CHART 1, NO COMPRESSOR OPERATION
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
Compressor clutch coil is fed power through A/C relay and is grounded through A/C ground (circuit No. 804).
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step checks if fault lies in output or input side of PCM.
2) This step checks A/C relay switch contacts.
3) This step checks if A/C relay is receiving power on circuit No. 258.
4) This step checks if an open exists in compressor clutch power circuit No. 59.
5) This step checks if compressor clutch is faulty or if an open exists in compressor clutch ground circuit No. 804.
6) This step checks A/C relay coil.
7) This step checks if an open exists in circuit No. 67 or 762 which prevents A/C relay from closing.
Scheme 9
Scheme 10
CHART 2, NO BLOWER OPERATION
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
Programmer sends a variable voltage signal to power module which is then amplified and sent to blower motor. Programmer monitors blower feedback voltage so signal can be adjusted to achieve desired blower motor speed.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step checks if power module is receiving a voltage signal from programmer.
2) This step checks power module ground circuit.
3) This step checks power module voltage supply circuit.
4) This step checks to see if blower motor is receiving voltage from power module.
5) This step checks blower motor ground circuit.
Scheme 11
Scheme 12
CHART 3, IMPROPER BLOWER SPEED
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
Programmer sends a variable voltage signal to power module which is then amplified and sent to blower motor. Programmer monitors blower feedback voltage so signal can be adjusted to achieve desired blower motor speed.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step categorizes problem as short to voltage on blower control or feedback circuit, open feedback signal or inaccurate/improper sensor input.
2) This step checks for a short to voltage on circuit No. 754.
3) This step checks for a short to voltage on circuit No. 65.
4) This step checks for an open or short to ground in circuit No. 65.
Scheme 13
CHART 4, IMPROPER AIR DELIVERY
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
ACP will direct blended air in one of several air delivery modes. While side window outlets receive airflow during all modes of operation, other outlets are directed air by ACP energizing specific vacuum valves feeding appropriate combination of mode valve actuators. ACP determines proper air delivery mode based upon current program number, control panel setting, set temperature, low-side temperature, coolant temperature, outside air temperature and sunload.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step checks air inlet valve (door).
2) Checks down part of up-down valve (door).
3) Checks up part of up-down valve (door).
4) Checks A/C side of A/C-defrost valve (door).
5) Checks defrost side of A/C-defrost valve (door).
Scheme 14
Scheme 15
CHART 5, IMPROPER TEMPERATURE CONTROL
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
Verify customer complaint as compared to another 1993 Eldorado or Seville prior to attempting diagnosis.
Given driver-selected set temperature, ACP uses inside air temperature sensor (AD25) to determine if interior of vehicle requires heating or cooling to achieve and maintain selected comfort level. ACP monitors outside temperature sensor (AD26), solar sensor (AD32) and coolant temperature (AD21) to determine required air-mix door position, blower speed and air delivery mode.
Note. Test numbers refer to test numbers on diagnostic chart.
1) Checks if heater system has sufficient heating capacity.
2) Checks if refrigerant system has sufficient cooling capacity.
3) Checks if solar sensor reacts correctly to a no light condition.
4) Checks if either solar sensor or power circuit No. 590 is causing incorrect reading.
5) Checks if solar sensor reacts correctly to a bright light condition.
6) Checks if either solar sensor, sensor alignment to I/P opening or ground circuit No. 736 is causing incorrect reading.
7) Checks if outside temperature sensor is providing an accurate temperature reading.
8) Checks if incorrect reading is caused by high resistance or a short to ground in power circuit No. 735.
9) Checks if either outside temperature sensor or circuit No. 736 is causing incorrect reading.
10) Checks if a component or 'build' condition is causing inside air temperature sensor to have incorrect reading.
11) Checks if incorrect reading is caused by high resistance or a short to ground in power circuit No. 734.
12) Checks if inside air temperature sensor, its connectors, alignment within housing or ground circuit No. 736 is causing incorrect reading.
Scheme 16
Scheme 17
CHART 6, REAR DEFOGGER ON CONTINUOUSLY
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
ACP provides a ground for defogger relay when it receives a command from IPC via data line. IPC times operation initially for 10 minutes, and then commands programmer to deactivate relay ground. Additional requests for rear defogger are for 5 minute intervals until a new ignition cycle occurs. For information on grid pattern, see appropriate REAR WINDOW DEFOGGER article in the ACCESSORIES/SAFETY EQUIPMENT Section.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step eliminates a short to voltage on circuit No. 840, 293 or 676.
2) This step checks relay coil resistance. Diminished resistance may be caused by a faulty ACP.
3) This step distinguishes between a short to ground on circuit 291 and a faulty ACP.
Scheme 18
Scheme 19
CHART 7, REAR DEFOGGER INOPERATIVE
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
ACP provides a ground for defogger relay when it receives a command from IPC via data line. IPC times operation initially for 10 minutes, and then commands programmer to deactivate relay ground. Additional requests for rear defogger are for 5 minute intervals until a new ignition cycle occurs.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step checks if rear defogger relay is receiving power.
2) This step checks rear defogger relay for proper operation.
3) This step decides between an open in power source or an open in ground.
Scheme 20
CHART 8, REAR A/C BLOWER SPEED INCORRECT
Power from fuse is applied to blower and ground is supplied through switch. Blower speed is controlled by varying circuit amperage using a series of three resistors contained in a module. ACP receives a feedback signal but has no bearing on rear blower operation.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step checks for poor ground or poor feed circuit.
2) This step determines if resistor module is faulty.
3) This step defines a faulty circuit or faulty switch assembly.
Scheme 21
Scheme 22
CHART 9, REAR A/C BLOWER INOPERATIVE
Power from fuse is applied to blower and ground is supplied through switch. Blower speed is controlled by varying circuit amperage using a series of three resistors contained in a module. ACP receives a feedback signal but has no bearing on rear blower operation.
Note. Test numbers refer to test numbers on diagnostic chart.
1) This step determines if a fuse is blown due to excessive draw of blower motor.
2) This step looks for an open in resistor module or a faulty connection.
3) This step checks for an open circuit to switch assembly.
4) This step checks ground to switch assembly.
Scheme 23
CHART 10, REFRIGERANT SYSTEM CHECK
Note. Perform ECC SYSTEM CHECK before proceeding with this test. See TROUBLE SHOOTING in AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.
Before performing REFRIGERANT SYSTEM CHECK, check for restricted airflow at condenser and ensure ambient temperature is greater than 50°F (10°C).
Scheme 24
ACP CODE A010, OUTSIDE TEMPERATURE SENSOR CIRCUIT
Note. If ambient temperature drops below approximately -36°F(-38°C), this code should be ignored.
Outside air temperature sensor is a thermistor which controls signal voltage to ACP. ACP applies a voltage on circuit No. 735 to sensor. When sensor is cold, its resistance is high; therefore, ACP will see a high signal voltage at pin D8. As sensor warms, its resistance decreases and signal voltage is pulled low through sensor ground circuit No. 736. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).
Test Conditions
Ignition on.
Failure Conditions
Signal voltages indicating less than -38°F (-39°C) for an open circuit or equal to 127°F (53°C) for a short circuit.
Actions Taken
- Display "--" on IPC temperature display.
- A substitute temperature reading will be implemented to allow operation of climate control system (AD26 will display actual sensor reading).
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP data value AD26 displays outside temperature. Valid operating range is from -36° to 126°F (-38° to 52°C).
2) A reading too low indicates an open circuit. Jumpering harness connector will determine whether wiring or sensor is cause of open.
3) A reading too high indicates a short circuit. Removing sensor will determine whether wiring or sensor is cause of short.
4) Open has been determined to be in wiring. Providing a ground at jumper will determine if open is in ground wiring or sensing wire.
5) Grounding connector at ACP will determine if open is in sense circuit, at ACP connection or in ACP itself.
6) Grounding connector at ACP will determine if open is in ground circuit, at ACP connection or in ACP itself. Note values of AD25, AD26, AD27 and AD28. If all read near -40, repair open circuit No. 736 between ACP and C201 "M". If AD25 and AD26 read near -40, repair open circuit No. 736 between C201 "M" and S219. If only AD26 reads near -40, repair open circuit No. 736 between S219 and outside air temperature sensor.
Note On Intermittents
If an intermittent code A010 is being set, select ACP SNAPSHOT DATA for Code A010 and note value of AD26. A reading of approximately -40 indicates an intermittent open and a reading of 53 indicates an intermittent short.
Manipulate related wiring while observing ACP data value AD26. If failure is induced, reading will jump outside its normal range. If value displayed by AD26 is not reasonably close to actual temperature of air at sensor, check for poor terminal contact, obstructed sensor or defective sensor.
Scheme 25
Scheme 26
ACP CODE A011, HIGH-SIDE TEMPERATURE SENSOR CIRCUIT
High-side temperature sensor is a thermistor which controls a signal voltage to ACP. ACP applies a voltage on circuit No. 732 to sensor. When sensor is cold, its resistance is high; therefore, ACP will see a high signal voltage at pin D14. As sensor warms, its resistance decreases and signal voltage is pulled low through sensor ground circuit No. 736. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).
- Ignition on.
- Code A010 not set.
- Temperature is greater than 30°F (1°C). For later production models only, AD99 is not equal to 8640.
Signal voltages indicating less than -0.4°F (-18°C) for an open circuit or greater than 354°F (179°C) for a short circuit calibrated.
High coolant fan operation when A/C compressor operation possible.
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP data value AD27 displays high-side temperature. Valid operating range is from -0.4° to 354°F (-18° to 179°C).
2) A reading too low indicates an open circuit. Jumpering harness connector will determine whether wiring or sensor is cause of open.
3) A reading too high indicates a short circuit. Removing sensor will determine whether wiring or sensor is cause of short.
4) Open has been determined to be in wiring. Providing a ground at jumper will determine if open is in ground wiring or sensing wire.
5) Grounding connector at ACP will determine if open is in sense circuit, at ACP connection or in ACP itself.
6) Note values of AD25, AD26, AD27 and AD28. If all values are near -40, repair open circuit No. 736 between ACP and C201 "M". If AD27 and AD28 read near -40, repair open circuit No. 736 between C201 "M" and S218. If only AD27 reads near -40, repair open circuit No. 736 between S218 and high-side sensor.
On some early production vehicles (AD99 is 1847), this code may set intermittently if sensor temperature falls below 30°F (1°C). Code becomes history after sensor temperature increases. If an intermittent code A011 is being set, select ACP SNAPSHOT DATA for Code A011 and note value of AD27. A reading of approximately -38 indicates an intermittent open and a reading above 179 indicates an intermittent short.
Manipulate related wiring while observing ACP data AD27. If failure is induced, reading will jump outside its normal range.
Scheme 27
ACP CODE A012, LOW-SIDE TEMPERATURE SENSOR CIRCUIT
Low-side temperature sensor is a thermistor which controls a signal voltage to ACP. ACP applies a voltage on circuit No. 731 to sensor. When sensor is cold, its resistance is high; therefore, ACP will see a high signal voltage at pin D15. As sensor warms, its resistance decreases and signal voltage is pulled low through sensor ground circuit No. 736. This signal voltage will vary between 5 volts for an open circuit and zero volts for a short circuit.
Ignition on.
Signal voltages indicating less than -36°F (-38°C) for an open circuit or greater than 199°F (93°C) for a short circuit.
- A/C compressor not allowed to engage. IPC will display SERVICE A/C SYSTEM - A/C COMPRESSOR OFF.
- A substitute temperature reading (filtered outside temperature) will be implemented. AD28 will display actual sensor reading.
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP data value AD28 displays low side temperature. Valid operating range is -36° to 199°F (-38° to 93°C).
2) A reading too low indicates an open circuit. Jumpering harness connector will determine whether wiring or sensor is cause of open.
3) A reading too high indicates a short circuit. Removing sensor will determine whether wiring or sensor is cause of short.
4) Open has been determined to be in wiring. Providing a ground at jumper will determine if open is in ground wiring or sensing wire.
5) Grounding connector at ACP will determine if open is in sense circuit, at ACP connection or in ACP itself.
6) Note values of AD25, AD26, AD27 and AD28. If all values are near -40, repair open circuit No. 736 between ACP and C201 "M". If AD27 and AD28 read near -40, repair open circuit No. 736 between C201 "M" and S218. If only AD28 reads near -40, repair open circuit No. 736 between S218 and low-side sensor.
If an intermittent code A012 is being set, select ACP SNAPSHOT DATA for Code A012 and note value of AD28. A reading of approximately -40 indicates an intermittent open; a reading above 93 indicates an intermittent short.
Manipulate related wiring while observing ACP data value AD28. If failure is induced, reading will jump outside its normal range. If value of sensor, displayed by AD28, is not reasonably close to corresponding gauge pressure reading, check for poor terminal contact or replace sensor.
Scheme 28
ACP CODE A013, IN-CAR TEMPERATURE SENSOR CIRCUIT
In-car temperature sensor is a thermistor which controls signal voltage to ACP. ACP applies a voltage on circuit No. 734 to sensor. When sensor is cold, its resistance is high; therefore, ACP will see a high signal voltage. As sensor warms, its resistance decreases and signal voltage is pulled low through sensor ground circuit No. 736. This signal voltage will vary between 5 volts for an open circuit and zero volts for a short circuit.
- Ignition on.
- Outside air temperature reads above -20°F (-29°C).
Signal voltages indicating less than -29°F (-34°C) for an open circuit or greater than 210°F (99°C) for a short circuit.
- A substitute temperature reading will be used to allow continued climate control operation.
- In-car temperature reading AD25 will display actual sensor reading.
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP data value AD25 displays in-car temperature. Valid operating range is -29° to 210°F (-34° to 99°C).
2) A reading too low indicates an open circuit. Jumpering harness connector will determine whether wiring or sensor is cause of open.
3) A reading too high indicates a short circuit. Removing sensor will determine whether wiring or sensor is cause of short.
4) Open has been determined to be in wiring. Providing a ground at jumper will determine if open is in ground wiring or sensing wire.
5) Grounding connector at ACP will determine if open is in sense circuit, at ACP connection or in ACP itself.
6) Note values of AD25, AD26, AD27 and AD28. If all values are near -40, repair open circuit No. 736 between ACP and C201 "M". If AD25 and AD26 read near -40, repair open circuit No. 736 between C201 "M" and S219. If only AD25 reads near -40, repair open circuit No. 736 between S219 and in-car sensor.
On some early production vehicles (AD99 is 1847), this code may set intermittently if sensor temperature falls below -20°F (-28°C). Code will become history code after sensor temperature increases.
If an intermittent code A013 is being set, select ACP SNAPSHOT DATA for Code A010 and note value of AD25. A reading of approximately -40 indicates an intermittent open and a reading above 99 indicates an intermittent short.
Manipulate related wiring while observing ACP data AD25. If failure is induced, reading will jump outside its normal range. If value displayed by AD25 is not reasonably close to actual temperature of air at sensor, check for proper terminal contact and proper airflow across sensor or replace sensor.
Scheme 29
ACP CODE A015, SUNLOAD SENSOR CIRCUIT
Sunload sensor uses a light sensitive photodiode to control a signal voltage to ACP. This photodiode is different from standard thermistor type sensors and resistance measurements will not produce accurate results. ACP monitors voltage on circuit No. 590 to sensor. When sensor is in direct light, ACP will see a low signal voltage. As sensor becomes shaded, signal voltage increases. This signal voltage varies between 5 volts for an open circuit and zero volts for a short circuit.
Ignition on.
Signal voltages indicating less than 2 percent for a short circuit or greater than 98 percent for an open circuit.
- A substitute reading (98 percent) will be implemented to allow continued operation of climate control system.
- Sunload temperature reading AD32 will display actual sensor reading.
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP data value AD32 displays sunload reading. Normal range is 2-98 percent.
2) A reading too low indicates a short circuit. Removing sensor will determine whether wiring or sensor is cause of short.
3) A reading too high indicates an open circuit. Jumpering harness will determine whether wiring or sensor is cause of open.
4) Open has been determined to be in wiring. Providing a ground at jumper will determine if open is in ground wiring or sensing wire.
5) Grounding connector at ACP will determine if open is in sense circuit, at ACP connection or in ACP itself.
6) If A015 is set without A013, look for an open circuit No. 736 between S219 and sensor. An open anywhere else in circuit should set at least A013 as well.
If an intermittent code A015 is being set, select ACP SNAPSHOT DATA for Code A015 and note value of AD32. A reading of approximately 98 percent indicates an intermittent open and a reading below 2 percent indicates an intermittent short.
Manipulate related wiring while observing ACP data AD32. If failure is induced, reading will jump outside its normal range.
Scheme 30
ACP CODE A037, LOSS OF IPC DATA
Code A037 will set if ignition is on and ACP has lost data communication with IPC. This code should be seen only as a history code. If communications are currently inoperative, ACP will not be able to communicate with IPC to display trouble code. Diagnosis of this code is dependent upon other system symptoms (trouble codes) present with A037.
A037 & I037
If Code I037 (Loss of ACP Data) is present, IPC and ACP were both functional when code set but could not communicate with one another. For this condition, refer to diagnostic chart for Multiple Data Communications Codes in ELECTRONIC INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT Section.
A037, I052 & E047
If Code I052 (IPC Loss of Memory) is present, IPC experienced a memory reset condition (lost battery or battery power was interrupted in some other way) and temporarily quit communicating with other major computers. If this combination is present, code E047 (Loss of IPC Data) may also be stored in history. Refer to diagnostic chart for I052. See ELECTRONIC INSTRUMENT PANEL article in the ACCESSORIES/SAFETY EQUIPMENT Section.
Scheme 31
ACP CODE A040, AIR-MIX VALVE (DOOR) CIRCUIT PROBLEM
ACP supplies voltage to an internal motor which drives air-mix door. ACP monitors mix door position feedback from a sensor on motor. If mix door is requested to move but feedback voltage does not change, ACP stores code A040. If air-mix door feedback indicates it is near hot or cold extreme, code will not set. Operation of air-mix door can be evaluated through self-diagnostics as described in test number 1) below.
- Commanded mix door greater than zero percent.
- Commanded mix door less than 76 percent.
Actual mix door position not within 3 percent of commanded mix door position within approximately 60 seconds.
None.
Note. Test numbers refer to test numbers on diagnostic chart.
1) ACP override AS12 allows for direct control of HVAC mix door with WARM/COOL buttons. CCC will display current commanded air-mix door position as a value between 1 and 99. After selecting AS12, pressing OFF will allow for selection of a new test type. Selecting DATA and then AD23 will enable technician to command air-mix door to any position (via WARM/COOL buttons) and observe air-mix door position sensor feedback (AD23) and its difference from air-mix door commanded position (AD22).
2) These readings indicate a fault, internal to ACP, in air-mix door sensor feedback.
3) If door is not stuck, ensure smooth operation before replacing ACP.
If an intermittent code A040 is being set, select ACP SNAPSHOT DATA for Code A040 and note value of AD22 and AD23. Using override AS12 while monitoring AD23, command door to these positions. Without keying off, physically inspect mix door linkage for any obstruction at these positions.
Scheme 32
Scheme 33
ACP CODES A046 & A047, LOW REFRIGERANT CHARGE
In process of controlling compressor clutch, ACP monitors certain inputs for an indication of low refrigerant charge. If system refrigerant charge should fall below approximately one third its capacity, ACP is capable of detecting this condition and will display a driver warning message to warn operator.
ACP determines state of charge by monitoring temperature change in low-side temperature sensor during initial moments of each compressor engagement. This temperature drop is referenced in a table in ACP as a function of outside air temperature. If refrigerant charge is too low, refrigerant will boil instantaneously after it passes through orifice tube, creating a rapid and large change in low-side temperature reading. If temperature change is too great, a low and/or very low refrigerant counter in ACP is increased one increment. Once counter has reached a calibration value, a LOW (A046) or VERY LOW (A047) refrigerant level is determined and displayed to driver. If an A047 is detected, compressor clutch will disengage and remain disengaged until diagnostic codes are cleared.
- A046 (Low Refrigerant Warning) will set if low-side refrigerant temperature drops too quickly during several compressor cycles.
- A047 (Very Low Refrigerant Warning) will set if low-side refrigerant temperature drops much too quickly during several compressor cycles or low refrigerant pressure switch opens during several compressor cycles.
- A046 displays LOW A/C REFRIGERANT - SERVICE A/C SOON message on DIC.
- A047 displays VERY LOW REFRIGERANT - A/C COMPRESSOR OFF message on DIC. Disable compressor until diagnostic codes are cleared. NOTE: Test numbers refer to test numbers on diagnostic chart. 1) Check for intermittent open or short in pressure switch circuit. 2) Checks for restriction causing intermittent low pressure condition. 3) Checks for restriction within refrigerant system. 4) An offset in ACP temperature sensors AD26 actual outside or AD28 low-side may trigger a false code. After leaving vehicle, preferably overnight, in a shaded, cold environment, enter diagnostics without starting engine. All listed sensor readings should agree with 37°F (2°C).
Scheme 34
Scheme 35
ACP CODE A048, LOW REFRIGERANT PRESSURE
In process of controlling compressor clutch, ACP monitors certain system inputs for an indication of low refrigerant charge. ACP monitors normally closed low refrigerant pressure switch at pin C3. Status of low pressure switch is checked before compressor engagement. If return voltage to ACP indicates switch is open, compressor will not be allowed to engage and a code A048 will be set in memory. Additionally, ECC will switch to ECON mode and A/C LOW REFRIGERANT message will be displayed.
A048 (Very Low Refrigerant Pressure Condition) will set if low refrigerant pressure switch remains open for several minutes.
Action Taken
A048 display VERY LOW REFRIGERANT - A/C COMPRESSOR OFF message on DIC. Disable compressor until diagnostic codes are cleared.
Note. Test numbers refer to test numbers on diagnostic chart.
1) Checks current state of low pressure switch.
2) Checks circuits to low pressure switch.
3) Checks refrigerant system pressure.
4) Checks for restriction in refrigerant system.
5) Checks for intermittent short/open.
Scheme 36
ACP CODE A049, HVAC - HIGH-SIDE TEMPERATURE TOO HIGH
Code A049 is designed to disengage A/C compressor clutch if high-side refrigerant temperature (ACP data parameter AD27) exceeds 199°F (93°C) calibrated. A/C compressor will re-engage and code will be stored as a history code when high-side temperature falls below 189°F (87°C) calibrated. If code A049 has been set, possible causes for excessive high A/C head pressure, including cooling fan operation, must be checked.
Scheme 37
ACP CODE A050, HVAC - COOLANT TEMPERATURE TOO HIGH
Code A050 is designed to disengage A/C compressor clutch if coolant temperature (ACP data parameter AD21) exceeds 258°F (126°C). Once code has been set, it will remain current until coolant temperature falls below 240°F (116°C). ACP receives coolant temperature information from PCM over serial data. While A050 is current, IPC will display ENGINE HOT - A/C COMPRESSOR OFF warning.
ACP CODE A052, KEEP ALIVE MEMORY ERROR (EARLY PRODUCTION ONLY - AD99 = 1847)
Note. This code is only present on early production vehicles (ACP Software ID, AD99, equal to 1847).
Code A052 indicates keep alive or long-term memory in ACP has been reset, normally whenever battery or ground has been removed from ACP, such as anytime battery has been removed and reconnected. If Code A052 continues to reset, check for good connections/wiring at terminals C13 and C1 (battery and ground).
