and the steam is sucked out by the pump.
Moisture left in system will freeze at the orfice tube and block freon (or 134A) flow. Blockage will kill a compressor real quick.

When the system is evacuated, it makes room for the freon.
Without evacuating, the air is taking up space and all the freon simply won't fit.

With the system evacuated, you should be able to install abt 1 1/2 cans before having to start the eng. The rest will be sucked in once the compressor is running.

Also after pulling the system down to 29" for at least an hour, you should shut off the valves to isolate system and see there's a leak.

You have spent some hard earned greenbacks on it with the new parts, beg, borrow,rent a vacuum pump and finish the job right

Any short-cuts you take with your A/C will come back and bite you in the a$$.

Check out aircondition.com..
They have a message board thats full of good A/C info.
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Old 08-22-2002, 08:40 PM   #10
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Finding a leak by sucking the system down into a vacuum can be difficult. I charge the system with nitrogen then listen for leaks and or soap test fittings and hoses.

Those hard to find leaks are found with UV dye.

It's nice to work in a shop that's well equiped.
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Old 08-22-2002, 10:14 PM   #11
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Thanks alot guys. I'm gonna go ahead and get a vacuum pulled on the system, and then try to charge it up. Hopefully I have time tomorrow.
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Old 08-22-2002, 10:34 PM   #12
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Have you ever filled a system with out evacuating it?

I've done it both ways, and honestly haven't noticed any difference. All the reasons ZZ28 gave for evacuating a system are good reasons...but it will work without doing it. My Bird--going fours years with 134A and I never did draw out all the killer moisture and such. Same with a '79 Chrysler, '91 S-10, '89 Suburban, '79 Mustang, and more. All these cars still blow cold--no evacuation. If it works, then...
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Old 08-23-2002, 02:23 AM   #13
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AdmiralNahohkta, did your conversions involve breaking system open (i.e. parts replacement)?

If you simply vented the systems and didn't allow outside air into the system, that would explain why you haven't seen any moisture related issues.

I've been to a few different A/C schools, and they always say to replace the dryer and evacuate any systems that have been opened to atmosphere.
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Old 08-23-2002, 11:55 AM   #14
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Somebody's missing something obvious here:

WHY WON'T IT TAKE THE REFRIGERANT????? That was the original question and it's a good one.

I suspect that you only THINK the refrigerant has not entered the system. If you're used to doing "home recharges" on R-12 then you'll probably need to readjust your thinking on 134. In short: THE CAN WEIGHS ALL MOST AS MUCH DISCHARGED AS IT DOES FULL. This one screwed me up the first time I did a 134 conversion. I waited almost 20 minutes with the hose connected and the damned can still weighed a ton! A helpuful A/C tech clued me in and let me know that I had done it right and that's just the way it works. If your compressor is cycling on and off AT ALL, there is some refrigerant in the system.

I have since done 3 system conversions to 134- successfully, I may add. I have not drawn any of them down under vacuum before doing the conversion and it didn't seem to cause any problems. However, I did not crack any of the systems open to replace any parts.

Another observation about 134: Converted systems usually leak. They run at slightly higher pressures AND the size of the molecules is smaller, meaning it will leak out of places quickly that R12 would not leak. Expect to have to throw a can in from time to time to bump it back up on most older/original R12 systems. By the time you see oily stuff at a fitting or seal the 134 is LONG GONE. Again, just one of those things that is different from R12.
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Old 08-23-2002, 12:58 PM   #15
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The first can I tried to put in I lost instantly cause I had a leak in a hose. I heard the leak and found it, it was not at a fitting, the gas was leaking at a spot where the metal tubing meets the rubber part. I could feel the gas when I put my hand over the hose. I replaced the hose, and put in new orings again even though I had just put in new ones with the compressor and acuumulator. I made sure I oiled them well, and then doublechecked all the fittings to make sure they were tight.

I was too lazy to throw out the first can, and I just left it lying around with all my tools in a corner. When the second can wouldn't go in, I picked up the empty one and while there wasn't a huge difference in weight, it was significant enough to be noticeable. After I got tired of nothing entering the system, I decided it was doing no good to leave it there, and I disconnected the fitting at the service port. There was gas leaking out of the can for a long a$$ time. I doubt even half of the can got inside the system.

This is my first attempt at any A/C work. I've never worked with R12 either, so I am pretty lost as to why this happened.
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Old 08-25-2002, 11:37 AM   #16
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Even after the can has emptied all refrigerant into the system, when you disconnect it the can will leak "for a long-a$$ time" like you say. It'll also get cold as he11 and freeze your fingers right onto it if you don't watch out!

Basically, if you connect the can up, open the valve and the can gets cold after a few minutes, it's done it's job and emptied the 134 into the system. When you disconnect it will spew out vapors and maybe a little oil for a few more minutes and get REALLY REALLY cold. It threw me off the first time, too, but that's how it works.

BTW- after discharging the can into the system it's a good time to use the spray from the discharged can to freeze ants solid to the ground! Cryogenic freeze-dreed ants! Not that I'd ever try anything like that.
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Old 08-25-2002, 12:08 PM   #17
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Alot of the cheap charging hoses they sell these days have real problems opening the schrader valve on the A/C... try getting a set of gauges, which will have a much better hose. They'll also give you enough information to enable you to put the correct amount of Freon in the system. You should be able to find a set at Johnstone or Grainger for not too much.

Definitely pull a vauum on it. It's necessary, you will have trouble with it if you don't. People who livve in extremely dry climates, or who work on their A/C when it's cold out and there's far less moisture dissolved in the air, can sometimes get away without doing it, but the system will still always work better and last longer if evacuated.

I don't claim to be an expert, but my wife did work at Ig-Lo Products (the place where they can the Freon) for 20 years, so I've had access to quite a bit of info on the subject; and I've repaired countless A/C systems over the years myself. I have always been unable to get one to work right reliably without evacuating it, if it was broken open and allowed to get outside air in it.
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Old 08-25-2002, 01:31 PM   #18
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I didn't read all the posts but I can say this for sure, replacing all those parts and not evacuating the system with a vacuum pump is like wiping your *** with used toilet paper.

Why won't it take the charge? Because the low pressure switch turns the compressor off at around 20psi, you need to open the can and add vapor, the comp will kick on until it pulls it back down to under 20psi, then it will kick back off. The compressor will run longer each time because it's sucking more refrigerant in every time it comes on. You can invert the can and add liquid to speed up the process but don't let the suction line to the compressor get frosted. You could also unplug the low pressure switch and jump it with a wire to speed up the charging process.
PS if you're not going to do things right expect problems like this.
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Old 08-27-2002, 09:49 AM   #19
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If you don't pull a vacuum on the system, you may have to jump the low pressure switch on the accumulator to get the system to suck the refrigerant in. I did.

If you're just putting refrigerant in to keep the system sort of working, and don't care how well it performs, evacuation isn't required... especially if you plan on discharging and evacuating later (like I did).
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Old 08-27-2002, 11:39 AM   #20
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Quote:

If you're just putting refrigerant in to keep the system sort of working, and don't care how well it performs, evacuation isn't required... especially if you plan on discharging and evacuating later (like I did). [/b]
There, I've been seconded! And yes, I did open up the system and replace the accumulater in the hot, sticky, humid air of Tennissee.

I'm going for a drive now, and I'll let the cold air of my non evacuated AC waft over me...
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Old 08-27-2002, 12:52 PM   #21
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I agree with the admiral, there are right and wrong ways for doing every thing. The wrong way usually ends up being most peoples ways because we don't own $10,000 in tools. What most people have access to is a charging hose and a can of refriderant. I use stuff that you can add to either freon or 134. There are several that say they are compatable, but I've heard mixed results. To charge up your ac, you need to do the following: 1) start the car and turn the ac and the blower fan on max. I believe the cooling fan is supposed to also come on. if yours doesn't, you may have additional problems. Verify. 2) hitch up your 134 or compatable, invert and slowly open and add refridrant. your compressor pump should start cycling and you should start to feel cold air in the car. 3) keep adding slow amounts of freon until the air is blowing around 40 F.

be carefull not to overcharge!! = to much pressure.

if you are having problems getting the refridgerant in, check the condition of your valves/hoses and make sure everything is screwed down tight. another trick is to run a hose of cold water over the condensor (thing in front of the radiator) to help make more room for the 134.

many vehicles also have a little sticker on the dryer that changes colors as it gets colder. starts black and then turns blue to green or green to blue. i forget which. either way, if you don't have such a sticker, i believe you can purchase one and stick it on top of your dryer.
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Old 08-27-2002, 12:57 PM   #22
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Here's the way I always handle my AC stuff:

#1, if I'm not going to use it, I make sure there's oil in the system and unplug the low pressure switch. If the clutch doesn't engage, it won't do damage--it's just an idler pulley at that point.

#2, If I plan on doing the car RIGHT later, I won't bother to evacuate it. Waste of time and money. When I took the car to Ohio I just wanted it to blow something colder than outside. 60* vent in 80* weather was fine for that. It all leaked out in two weeks anyway. Many times if the system isn't evacuated it won't take enough refrigerant to kick the A/C on unless you've adjusted the cut-off pressure on the low pressure switch (again, R134A only). Just jump the switch with a wire until it pulls enough refrigerant in to cycle properly.

#3, If I want maximum cooling performance, I swap the orifice tube (when converting to R134A only), evacuate the system, and charge.
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Old 08-28-2002, 01:40 PM   #23
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I jsut did another one last night. THought I'd pass along some more expereince......

RB is absolutely right- some of the cheap parts store hoses have a hard time pushing the pin on the schrader valve to open it and admit coolant. I just did my brother's 134-converted 85 Z-28. Had this problem exactly. It took over 20 minutes(!!!!) to put one can in BUT IT DID GO IN. Be patient. Might take some time. I suspect that sometimes the change-over valves they supply to convert to 134 are not of the highest quality.

Also, keep the can somewhere it can be warmed while charging the system. Like close to an exhaust manifold (not touching!) or in the hot air stream off the rad fan. The first bit of the can goes in real quick but then it slows way down as the contents of the can get cold from the decompression. Heating slightly will help speed the process slightly. Again, have patience.

As for the evacualtion issue.... once again, I did this one without replacing stuff and opening the system to outsde air so I didn't evacuate. No problems to report but...... I would say I agree with the general opinion that if you want to do it totally right, evacuate it. If you just want to get it working, forget it.
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