A/C compressor runs..refrigerant .pressures are perfect, charge is correct, system runs for 5-8 minutes and shuts off. the only way to to restart the compressor is to pull the fuse and reinsert it. This to me indicates a control problem. The manual shows a thermister off of the ECM. Where is this thermister. Could thos be the problem? Thanks for any help....

The only way to know if a vehicle's air condition is properly charged is to use refrigerant gauges to determine the high side and low side pressure while the system is running. Without gauges, there are a few things you can check:

1. With ambient temperature over 85 degrees Fahrenheit, when you first start the engine for the day, the compressor should engage and stay engaged. If it cycles off and on for more than one minute, or if the compressor fails to engage at all, there is a likelihood that the refrigerant charge is low. (If ambient temperature is under 85 degrees Fahrenheit, a small amount of cycling is normal, but the compressor should remain engaged for a longer time than it is disengaged);
2. If the compressor is not engaging at all, momentarily place a wire jumper across the two pins of the refrigerant pressure switch connector with the engine running and the system on. The compressor should engage. If it does not, the system is not working properly. If it does, there is likely insufficient refrigerant in the system.

Correct charge procedure is: evacuate refrigerant from system. Vacuum system down. Wait and monitor vacuum to ensure no rise in pressure, if there is a significant rise than you have a leak. No leak? Recharge system with specified quantity of refrigerant, normally to the high side of the system. If you have been following this and are having problems then try charging to the low side, but feather the refrigerant in to the system as you DO NOT want liquid refrigerant to get to the compressor. Once the system has started to charge, start the engine and turn the system on. The suction of the compressor should now draw in the remaining refrigerant. Be sure to feather the refrigerant in until the correct weight has been charged in to the system.

it's either low (in spite of your readings) or your a/c clutch is not working correctly or you have too big an air gap in the clutch.
First, just disconnect the 2 pin connector from the a/c pressure cycling swithc and jumper the 2 pins with a wire to force the clutch to stay engaged. See if it blows cold then, and stays engaged. You can run this way for about 15 minutes before you have to pull the plug.
report reulsts.

please don't forget to rate.

check the refrigerant level. The compressor is running until the low pressure or high pressure switch switch cuts it off.

Running the unit without enough refrigerant will damage the compressor because the lubricating oil is dissolved in the refrigerant. This is the reason for the low pressure switch cut off--to protect the compressor from damage.

If pressure gets too high, the compressor seals will blow. Thus the reason for the high pressure switch. Too much refrigerant or too much air in the system (due to a leak) will cause high pressures.

If refrigerant level appears to be correct, then suspect trapped air from a leak causing a high pressure cut-off. If refrigerant is low, suspect a leak causing a low pressure cut-off.

Sounds like a low pressure shutoff switch is working and there is not enough charge of freon, r134a, in the system.

suspect you have a low charge, the question is why ..possible leakage, if the condensor looks good (obvious damage from rocks or collision durring winter-pending on regions)complete a soapy water test on both high side and low side shradder valves.
this is not a problem for the at home do it your selfer
there are federal laws and regulations that must be
obided by with the usage and disposal of refrigerant
so if you are not a certified mechanic or refrigerant mechanic it is advised that this repair be completed
by a train professional with the facilty to handle this
enviromentally toxic and hamfull substance. what
type of refrigerant is being used on this vehicle-you should use an identifier (should be r134a) then either hook up gauges and read temp on condensor and evaporator (old school method, pressure temperature co-relations) or use a/c machine and evacuate the system place into a deep vaccum and monitor -either is passes or fails this just tests the systems interigty to hold a charge. peg oil and uv dye in recharge and run system looking for leaks (most shops use this method) at every connection-o-rings, and compresion fittings most common places for wear and tear.
now if the pressure is adequate-indicating the correct charge is applied-then you will have to figure out the saturation poin and the condensation points of the refrigeration, determine the style of compressor-variable displacment of cycling clutch, then determine if it is txv-or orfice tube a/c system and compare to manufacturer specs.

that is a low refrigerant sign you need to charge the system.. the compressor shuts off because the low preasure shutdown switch is triggerd when the compressor starts to move the refrigerant to the high side and shuts off thats why the preasure drops when the compressor clutch engages...

hope this helps.
Ron

You may be low on R134a and need a simple charge. As the Compressor cycles, the low side pressure drops and if it drops to far it will cut the compressor off till the pressure rises again. The high pressure side rises and the low side drops, but when it drops to far since there is not enough R134a in the system you get the on off cycle. The other cause to this is a bad pressure switch, or bad expansion valve, and moisture in the system as it ices up in the lines and pressure builds causing the pressure switch to cut the compressor off too. Re-cap, try recharging the a/c system for now since it's still working. Good luck and keep me posted. Be glad to help.

The system could be low on oil. The compressor will shut itself down if it detects a lack of oil or refrigerant. Try adding compressor oil (comes in a can similar to the R-134A) to see if the compressor will stay engaged long enough to accept a charge. It's also possible that the system has so much air in it that it needs to be evacuated before refrigerant can be added. I'd try to add the oil and see if you have better sucess adding refrigerant REMINDER: Have AC on HIGH when adding refrigerant with car running

Hope this helps with your AC problem. Please post back with any other questions. Best of luck.
Greg

You need to replace the condensor, then take it to a shop to have the a/c system evacuated and recharged to purge moisture because the system was opened. That will cost around $150. You do not need to replace the receiver/dryer/suction accumulator even though they will tell you that you do.
go to car-part.com to find prices of condensor from salvage yards. Page with asterisk on it is the lowest priced part.

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The Refrigerant Cycle
During stabilized conditions (air conditioning system shutdown), the refrigerant is in a vaporized state and pressures are equal throughout the system. When the A/C compressor (19703) is in operation it increases pressure on the refrigerant vapor, raising its temperature. The high-pressure and high-temperature vapor is then released into the top of the A/C condenser core (19712).
The A/C condenser core, being close to ambient temperature, causes the refrigerant vapor to condense into a liquid when heat is removed from the refrigerant by ambient air passing over the fins and tubing. The now liquid refrigerant, still at high pressure, exits from the bottom of the A/C condenser core and enters the inlet side of the A/C evaporator core orifice (19D990).
The A/C evaporator core orifice is the restriction in the refrigerant system that creates the high pressure buildup in the A/C evaporator core (19860) and separates the high and low pressure sides of the A/C system. As the liquid refrigerant leaves this restriction, its pressure and boiling point are reduced.
The liquid refrigerant is now at its lowest pressure and temperature. As it passes through the A/C evaporator core, it absorbs heat from the passenger compartment airflow passing over the plate/fin sections of the A/C evaporator core. This addition of heat causes the refrigerant to boil (convert to gas). The now cooler passenger compartment air can no longer support the same humidity level of the warmer air and this excess moisture condenses on the exterior of the evaporator coils and fins and drains outside the vehicle.
The suction accumulator/drier (19C836) is designed to remove moisture from the refrigerant and to prevent any liquid refrigerant that may not have been vaporized in the A/C evaporator core from reaching the A/C compressor. The A/C compressor is designed to pump refrigerant vapor only, as liquid refrigerant will not compress and can damage the A/C compressor.
The refrigerant cycle is now repeated with the A/C compressor again increasing the pressure and temperature of the refrigerant.
The A/C cycling switch (19E561) interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. It does this by monitoring low side line pressure. It is known that a refrigerant pressure of approximately 210 kPa (30 psi) will yield an operating temperature of 0°C (32°F). The A/C cycling switch controls system operation in an effort to maintain this temperature.
The high side line pressure is also monitored so that A/C compressor operation can be interrupted if system pressure becomes too high.
The A/C compressor pressure relief valve (19D644) will open and vent refrigerant to relieve unusually high system pressure.
Clutch Cycling Orifice Tube Type Refrigerant System
Item Part Number Description 1 19E762 A/C charge valve port (low side) 2 19E561 A/C cycling switch 3 19C836 Suction accumulator/drier 4 19703 A/C compressor 5 19D644 A/C compressor pressure relief valve 6 19D594 A/C pressure cut-off switch 7 19E762 A/C charge valve port (high side) 8 19712 A/C condenser core 9 19D990 A/C evaporator core orifice 10 19860 A/C evaporator core 11 — Low pressure vapor 12 — High pressure vapor 13 — Low pressure liquid 14 — High pressure liquid

1. Connect the R-134a A/C Refrigerant Center to the low- and high-pressure service gauge port valves.
2. Evacuate the system until the low-pressure gauge reads at least 99.4 kPa (29.5 in-Hg) (vacuum) and as close as 101.1 kPa (30 in-Hg) as possible. Continue to operate the vacuum pump for a minimum of 45 minutes.
3. Turn off the evacuation pump. Observe the low-pressure gauge for five minutes to make sure that the system vacuum is held. If vacuum is not held for five minutes, leak-test the system, service the leaks, and evacuate the system again.
4. Correctly oil match the system to verify that the correct amount of refrigerant oil is present in the system. For additional information, refer to Refrigerant Oil Adding in this section.
5. Charge the system with the specified weight of refrigerant and refrigerant oil.
6. When no more refrigerant is being drawn into the system, start the engine and select MAX A/C operation. Set the blower motor speed to maximum and allow the remaining refrigerant to be drawn into the system. Continue to add refrigerant into the system until the specified weight of R-134a has been added. Close the charging cylinder valve and allow the system to pull any remaining refrigerant from the hose. When the suction pressure drops to approximately 207 kPa (30 psi), close the charging hose valve.