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  #1  
Old June 20th, 2009, 16:29
chpmnsws6 chpmnsws6 is offline
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High pressure cutout switch not working?

Tested the jeep today after getting tired of not having AC. The low side is fine but the high side is hitting over 300psi. What do the high pressure cutout switches stop them at? When you manually cycle the compressor it blows cold. Any insight? Overfilled? Low?
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  #2  
Old June 20th, 2009, 16:30
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

http://www.bestvalueautoparts.com/it...ON S&weight=1

If the high pressure switch is needed, is this it? How do you test the switches?
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  #3  
Old June 20th, 2009, 16:39
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Saudade Saudade is offline
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Re: High pressure cutout switch not working?

"The high pressure cut-off switch contacts are open when the discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The switch contacts will close when the discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi)"

per the FSM

What's the low side reading when the compressor runs? Does it run at first, then cut off?
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  #4  
Old June 20th, 2009, 21:28
lawsoncl lawsoncl is offline
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Re: High pressure cutout switch not working?

Hmm. My 97 FSM says 500-600 psi on the high pressure cutoff, returning to normal at 400 psi. High side pressure depends on the ambient temperature, 300 psi is normal if its 90-100*F out. If its not that hot out, the FSM says check the condenser for airflow blockage or the system is overfilled.
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  #5  
Old June 20th, 2009, 22:34
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Saudade Saudade is offline
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Re: High pressure cutout switch not working?

Quote:
Originally Posted by lawsoncl View Post
Hmm. My 97 FSM says 500-600 psi on the high pressure cutoff, returning to normal at 400 psi. High side pressure depends on the ambient temperature, 300 psi is normal if its 90-100*F out. If its not that hot out, the FSM says check the condenser for airflow blockage or the system is overfilled.
That would be the relief valve on the compressor. The cut-off is the section before it.
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Old June 20th, 2009, 23:02
lawsoncl lawsoncl is offline
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Re: High pressure cutout switch not working?

Whoops. You're right. I was thinking 450 was right, but wasn't paying enough attention when I looked.
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Old June 20th, 2009, 23:19
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Re: High pressure cutout switch not working?

Quote:
Originally Posted by lawsoncl View Post
Whoops. You're right. I was thinking 450 was right, but wasn't paying enough attention when I looked.
Point is the rest of your previous post was right on. 300 PSI is not excessive, at least not enough for the cut-off.
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Old June 20th, 2009, 23:46
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

25-30psi on the low side. It staggers at 300psi (like the pump cannot push anymore)
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Old June 20th, 2009, 23:48
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

Quote:
Originally Posted by Saudade View Post
"The high pressure cut-off switch contacts are open when the discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The switch contacts will close when the discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi)"

per the FSM

What's the low side reading when the compressor runs? Does it run at first, then cut off?

Sometimes it will blow cold for a half hour or so, then will die out.
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  #10  
Old June 21st, 2009, 05:42
lawsoncl lawsoncl is offline
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Re: High pressure cutout switch not working?

Quote:
Originally Posted by chpmnsws6 View Post
Sometimes it will blow cold for a half hour or so, then will die out.
Inside evaporator freezing up? I vaguely recall that being an issue on some years?
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Old June 21st, 2009, 06:48
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Re: High pressure cutout switch not working?

If your evap is freezing up, the airflow though the vents will be reduced. THe inlet line under the hood will still be frosty.
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Old June 21st, 2009, 23:11
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

How do you test it? Check duct temps and see how cold they are getting before it heats up?

How many ounces of R134 does the system take (2001)?
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  #13  
Old June 22nd, 2009, 13:40
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

Bypassed the low pressure switch. It idles up but the compressor does not kick on. Next step?
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  #14  
Old June 22nd, 2009, 13:42
chpmnsws6 chpmnsws6 is offline
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Re: High pressure cutout switch not working?

Also purged it some to see if 134 will come out. Its nothing but air coming out
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Old June 22nd, 2009, 17:39
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Re: High pressure cutout switch not working?

Evacuate and refill. Holds 1.25lbs (at least in a 2000).
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