Cage issue

[motoman]

Good, XSokie so far gots' it under control and headed the right direction. This one could a bit difficult not being there. Give him specifics and details if needed, and YES in this area super cleanliness is essential for expansion valve etc. New dryer may or may not be in order too. A/C systems can be a bit tricky at times to solve issues, alot of variables. Lead-on XSokie as this could easily go beyond my ability to diagnose, and there expensive enough to fix without adding any unnecessary expense.

[dbeardslee]

It sounds like it may be overcharged or full of air from someone trying to "add " refrigerant.

I think I even know who that someone is . I'm pretty sure I can evacuate and recharge it, and I've got manifold gauges and a vacuum pump (acquired after the freon incident), but it's one of those little ones that you connect to an air compressor. To tell the truth, I'd rather spend the money on a better vacuum pump and learn how to do it so the next time I'll be prepared. Here's the way I understand it - If it holds the vacuum for 30 minutes, then you don't have any leaks. Purge the lines of air, and add freon slowly through the low pressure side, with the can 'up' so as to put gas into the system rather than liquid. As far as I know you keep adding the freon until it's in the correct operating range, or are systems rated by how much they hold?

[motoman]

Both come into play along with atmospheric pressure at the time. Sounds like you may have it under control, least you hope it goes your way without alot of expense. Just watch if that high side pressure starts spiking way high(and don't remember what the safe rule of thumb level is). Have seen bad things happen concerning that high side, usually just before compressor decides to sieze.......I'll be quiet now.

[dbeardslee]

I hear you, brother. I'll definitely pay attention to the red gauge. After my botched freon adding last year, I bought the haynes automotive heating and air conditioning book, and read it a couple times. I figure I know just enough to be really dangerous . Funny thing is, I've added freon to a lot of cars in the past and never had it backfire on me. This stuff had some compressor oil in with it too, but I don't know if that made much difference (are you sensing a pattern with me and additives ). I also know I didn't purge the line before I put it in. I'm going to try doing it by the book (with all suggestions appreciated, cause the book's been known to lie), and hopefully I won't blow anything up.

[DGXSER]

Depending on the size pump you buy, you want to be careful how long you pump it down for. The system is not 100% air tight down to any vacuum you choose. I know the pressures for industrial and commercial building systems but not for automotive. Your book should tell you a vacuum to pull on the system. I would let it sit at that vacuum for 30 minutes and see that it holds for that long.

Then, hook your center line of your gage set to the freon charge, and purge the line of air before you charge the system. Hook the low sie fo the gages to the low side of the system, and let then open the freon valve to charge the system. Let the compressor pull the charge into the system till you read the correct pressure for the system and the freon in use.

[dbeardslee]

My ISP has evidently been acting up - haven\'t been able to get on the site for several days. I bought a little HF vacuum pump, and without too much trouble I was able to evacuate and recharge the system. Everything I was seeing on how much vacuum is required suggested 29 inches was the number. One source stated that 29.72 inches is the point where the water comes out, but who knows. I just put the pump on it, drew the vacuum down for a few minutes, closed the valves and watched the gauges. There was no vacuum loss after a few minutes, so I turned the pump back on and let it do it\'s thing for 30 minutes. I put freon and about an ounce and a half of oil in, adding the freon until the gauges were reading where they should be. The compressor is no longer kicking on and off, and it\'s blowing some pretty frosty air. Thanks for the help - looks like you guys are two for two .

[b.walker5]

You seem to have this sorted already, but..

The best indicator of system vacuum is an absolute pressure guage but it's not going to tell you how much moisture remains. There is NO set time limit for evac, longer is better but if you've got an essentially dry system before you begin then holding max vac for 5 minutes may be enough. Since, without the right equipment, theres no way of knowing how much moisture a system has in it theres no set time to evacuate. If you can find one then use a CPS, or other brand, digital pressure guage that measures in microns. For a new system, with a new dryer, aim for 200 microns for at least 10 minutes and you'll be fine. For a repaired system without a new dryer, aim for 500 microns for at least 30 minutes. If your dryer has a sight glass with a coloured moisture indicator you can keep an eye on this while on the vac pump, to get an idea. (You should NEVER open a system without replacing the dryer). The refrigerant charge should be weighed in as a liquid with a good set of scales, unless you have one of those little disposable cans with the right amount from the dealer. (my gas is in 30lb jugs) To properly evaluate the system after charging, connect your manifold to both the high and low side and run the system on full cool with the doors open. Start engine and select medium fan speed (not low or fast). Wind up your idle to around 2000 rpm and start your AC. Take notice of the low side (LP) guage. Assuming 134a refrigerant and depending on the ambient temp, you should see the guage drop to around 2 bar (30lb). The high side should be around 8 to 9 bar (120 to 130 psi) but could easily climb to 10bar or higher if the condensor coil is obstructed or the fan isnt working properly. A thermometer in the middle air duct in the dash should give you readings of down to 2 degrees (C) in a good working system.

I dont wish to detract from the knowledge that obviously exists on this site, but refrigeration/air conditioning is a precise science with many, many variables and unless one is fully trained to understand the characteristics of refrigerants under different and vairable conditions then IMHO repair is best left to proffessionals. You are dealing with pressurised gasses than can be dangerous if incorrectly handled.

On a side note someone mentioned earlier that pepper added to a water system can stop leaks. Dont scoff.. As crazy as that sounds it works. I am in the HVAC/R trade and we deal with many large commercial and industrial boiler systems. Pepper is frequently used to stop leaks, and can remain effective for many years. We use it by the pound but a smaller car system would require one of those 2 or 3 ounce table contaniers found in supermarkets. Personally I would never use Bars Leak, it's very well known over here to block radiators. When i'm flushing my 'rod' I drain and refill with fresh water and add 2 tablespoons of washing soda. I usually go for a drive for a couple of hours and then drain it out again. I then disconnect the radiator hoses, and the engine thermostat. Starting with the block, i attach the garden hose to the thermostat housing and let it run for 15 minutes or so, and then I do the radiator with the same method. Then reattach the hoses and thermostat and refill with glycol and water. But then thats in a cast iron 350 so I'm not worried about the caustic eating alloy heads etc.

[dbeardslee]

Something I forgot to mention

XSokie\'s idea of back flushing the heater core was probably the tip of the week - so simple yet so effective. I pulled the heater hoses, and put a garden hose in the upper such that the flow was reversed and hit the trigger. First I saw a slow stream of some nasty brown juice come out of the lower hose, it sputtered and spit a couple times and apparently blew the last of that d**n bars leak out. I flushed it forwards and back several times until all it only flowed clean water. Hooked the hoses back up, put a new 195 degree thermostat back in and burped the air out of the system. Ever get that feeling like your heater was about to melt your gym shoes? Well it\'s not quite that hot, but it\'s close enough for government work . Thanks, Okie - you saved me buying a heater core.

Here\'s how I did the a/c recharge. I actually did it a couple times due to the lack of info on the jeeps system. Everything I was seeing said to look for a pressure of 30 psi on the low side, and 2.2-2.5 times ambient temp on the high side. What I got on the first attempt was around 30 on the low side, and around 225 on the high side at 80 degrees ambient temp. The high side looked too high, so I decided to start over. This time I drew a little freon in the system with the vacuum (engine off), closed the valves, started the motor and let it reach full operating temp. I then opened the low side and allowed it to take the rest of the 12 oz can. At this point I closed the valves, disconnected the empty can, attached a fresh and purged the line but didn\'t open the low side valve. I raised the idle and watched the gauges - the high side pumped up and the low side dropped below 20 psi and the compressor shut off. I opened the low side valve and watched through the site glass as a bit more freon went into the system. Raised the idle again, and watched the gauges. I kept adding freon until it would come down close to 20 psi with the idle raised slightly and steady (I\'m guessing 1.5-2k rpms). This particular system is supposed to take 1.25 pounds (20 oz) of freon, and 1 ounce of oil when evacuating and recharging. What was left in the second can felt like if it was pretty close to 4 oz, but I can\'t say for certain. At this point it was cooling well, and the compressor was acting like it was supposed to but again I was looking at 30 psi on the low side and around 225 on the high side. That\'s when I really started looking for the factory shop manual, which I managed to locate. Evidently the numbers I was seeing posted everywhere (product boxes, manuals, you name it) said 30 and somewhere under 200 on the high side. Evidently those readings are usual for an R12 system, and the R134a systems evidently have a higher high side pressure. The book says at 80 degrees I should have a low side pressure of 32-41 psi, and a high side pressure of 200-260 psi, so it\'s right about where it should be. It\'s certainly getting cold .

One thing that happened that really pi$$ed me off during this process was my gauge set. The darn lines say r134a all over them. Unfortunately the connectors are all r12! I wound up buying a new manifold gauge set at Autozone, and I have to say I really like them. The set cam with the good r134a quick connectors that allow you to connect the line before you open the valves on the system - no loss of freon or introduction of air at all. This set also has a much nicer sight glass, so you can actually see when freon is flowing and also has a valve above the yellow hose, so it\'s easier to purge the line. Even came with a nice carrying/storage case.

Sorry for the \"\\s\" in the above. The only way I can get at this site right now is through a proxy server, and it does some weird stuff. Hopefully my isp will get this sorted out soon.

[dbeardslee]

In my travels...

...I found this video on how to make a homemade Redneck freon reclaimer. Unfortunately going through this proxy server I can\'t access all the messaging tools, so this is going to have to be a cut and paste operation. Here\'s the url for the video (hopefully the proxy server won\'t put a bunch of extra punctuation in it) - http://www.wonderhowto.com/how-to-ho...laimer-218325/

[motoman]

Glad To hear we all could be of XSessive help! Also, your respones ended up being very imformative....,least for me, thanks.

[dbeardslee]

The plot thickens

So I went out to check my ac today, and the pumps cycling on and off again when throttle is applied. I wanted to check the pressures again, but I did not want to take any chances of introducing air to the system, so the first thing I did was attach the gauges by themselves to my vacuum pump, vacuumed down the lines and closed the valves to the red and blue. I then removed the pump, put the freon back on it and purged the yellow line. Then I opened the blue and red valves and allowed the vacuum to suck freon into the lines, and closed the valves. That gave me gauge lines that were air free and charged with freon. I then connected the quick connects, and turned the valves on (man I\'m lovin\' this gauge set). Static charge looked maybe a tad low. I turned the ac on full, and both the low pressure side and high pressure side were a bit low. I allowed a little more freon into the system using my previous rpms-at-1.5-2k-keep-the low-side-above-20-psi method, and the compressor started behaving again. Gauges are all showing normal ranges on high and low sides based on the jeep factory service manual for the current ambient temperature.

Here\'s what I think happened. I think I put just enough freon in it yesterday for it to function properly - at 82 degrees ambient temp. Today it\'s about 12-15 degrees cooler, allowing the low side pressure to get below the magic 20 psi point where the low pressure switch kicks in.

I wanted to post a pic of the gauge set, but alas, this darn proxy server won\'t let me do it. If you are interested you will have to settle for this caveman style link - http://www.autozone.com/autozone/cat...and+Components

[DGXSER]

I'm interested in seeing how the system performs for you in the next day or two. My guess is you have a leak in the system and it will continue to lose Freon.

BTW, for those unfamiliar with freon systems, there are several types of freons on the typical systems home owners deal with. R-12 in older cars (like 1980s or so) R-134a in more recent cars, and R-22 in most home AC systems. So if you build one of those revoery systems in that video, you do not want to mix the freons together.

[dbeardslee]

I had the same thought, but the system held 29 inches of vacuum for 5 minutes without loosing anything when I evacuated it. I really think it was just slightly undercharged, but I will keep an eye on it.

I liked the guys redneck recovery system. Looked like an excellent way to be kind to the environment on the cheap, but you made a good point about the types of freon. I had an old window unit that I threw out last year. Now I am wishing I had kept it .

[dbeardslee]

Well, looks like you were right Don. I went out to check it again, and it is acting up again. I think I found the problem, though. When I shut it off I heard freon escaping for a couple seconds, then it stopped. I could tell where it was coming from, and the high side quick connect had some freon or oil around it. That would explain how it could leak out, and still pass the vacuum test - the valves are open when it is being vacuumed, so they are not being tested. I hope that is the only problem. Looks like I\'ll get to evacuate and charge it again. Anyway, good call, Don.

[XSokieSPECIAL]

Hey Doug...

Glad I could be of some help. Hope you've got it all sorted out now.

Sorry, I should have said something about checking the service ports for leaks. I just do it habitually and didn't think of it.

One thing, when you recharge put in about an oz. of pag oil with dye in it. If the freon leaks out again it will give you a good way to look for leaks. It shows up under a UV light but most of the time you can see it without.

Good Luck!