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High pressure cutout switch not working?

chpmnsws6

NAXJA Forum User
Location
Springfield IL
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?
 
"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?
 
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.
 
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.
 
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.
 
"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.
 
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)?
 
I'll give it a shot

What else could keep the compressor from turning on? Does the 2001 have an Evaporator sensor?
 
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Checked pressures and they were good while the compressor ran (225-300 and around 15-35). duct temps are in the mid/low 40's so that was good. I turned the AC off and then back on..... nothing happened when I kicked it back on.

This thing has me stumped
 
Might have too much pressure buildup when you turn it off, making high pressure switch keep it off. After it sat a little while would it restart the compresor? I don't think we have evap sensors.
 
Gave up and am taking it into a shop. 106 degrees outside while working under the hood is NOT my idea of fun
 
Clutch was bad. It was just starting to go out so it'd work when cold but once it was hot, it would not grab. Compressor is changed and hopefully all is well now.
 
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