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AC Clutch Cycles


damone

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Previous owner told me clutch was bad. replaced with junkyard clutch and still cycles. Is this a sign or bad clutch?

Is there a way to check to see if the clutch is good/bad?

Can you add 134 to R12?

How can you tell if you have R12 bs 134?

Clutch cycles and when trying to add fluid the pressure raises until the clutch cycles and it falls to correct reading in gauge right when clutch cycles off (1 sec.). Do you think some fluid is getting in when the clutch cycles. Maybe eventually enough will get in keep cluctch engaged?

Will the system take fluid w/o the clutch engaged?
 
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XTC90BII

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You need to change the dryer and then draw down the system before installing the R134a. The clutch will engage when enough R134a is added to the system and will stay engaged. Set the gauge by the ambient temp. Keep the can upright and rock side to side
Post a picture of your shredder (sp) valve if you can (that is the valve you use to fill the system)

Dennis
 

damone

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The can snaps right on.

Do I need to change the dryer if there is already 134a and I am just adding?
 

XTC90BII

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No not if it has already been converted to R134a. Look for some type of sticker in the engine bay area or on under hood that might say when/if it was converted to 134a. If the system has not worked for awhile because of a leak there is a good chance that there is moisture in the system. You should put the system under vacuum and see if it holds. That way you will know if there is a leak and it will pull the moisture out of the system. If you are not going to check for a leak then put a can of 134a with leak stop/dye in and then you might be able to see where the leak is if the stop leak does not close it up.

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damone

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Previous owner told me the clutch was bad. When I first engaged the AC the clutch would cycle on and off continually. I replaced the clutch with one from the junkyard. Still cycles on and off. Is this a sign of bad clutch or low 134a or ?????
 

XTC90BII

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Hard to say? Put a can of 134a with stop leak in and see if it stays engaged. Your out $8-10 bucks depending on the cost of the 134a.

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JerryC

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The clutch should cycle by refrigerant pressure.
Goes too low it turns off. I don't know if BII's have a high pressure cut off from the factory.

In the summer cycling would typically indicate low refrigerant level. "I think" in the winter the cold air causes the pressure to drop and the clutch turns off, as the refrigerant warms up the pressure raises and the clutch engages.
 

damone

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Thanks for the replies.

I have a can. I will sit and let it cycle for awhile while I fill it. See if it stays engaged. I imagine just a little bit of refrigerant is getting in only when the clutch cycles on (indicated by pressure dropping to between the guage indicator then it spikes again until clutch engages. I will sit through this for a consideable amount of time and report back.

Thank Again,
D
 

wildbill23c

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The clutch will cycle on and off as part of how the AC system works. However, frequent fast on/off cycles means the system is not properly charged. The proper way to do this is to use a set of AC gauges, those gauges on the refrigerant cans are useless for properly checking and charging an AC system. Pressures will vary depending on the outside temperature.

The best thing to do is vacuum down the system, leave a vacuum on it for about 1/2 hour to insure the system is properly evacuated, then shut the vacuum off and keep an eye on the gauge set, if the pressure starts coming up in the system it means there's a leak somewhere and that will need to be fixed before trying to charge the system. The leak could be anywhere so use an AC refrigerant dye, and add enough refrigerant to the system to be able to look around with a UV light to find leaks, many leaks are found in the O-rings where lines connect to different areas of the system.

My 88 Bronco 2's AC didn't work when I got it, I spent the money and got the tools and parts to fix it myself...I think it was like $500 between parts, refrigerant, compressor, accumulator, orifice tube, ac manifold gauge set, vacuum pump, etc. Took a few days to get it done waiting on parts to arrive that I ordered, but I was relaxing in a 30 year old truck all summer long with nice ice cold AC. I checked with a couple local shops and was quoted $1800-2200 to "convert" and repair the AC system.
 

damone

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After putting 2 less than 1/2 full bottles of 134 in, the clutch stays on much longer and blows somewhat cold. It’s hard to tell cuz it’s cold out but it definitely is working.

$12 clutch from salvage 1/2 a can of 134 from neighbor who wanted his deposit back , my half can from 1.5yrs a go and the 33 yo system is working.

Thanks for the help.
 

wildbill23c

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Awesome. I'd vacuum down the system and check to make sure there aren't any leaks, rather you may want to take the ac lines apart and replace the o-rings at all the connections, replace the orifice tube and the accumulator then recharge the system properly. Now that you know it works, I'd get it serviced and ready to go for the summer...unless you have the equipment or want to get the equipment to do the work yourself. I found it to be a great learning experience, first time I'd ever worked on an AC system, well other than adding refrigerant to an already working system that was just low.

People thought I was crazy when I told them last summer that the AC in my 88 Bronco 2 worked LOL. I couldn't imagine driving that thing around in 100+ degree temps without AC, that thing is an oven. Can't tell you how hot it got but had to be 140+ degrees as the inside thermometer I had just said HH, meaning it was way above its ability to read the temp.
 

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