ok, I did not know if you had a leak or something. in any event the refrigerant flows from the orifice to the evaporator and without getting to techy the r134a gets cold after it is adjusted by the orifice.so if you get some frost on the line that is normal. there are times it would be an indication of something wrong but tipicaly you would not be getting any cold air inside. hope this helps.let me know if you want more info.

ok so you replaced the lines because you did not have cold air. when you removed the accum was it blown up? were there little white beads in it or visable in the line? does it cool ok at first then get warm? if the line in is frosted and the line out is hot and it is still blowing warm air there could be a problem with the blend door in the hvac housing but if the air is cold at first then gets warm you may have a low pressure cut out switch problem (mounts to the accum). let me know and we can go from there.

ok fast on off cycles would tipicaly indicate a low system charge, but since you just replaced parts and had it charged it could be high press. if that accum was blown, there could be desicant in the lines blocking refrigerant flow. could you answer the questions in the last post to give me more info please.

hmmm, yes the line will frost up if the switch is bypassed. you dont happen to have any high and low side pressure readings do you? idle and 2000?

those pressures sound ok. here are some tests to run. A/C PERFORMANCE

The air conditioning system is designed to provide the passenger compartment with low temperature and low humidity air. The evaporator, located in the heater-A/C housing on the dash panel below the instrument panel, is cooled to temperatures near the freezing point. As warm damp air passes through the cooled evaporator, the air transfers its heat to the refrigerant in the evaporator tubes and the moisture in the air condenses on the evaporator fins. During periods of high heat and humidity, an air conditioning system will be more effective in the recirculation mode (Max-A/C) With the system in the recirculation mode, only air from the passenger compartment passes through the evaporator. As the passenger compartment air dehumidifies, the air conditioning system performance levels improve.

Humidity has an important bearing on the temperature of the air delivered to the interior of the vehicle. It is important to understand the effect that humidity has on the performance of the air conditioning system. When humidity is high, the evaporator has to perform a double duty. It must lower the air temperature, and it must lower the temperature of the moisture in the air that condenses on the evaporator fins. Condensing the moisture in the air transfers heat energy into the evaporator fins and tubing. This reduces the amount of heat the evaporator can absorb from the air. High humidity greatly reduces the ability of the evaporator to lower the temperature of the air.

However, evaporator capacity used to reduce the amount of moisture in the air is not wasted. Wringing some of the moisture out of the air entering the vehicle adds to the comfort of the passengers. Although, an owner may expect too much from their air conditioning system on humid days. A performance test is the best way to determine whether the system is performing up to standard. This test also provides valuable clues as to the possible cause of trouble with the air conditioning system.

Review the Service Warnings and Precautions in the General Information section near the front of this group before performing this procedure. The air temperature in the test room and in the vehicle must be a minimum of 21° C (70° F) for this test.

1.Connect a tachometer and a manifold gauge set.
2.Set the heater-A/C mode control switch knob in the recirculation mode (Max-A/C) position, the temperature control knob in the full cool position, and the blower motor switch in the highest speed position.
3.Start the engine and hold the idle speed at 1,000 rpm with the compressor clutch engaged. If the compressor clutch does not engage, see the A/C Diagnosis chart in the Diagnosis and Testing section of this group.
4.The engine should be at operating temperature. The doors and windows must be open and the hood must be mostly closed.
5.Insert a thermometer in the driver side center A/C (panel) outlet. Operate the engine for five minutes.
6.The compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, unplug the low pressure cycling clutch switch wire harness connector from the switch located on the accumulator Low Pressure Cycling Clutch Switch - Typical Place a jumper wire between the two cavities of the low pressure cycling clutch switch wire harness connector..
7.With the compressor clutch engaged, record the panel outlet discharge air temperature, the discharge pressure (high side), and the suction pressure (low side)
8.Compare the panel outlet discharge air temperature reading to the Performance Temperature and Pressure chart. If the temperature reading is high, clamp off both heater hoses (inlet and outlet), wait five minutes and record the temperature again. Compare the second reading to the Performance Temperature and Pressure chart. If the temperature reading is now OK, see Temperature Control Cable in the Removal and Installation section and in the Adjustments section of this group. If the temperature reading is still too high, see Refrigerant System Leaks in the Diagnosis and Testing section of this group, and Refrigerant System Charge in the Service Procedures section of this group.
Performance Temperature and Pressure
Ambient Temperature21° C(70° F)27° C(80° F)32° C(90° F)38° C(100° F)43° C(110° F)49° C(120° F)
Center Panel OutletDischarge Air Temperature 5 to 7° C(40 to 45° F)13 to 16° C(55 to 60° F)16 to 21° C(60 to 70° F)21 to 24° C(70 to 75° F)27 to 29° C(80 to 85° F)29 to 32° C(85 to 90° F)
*Suction Pressure (Low Side)241 to 276 kPa(35 to 40 psi)276 to 345 kPa(40 to 50 psi)345 to 414 kPa(50 to 60 psi)414 to 483 kPa(60 to 70 psi)483 to 552 kPa(70 to 80 psi)552 to 586 kPa(85 to 90 psi)
*Discharge Pressure (High Side)931 to 1000 kPa(135 to 145 psi)1207 to 1482 kPa(175 to 215 psi)1482 to 1862 kPa(215 to 270 psi)1862 to 2275 kPa(270 to 330 psi)2344 to 2551 kPa(340 to 370 psi)2758 to 2965 kPa(400 to 430 psi)
*Note: If pressures are lower than shown, but center panel outlet discharge air temperatures are OK, then the A/C system is OK..
9.Compare the discharge (high side) and suction (low side) pressure readings to the Performance Temperature and Pressure chart. If the pressures are abnormal, see the A/C Diagnosis chart in the Diagnosis and Testing section of this group.
A/C Diagnosis
ConditionPossible CausesCorrection
RAPID COMPRESSOR CLUTCH CYCLING (TEN OR MORE CYCLES PER MINUTE)1. Low refrigerant system charge.2. Faulty low pressure cycling clutch switch.3. Faulty Powertrain Control Module (PCM)1. See Refrigerant System Leaks in the Diagnosis and Testing section of this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.2. See Low Pressure Cycling Clutch Switch in the Diagnosis and Testing section of this group. Test the low pressure cycling clutch switch and replace, if required.3. Refer to the proper Diagnostic Procedures manual for testing of the PCM. Test the PCM and replace, if required.
EQUAL PRESSURES, BUT THE COMPRESSOR CLUTCH DOES NOT ENGAGE.1. No refrigerant in the refrigerant system.2. Faulty fuse.3. Faulty compressor clutch coil.4. Faulty compressor clutch relay.5. Improperly installed or faulty low pressure cycling clutch switch.6. Faulty high pressure cut-off switch.7. Faulty Powertrain Control Module (PCM)8. Faulty heater-A/C control.1. See Refrigerant System Leaks in the Diagnosis and Testing section of this group. Test the refrigerant system for leaks. Repair, evacuate and charge the refrigerant system, if required.2. Check the fuses in the Power Distribution Center and the junction block. Repair the shorted circuit or component and replace the fuses, if required. 3. See Compressor Clutch Coil in the Diagnosis and Testing section of this group. Test the compressor clutch coil and replace, if required.4. See Compressor Clutch Relay in the Diagnosis and Testing section of this group. Test the compressor clutch relay and relay circuits. Repair the circuits or replace the relay, if required.5. See Low Pressure Cycling Clutch Switch in the Diagnosis and Testing section of this group. Test the low pressure cycling clutch switch and tighten or replace, if required.6. See High Pressure Cut-Off Switch in the Diagnosis and Testing section of this group. Test the high pressure cut-off switch and replace, if required.7. Refer to the proper Diagnostic Procedures manual for testing of the PCM. Test the PCM and replace, if required.8. See Heater-A/C Control in the Diagnosis and Testing section of this group. Test the heater-A/C control and replace, if required.
NORMAL PRESSURES, BUT A/C PERFORMANCE TEST AIR TEMPERATURES AT CENTER PANEL OUTLET ARE TOO HIGH. 1. Excessive refrigerant oil in system.2. Temperature control cable improperly installed or faulty.3. Blend-air door inoperative, obstructed or sealing improperly. 1. See Refrigerant Oil Level in the Service Procedures section of this group. Recover the refrigerant from the refrigerant system and inspect the refrigerant oil content. Restore the refrigerant oil to the proper level, if required.2. See Temperature Control Cable in the Removal and Installation and Adjustments sections of this group. Inspect the temperature control cable for proper routing, operation and adjustment. Repair as required.3. See Heater-A/C Housing Door in the Removal and Installation section of this group. Inspect the blend-air door for proper operation and sealing and correct, if required.
LOW SIDE PRESSURE IS NORMAL OR SLIGHTLY LOW, AND HIGH SIDE PRESSURE IS TOO LOW.1. Low refrigerant system charge.2. Refrigerant flow through the accumulator is restricted.3. Refrigerant flow through the evaporator coil is restricted. 4. Faulty compressor. the numbers above are in a chart form and not read across.

Edited by weitz70 on August 9 2006 at 5:38 PM

ok based on that reading the system is either low(is your recharge machine accurate) or the compressor is not working correctly. those are the two most common problems anyway.I assume that when the comp shuts off that the low side press is going to 20 psi and the low side switch is cutting the comp out.LOW SIDE PRESSURE IS NORMAL OR SLIGHTLY LOW, AND HIGH SIDE PRESSURE IS TOO LOW.1. Low refrigerant system charge.2. Refrigerant flow through the accumulator is restricted.3. Refrigerant flow through the evaporator coil is restricted.

ok here is what i would do. if this truck came into the shop with those pressure readings then i would reclaim the system to see how much r134 was in it. if low I would check for leaks and refill.if it was full then I would remove the ac lines from the comp and evap and blow shop air through them to check if they were blocked(Of course you had replaced the accum and or-valve).I am guessing that you have one of these wrong, tipicaly if the compressor is bad the low side is ok and the high side just doesnt go up. and the comp tipicaly wont cycle because it does not pull the low side down below 20psi. Please keep in mind that diagnosing a car this way can be difficult, and offten times without being able to see the car i cant give you a definate cause. I do my best to give you possible causes and/or tests to run based on my experiance and the synptoms/facts you give me.and all of this is limmited by my interpritation and your skill.(Im not trying to sound like an A****** just telling it like it is).If your system is full and you say that there is no restriction then about the only thing left is the compressor,and i dont belive that to be the case based on the rapid cyling of the comp.do you have acces to a ac machine that tells how much 134 is reclaimed? if the system is full and when the comp comes on the low side spikes low and shuts off then there must be a restriction from the or-valve to the comp.let me know,how much is in it in lbs and ounces and when it is full how does the low and high side act when the comp comes on(quick jumps or slow)

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