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#2263050 - 03/21/11 08:33 AM To Charge or not to Charge the A/C
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
Hi,

I'm trying to decide if it worth it or a waste of time and money to try a can of R134a to improve the performance of my A/C. Since last fall, it hasn't been doing much cooling. It did work fine all winter as a defroster, except for one night, it fogged up all the windows instead. Since it was so late in the year, I put it off until now, when we are starting to get some 80 degree days.

I'm getting only down to ambient temperature when I run the A/C and the clutch has a 5 second cycle, 2 engaged and 3 disengaged. I first noticed this last fall when I had to use the car one day and what was normally in the low to high 40 degree range was suddenly 60 degrees coming out of the dash. I tried to put a can of refrigerant in then but it didn't seem to take it. The can didn't get cold and the cycle times were still the same. I didn't know the trick about jumpering the low pressure cycling switch then, don't know if that will make any difference.

Nothing's been done to the system for at least the 6 years I've had it, although 5 years ago, I took it to the dealer when it seemed to be a little bit down in cooling. They did a performance and leak test and couldn't find any reason to take more than the $96 that the test cost. I've kept a thermometer in the dash since then, to keep an eye on it. Since I drive mostly at night, the 40ish coming out was good. Last year it was a little warmer, sometimes only down to about 50. I chalked it up to all the 90+ days we had.

Last week, the weather got up to about the low 80's; inside car temp was about 110 degrees. The A/C only got down to about 80 after about 10 minutes of driving around town. Still have the rapid cycling and nothing is sweating under the hood. I did the jumper thing and I did get it to engage continuously but I didn't like the way the compressor sounded so I only left it on for about 10 seconds.

I got one of the Harbor Freight manifold gauge sets, seems to work OK. When I first measured the static pressure, I got 50 psi. The book calls for 60-80 psi at 75 degrees ambient. I couldn't make much sense out of the high and low readings, but since it was only about 65 degrees outside, I waited for a few days for the temp to come back up to at least 75 to try again. I did go for a drive and the A/C only got downn to about 65 degrees. Last weekend, back up into the 80's ambient, I got a static pressure of 60. I got about 22 to 40 psi on the low side in time with the cycling switch. The high side was about 150 psi, +/- 10 psi also in time with the cycling. The register temp only went down to about 80 degrees after about 10-15 minutes on max.

I want to do as much as possible myself, but don't want to screw it up. I don't want to pay somebody else to r&r parts, but this is more technical than I want to spend on tools and other specialized equipment to do it all myself. I'm figuring a can of refrigerant in the system should make some difference at least in the rapid cycling and dash temps to let me know if I'm heading in the right direction.

Would the jumper on the switch keep it on long enough to take the R134a this time, or would I be better off taking it to the pros rather than breaking something that isn't broke now? I'll probably end up doing that anyway, but I just hate to take it anywhere without knowing exactly what needs to be done. I'd appreciate any input.

Jim
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2263083 - 03/21/11 09:45 AM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
98P73_IRAQ Offline
Over the Hill

Registered: 04/26/08
Posts: 2945
Loc: iraq-baghdad-hell's street
the A/C ompressor could be weak and not givving the desired compression ratio. the high side pressur is supposed to be 150+ psi in the 20-25C ambient temprature. to get more accurate values visit BOK and www.p71interceptor.com .
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#2263267 - 03/21/11 03:11 PM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
Frankie4speed Offline
Frankie the Fighter
Climber

Registered: 09/21/06
Posts: 554
Loc: AZ
It sounds like you are a little low on 134a.If the comp runs even for a couple of seconds it should be enough to start sucking in the gas.If you are not sure how to use the manifold set, don't.I think suction press should be about 35 lbs. With comp running.Try it again with another can. Like i said if you are unsure of the manifold set use the little hose and a 1 lb can.
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#2263277 - 03/21/11 03:24 PM Re: To Charge or not to Charge the A/C [Re: 98P73_IRAQ]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
I have the shop manual for my car. It has all of the graphs and charts in the Climate Control System chapter. The one I'm keying in on is the Clutch Cycle Timing Evaluation chart. The only thing I can see that matches the symptoms is high pressure-normal to low; low pressure-normal; cycle rate-fast; both on and off times-short to very short gives a cause of Low refrigerant charge.

I believe I'm reading this right according to my manifold gauge. But I could be all wrong. I don't have any real hands on experience servicing hvac, just what I have been able to research here and a few other places. All the pressure numbers meant nothing to me even a week ago.

I have a feeling all that time with nothing done to the A/C has caught up with it, as I undertand there is some natural leakage in these systems.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2263295 - 03/21/11 03:58 PM Re: To Charge or not to Charge the A/C [Re: Frankie4speed]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
I think I understand how to fill with the manifold set but it didn't come with connections to attach to the little cans. When the compressor came on, it would go down to about 22 psi, cut off and then back up to 40 psi, which is pretty much the range for the cycling switch. I would use the little hose to try again and switch over to the manifold set to see if it did any good.

Maybe I didn't give it enough time before. How long does it take to empty those little cans? Seems like when I tried before, nothing happened after 5 minutes. Could have been more, I don't remember exactly how long before I stopped trying.

Do you think it is necessary to jumper the cycling switch to get the compressor to stay on longer? Is that what it needs, to be on longer than 2 seconds? How low will that make the pressure go and what is acceptable without doing some sort of damage to the system. Seems that the lower it would go the harder it would suck the refrigerant in.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2263429 - 03/21/11 07:45 PM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
Frankie4speed Offline
Frankie the Fighter
Climber

Registered: 09/21/06
Posts: 554
Loc: AZ
22 psi is to low on the suction side with comp running.Get another can of 134a.Buy the kit with the hose.Follow the instructions.Put the A.C.on max ,fan on hi speed.As soon as the comp kicks on the can of 134a should get cold .Bring the R.P.Ms up a little.Shouldn't take more than 5-10 mins.Try holding a warm towl around the can.(Speeds up the process a little) What is the outside air temp?
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#2266054 - 03/25/11 07:57 PM Re: To Charge or not to Charge the A/C [Re: Frankie4speed]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
Well, I got it to take this time. I had to jumper the cycling switch, left it on for about 10 seconds at a time. The can started cooling down and I let it go until frost wouldn't form on it any more. It did take about 10 minutes til it was all gone. With the low side gauge hooked back up, I was getting 25-45 psig on the low side cycling with 5 to 6 seconds engaged, then followed by 3 seconds disengaged. That's heading in the right direction. That is with around 60 degrees coming out of the dash and about 97 degrees right in front of the condensor. High side would go up to about 180 psig.

Rather than continue, I found someone who will recover what R134a in there now for $30. I plan to get the kit to replace all the o-rings, the orifice tube and probably the accumulator. I'm sure the o-rings are in the same shape as the ones I replaced to fix my leaking oil cooler connections. The only rust I can see anywhere is some surface rust on the condensor end of the discharge line. I know where I can borrow a vacuum pump to check for leaks. Those o-ring kits look like they have more parts then are need. Besides the lines and the manifold on the compressor, where else do they need to be replaced?

The place that is recovering the refrigerant said they will recharge for $50, not much more than I could do buying cans from the parts place. I plan to drain the oil from the accumulator and compressor and add new oil while I have things apart.

I'm seeing these automatic adjusting orifice tubes, supposed to make the system work better when you have a lot of low speed city type driving and idling. Is that something worth looking into or just adding something else that could go wrong? They are a lot more expensive than the stocker.

Well, am I missing something? Unless I find something drastically wrong when I open up the system, there doesn't seem much more that I should do. But this is my first time working with the climate control system.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2266082 - 03/25/11 08:51 PM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
TechnoWeenie Offline
Banned
Posting Addict

Registered: 10/02/04
Posts: 22857
Loc: The perimeter
Be careful.

Ferd uses a different lubricant in its refrigant.

Most OTC refill kits don't use that lubricant, and can damage the system.
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#2266296 - 03/26/11 07:30 AM Re: To Charge or not to Charge the A/C [Re: TechnoWeenie]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
Thanks for the heads up. I saw the spec in the shop manual, wasn't even thinking about anything but pag 46. I'll make sure what I get meets the spec. It calls for Motorcraft YN-12b or spec WSH-M1C231-B, part number F2AZ-19577-AB. Probably a dealer only item.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2266456 - 03/26/11 03:02 PM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
fatflat Offline
Member

Registered: 05/09/10
Posts: 333
Loc: South FL
You have to evacuate the system to -30psi prior to recharging an opened/drained system. The "automatic adjusting orifice tubes" can give you a problem, so try to stay with the original design. Keep it simple. Way back when, we changed out the accumulator due to the dryer being in it. The dryer becomes contaminated when exposed to air/moisture from an opened system. Don't over oil the system. It's for the compressor. When the evaporators vacuum line starts to sweat the system is charged, or during high idle the sight glass has no bubbles passing through it the system is charged. The compressor will cycle on off if under or over charged. I assume today's systems haven't changed much, but you should save yourself time and frustration by paying a shop that gives warranty to repair the AC. The tools to get the job done right the first time aren't cheap and your in for a long process. Preferable to charge the system with the can upright (gas charge) vs upside down (liquid charge). Shaking the can while charging helps for quicker charge. Holding the can upside down (liquid) is for a faster charge. But do this intermittently for few seconds at a time. The compressor pounding on a prolonged steady liquid intake is not good. However maybe you know more than I think you do. Good Luck!

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#2266780 - 03/27/11 07:40 AM Re: To Charge or not to Charge the A/C [Re: TechnoWeenie]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
Damn, $25.90 for a 7 oz. can. I thought $9 for a 8 oz. bottle of "PAG 46" was high. I couldn't find any other that said it meets that spec. and the parts guy at Napa couldn't cross it in his books. I wonder how many indy shops would put that in? Well, it better last for at least another 6 years.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2266789 - 03/27/11 08:38 AM Re: To Charge or not to Charge the A/C [Re: fatflat]
Rootintootin Offline
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
That was my plan, to change the seals and o-rings myself, a new accumulator and FOT since I knew it would be open too long to reuse, new oil in the accumulator and compressor, and evacuate just well enough to check for leaks. Then take it to the shop for charging. That's supposing there are no more leaks after this work. I'll have to come up with plan B as the vac pump I was going to use is inop. I guess I could always buy a pump and resell it to recover that expense.

There is no sight glass in these systems. The compressor will cycle even with the proper charge too. And if the ambient temp is high, it might not cut off at all. My understanding is only liquid charge on the high side as liquid doesn't compress. The high pressure vapor coming out of the compressor is going to turn to liquid in the condensor anyway. I don't have enough experience to try playing with a few seconds of liquid on the low side, especially since it only takes time for it to be sucked in as a gas. Spending a couple hundred on a compressor because I screwed it up isn't the kind of OJT I want right now.

I'm trying to keep a running total on what I've spent so it doesn't get out of hand. But when I asked at the dealer about checking the system, they said up to $126 for the performance and leak test, just to start. That's up $30 from when I had it done 5 years ago. I didn't even ask about charging, and I can't see any reason to pay their rates just to change out some parts. The radiator shop recovering the refrigerant in there now gave me a price of $50 to charge it when I'm done changing parts, sounds like a good deal to me. And I might decide when the time comes to DIY charge. I'll cross that bridge when I come to it.

The WX just turned back to cool, so I can put the project on the back burner while I look for another vacuum pump. I appreciate any input, as I'm steadily learning as I go along.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#2266969 - 03/27/11 04:05 PM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
fatflat Offline
Member

Registered: 05/09/10
Posts: 333
Loc: South FL
Can't do much about your OJT time, but the positive is that it sure will help you understand whats going on after all is done! You have good ambition to do something that's going to be a real pain in your keister due to no experience! Oh well, at the moment a cheap way to find a leak is to put dye in the system. If you don't see anything then it is more than likely your evaporator coil. If this is the case, before removing anything related to the evap coil, I would check it with an electronic leak detector. Leave the evap coil alone if it does not leak. So, if everything checks OK after your leak test and when you have a vacuum pump, pull a vacuum to -30psi, turn the pump off, and leave the gauges or pump connected to the system for appx 30min. Of course, if vacuum is lost you didn't find the leak, or you fixed it but created another one. Btw, if you can't find dye use a thick soapy solution on all the fittings to find a (normally large)leak. But this method is no good with finding leaks in the condenser, evap coil or other parts. Overall, an electronic leak detector is the best option for finding leaks due to its quickness and reliability. You can use an old refrigerator compressor for a vacuum pump. Just braze a fitting on the low side tube for your connection to the gauges. Again, good luck.

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#2267951 - 03/29/11 11:28 AM Re: To Charge or not to Charge the A/C [Re: Rootintootin]
Kshaw Offline
Banned
Rookie

Registered: 08/28/10
Posts: 60
Loc: America
Make sure your evaporator and condenser coils are clean. Also you might wanna learn about how to take your super heat and sub cooling temperatures and learn what those pressures on the manifold mean. Technically this is illegal to do without a license and this topic should probably be filed under things against the law we can't talk about. The only way anyone without a license is supposed to be in possession of refrigerant like R134a is for resale. You are technically not supposed to have a manifold set in your possession without a license. And further more you need an automotive license to handle containers smaller than 50lbs I believe. Wal Mart and Autozone got in trouble a little while bag for selling refrigerant and retrofit kits. I have a ton of knowledge on this but it being illegal for those unlicensed to handle refrigerant I don't want to get things locked.


PS BTW there is a lot of wrong information from above posts so be advised if you don't know what you are doing.


Edited by Kshaw (03/29/11 11:54 AM)

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#2268687 - 03/30/11 09:30 AM Re: To Charge or not to Charge the A/C [Re: Kshaw]
fatflat Offline
Member

Registered: 05/09/10
Posts: 333
Loc: South FL
There is a lot of well meaning misinformation from any forum site you visit. That should be common knowledge in addition to one's awareness of having to validate what is stated in any forum prior to applying given information. I myself can't remember everything I learned in high school 40 years back concerning auto air conditioning, as I primarily applied the A/C knowledge to residential/commercial applications before the Marine gig. Now that trade info is vague. Yet the accumulated information posted here is to open ones eyes with knowledge of their interest. Providing air conditioning and refrigeration how-to information via any media is not illegal. Public sale of the refrigerant that cars currently use is wide open in South Florida as are the gauges. Concerning this fellow, he's in for a real mess tearing into the system if a simple charge doesn't do the trick. More power to him for trying. If I can remember correctly "The Poor Man's Cook Book" ,or something like that, is illegal information, but worthwhile/amusing reading.

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