whos a ac tech
06-16-2011, 04:23 PM
#2
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Year: 1996
Model: Cherokee
Engine: 4.0
Until someone useful shows up, I am glad to help. Roll windows down, stick head out. Not cool enough? Go faster. To cool? Slow down. Avoid sign posts.
A noob always willing to help
Fsher21
A noob always willing to help
Fsher21
06-16-2011, 05:00 PM
#6
Yes they do have a perssure switch,.. my 97 has one, and my ZJ had one. The ZJ's a/c leaked out, so the a/c clutch would engages for a few seconds, it would moniter the pressure switch to see if there is a raise in pressure(which there wasnt) and it would turn off. It would go through this cycle every 10 secs if i had the defrost on.
From my 99 FSM,.. there is a High pressure Cut off switch(located on the discharge line between the compressor and condensor inlet), a High pressure relief valve(located on top of the compressor head), and a lower pressure cycling clutch switch(located on the top of the accumulator.)
From my 99 FSM,.. there is a High pressure Cut off switch(located on the discharge line between the compressor and condensor inlet), a High pressure relief valve(located on top of the compressor head), and a lower pressure cycling clutch switch(located on the top of the accumulator.)
Last edited by Mattpar; 06-16-2011 at 05:16 PM.
06-16-2011, 05:03 PM
#7
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
On a '98, the hi-pressure switch is in the discharge line at the compressor. the low pressure switch is at the accumulator/dryer. Not sure about a thermostatic switch.
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06-16-2011, 05:18 PM
#9
Per my 99 FSM,.. there is no thermatic switch,...
"The lower pressure cycling clutch switch is connected in series electronically with the high pressure cutoff switch, between ground and the PCM. The Switch contacts open and close causing the PCM to turn the compressor clutch on and off. This regulates the refrigerant system pressure and controls evaporator temperatures. Controlling the evaporator tempature prevents condensate water on the evaporator fins from freezing and obstructing air conditioning system air flow"
"The lower pressure cycling clutch switch is connected in series electronically with the high pressure cutoff switch, between ground and the PCM. The Switch contacts open and close causing the PCM to turn the compressor clutch on and off. This regulates the refrigerant system pressure and controls evaporator temperatures. Controlling the evaporator tempature prevents condensate water on the evaporator fins from freezing and obstructing air conditioning system air flow"
Last edited by Mattpar; 06-16-2011 at 05:22 PM.
06-16-2011, 05:36 PM
#10
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Per my 99 FSM,.. there is no thermatic switch,...
"The lower pressure cycling clutch switch is connected in series electronically with the high pressure cutoff switch, between ground and the PCM. The Switch contacts open and close causing the PCM to turn the compressor clutch on and off. This regulates the refrigerant system pressure and controls evaporator temperatures. Controlling the evaporator tempature prevents condensate water on the evaporator fins from freezing and obstructing air conditioning system air flow"
"The lower pressure cycling clutch switch is connected in series electronically with the high pressure cutoff switch, between ground and the PCM. The Switch contacts open and close causing the PCM to turn the compressor clutch on and off. This regulates the refrigerant system pressure and controls evaporator temperatures. Controlling the evaporator tempature prevents condensate water on the evaporator fins from freezing and obstructing air conditioning system air flow"
06-16-2011, 05:44 PM
#11
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Year: 2002
Model: Grand Cherokee
Engine: 4.0 I6
I'm barely getting into HVAC but from what I've studied.... A typical TXV has a temperature sensing bulb filled with fluid, and is on the suction line at the end of the evaporator. When the heat load increases the pressure in the bulb increases, it is connected to a diaphragm which expands and pushes open a valve seat allowing more refrigerant into the evaporator. And I know there are other types of TXV's that use a thermistor (also at the end of the evaporator in the vapor stream). Don't know if this applies to automotive, I haven't got to that section yet!!! Or maybe a thermostatic switch is something completely different, what ever it is, it would some how be connected to the expansion valve.
06-16-2011, 05:48 PM
#13
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
I'm barely getting into HVAC but from what I've studied.... A typical TXV has a temperature sensing bulb filled with fluid, and is on the suction line at the end of the evaporator. When the heat load increases the pressure in the bulb increases, it is connected to a diaphragm which expands and pushes open a valve seat allowing more refrigerant into the evaporator. And I know there are other types of TXV's that use a thermistor (also at the end of the evaporator in the vapor stream). Don't know if this applies to automotive, I haven't got to that section yet!!! Or maybe a thermostatic switch is something completely different, what ever it is, it would some how be connected to the expansion valve.
06-16-2011, 06:05 PM
#15
I cant seem to find any info on it. Rockauto/autozone dont list a part for it, nor does my manual mention anything about a thermostatic switch. Google just got me thermostatic switches for the coolant system that operate the radiator fan,... Either I am missing it, cant find it, or you are calling it something else,...