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  #1  
Old 05-03-2006, 01:47 AM
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Location: joshua tree
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a/c cycling switch

could the low pressure switch also called a cycling switch...

i just lost my shift key and gained 2 pounds of r-12 and a working a/c system, except for a cycling switch...question..

the shop were i had the system charged at suggested that i install a new cycling swith, they wanted one hundred dollars for it ... is it a low pressure sitch..

i've got to get that shift key working, it's hard to ask questions without that mark.

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  #2  
Old 05-03-2006, 09:03 AM
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Location: Wesley Chapel, Florida
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Yes, I believe so. There's two switches on the accumulator or dryer. One is a pressure switch & the other a temp. switch. The cycling or pressure switch will require the charge to be lost though (Don't believe there's a schrader valve below it) It does not cost that much to buy. This is on a W123? or 126?
By the way, your location, by Joshua Tree National Park in Calif? Paul.
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  #3  
Old 05-03-2006, 09:42 AM
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Quote:
Originally Posted by buck moberly
could the low pressure switch also called a cycling switch...
No. It is common to replace the low pressure cut-out switch with a dual action low-high pressure switch when converting to R-134A. Since you stayed with R-12, save your money. How many years has the a/c been working with just a low pressure switch?

Last edited by tangofox007; 05-03-2006 at 12:37 PM.
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  #4  
Old 05-03-2006, 12:18 PM
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Join Date: Feb 2006
Location: joshua tree
Posts: 12
so... does the low pressure switch have anything to do with cycling the compressor... question.
i don't want to replace the r12 again, it cost me 20 percent of what i have into the car.

the a/c temp switch.. could that be the switch the shop was talking about when the said the system gets too cold, does not cycle... question.

i've never worked on a a/c system before, i should learn more, i'm in the middle of building myself a house, a full mind.

yes, i do live by the park, it borders the land i have, i'll have protected views, well unless they find oil there.
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1993 w250 Dodge cummins,wvo,tweaked pump,etc
1969 Baja bug, vert, 3x3, mid travel, 1914, fun
1979 300sd not so bad
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  #5  
Old 05-03-2006, 12:19 PM
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Join Date: Oct 2005
Posts: 4,263
Quote:
Originally Posted by buck moberly
could the low pressure switch also called a cycling switch...

i just lost my shift key and gained 2 pounds of r-12 and a working a/c system, except for a cycling switch...question..

the shop were i had the system charged at suggested that i install a new cycling swith, they wanted one hundred dollars for it ... is it a low pressure sitch..

i've got to get that shift key working, it's hard to ask questions without that mark.
Some cars have a pressure switch in the low side, which is a cycling switch. Its job is to turn the compressor off when the low side has sufficiently low pressure.

Your car is not among them. There is no cycling switch in your system. The low-pressure switch is on the high side, and prevents the compressor from starting in the first place if you're low on refridgerant, but it won't cut it off once it starts.

The switch that they want to install is a high side cutout switch which turns off the compressor if the high side gets too high, and is required for HFC134a conversions, but not required for R12, and shouldn't be needed.
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  #6  
Old 05-03-2006, 12:42 PM
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Quote:
Originally Posted by buck moberly

the a/c temp switch.. could that be the switch the shop was talking about when the said the system gets too cold, does not cycle... question.

The temp switch on the receiver/drier has nothing to do with the compressor. Its purpose is to turn the aux cooling fan on when (and if) the a/c refrigerant temp rises to a specified level.
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  #7  
Old 05-03-2006, 07:21 PM
LarryBible
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There are two switches, one for control of the aux fan and the other for low pressure protection to prevent compressor destruction in the event of an empty system. This is not a cycling compressor system.

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