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Hybrid vehicle A/C compressor

 




HVAC systems differ from one hybrid to the next, and some systems, such as those on Honda and Toyota Prius 2001-’03 models have used a scroll compressor, which can be powered via a belt when the engine is running, or electrically when the engine is off. Most of the newer hybrids have changed to an inverter compressor, which is a high-voltage electrical motor. The motor runs on high-voltage AC supplied by the A/C inverter ­located in the inverter or affixed to the A/C compressor itself, so compressor operation does not depend on the engine.

The electric compressor consists of a spirally wound fixed scroll and variable scroll with a brushless motor. These systems use a special high insulation for compressor lubrication. The compressors are a wet sump type with the armature submerged in oil for lubrication and cooling. Oil-based florescent dye should not be added to electrical compressor systems due to electrical conductivity.

Leak detection dye, when used in the proper quantity, will not harm air conditioning components or those working with it. If a vehicle was manufactured with leak detection dye, adding more is not necessary, unless prior air conditioning system flushing or multiple refrigerant ­component replacement caused the dye to be removed from the system.

Leak detection dye

There is a specific dye for hybrid electric vehicles that use R-134a in the air conditioning system equipped with an electric compressor. Hybrid electric vehicle leak detection dye is polyolester based and is specific to hybrid electric vehicles.

The R-134a leak dye used for non-hybrid electric vehicles uses PAG oil, which is hygroscopic. Using it in a hybrid vehicle, even in the smallest amount, can create an air conditioning compressor failure. The oil in the dye breaks down the insulating properties of the windings on the electric motor portion of the compressor. These windings are immersed in compressor oil, and ester oil is used to protect the insulation on the windings to prevent electrical leakage. The addition of PAG oil into a hybrid air ­conditioning system designed for ester oil may result in an air conditioning ­system malfunction.

Additionally, in hybrid vehicles with an electric compressor, when a dye containing a lubricant other than ester oil is added to the air conditioning system, it contaminates the air conditioning system. Flushing the system must be performed to remove the dye. In fact, because of the contamination concern with dye, Honda does not approve its use in hybrid vehicles. Toyota does not recommend dye for any of its air conditioning systems.

Hybrid compressor dos and don’ts

Dos

Do use PAG 46 oil or equivalent on first-­generation 2001-’03 Prius.


Do use PAG 46 oil or equivalent on 2000-’06 Insight and 2005 Civic.


Do always refer to manufacturers’ recommendations when servicing A/C systems.


Do shut down high-voltage battery power when servicing any high-voltage A/C compressor.


Don’ts

Do not use any compressor oil other than ND-11 or equivalent on Toyotas.


Do not use PAG oil on vehicles with HV compressors.


Do not use any compressor oil other than ­SE-10Y or equivalent on Hondas.


Do not use any compressor oil other than what’s recommended by the manufacturer.


Do not use safety or test equipment on high-voltage systems unless they’re tested or certified for use on high-voltage systems.


Do not flush high-voltage systems.


Courtesy of Delphi Product & Service Solutions

Generic Codes

P1246: Alternator load input failed

Meaning

The powertrain control module monitors generator load from the generator/regulator in the form of frequency. The frequency range is determined by the temperature of the voltage regulator where 97 per cent represents full load, below six per cent means no load.

Possible causes

Faulty alternator/generator


Alternator/generator harness is open or shorted


Alternator/generator circuit poor electrical connection


Damaged powertrain control module


P1247: Turbo boost pressure low

Meaning

The boost pressure sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with accelerator pedal position and engine speed. The powertrain control module uses this information to assist in diagnosis of the barometric pressure sensor and to provide engine overboost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost pressure sensor provides a signal to the PCM on a signal circuit relative to the pressure changes. The PCM monitors the boost pressure sensor signal for voltage outside of the normal range. The PCM calculates a predicted value for the boost pressure sensor. The PCM then compares the predicted value to the actual signal.

Possible causes

Damaged MAP hose


Low turbo boost


Intake manifold or crossover tube hose leaks


Faulty MAP sensor


Faulty powertrain control module


P1248: Turbo boost pressure not detected

Meaning

The boost pressure sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with accelerator pedal position and engine speed. The powertrain control module uses this information to assist in diagnosis of the barometric pressure sensor and to provide engine overboost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost pressure sensor provides a signal to the PCM on a signal circuit relative to the pressure changes. The PCM monitors the boost pressure sensor signal for voltage outside of the normal range. The PCM calculates a predicted value for the boost pressure sensor. The PCM then compares the predicted value to the actual signal.

Possible causes

Damaged MAP hose


Low turbo boost


Intake manifold or crossover tube hose leaks


Faulty MAP sensor


Faulty powertrain control module


P1249: Injector 2 positive voltage control circuit shorted to control circuit

Meaning

The engine control module supplies voltage to each fuel injector on the injector high voltage supply circuits. The ECM energises each fuel injector by grounding the high voltage control circuit of the fuel injector. The ECM monitors the status of the injector high voltage supply circuits and the fuel injector high voltage control circuits. When a fuel injector circuit condition is detected by the ECM, the affected fuel injector(s) is disabled. The diagnostic trouble code will be set if the ECM detects the injector high control circuit is shorted to the low control circuit for greater than 2s.

Possible causes

Faulty Fuel Injector 2


Fuel Injector 2 harness is open or shorted


Fuel Injector 2 circuit poor electrical connection


P1250: Fuel pressure regulator control solenoid valve circuit malfunction

Meaning

The powertrain control module monitors the fuel pressure regulator control solenoid valve. The PCM sets the diagnostic trouble code when the fuel pressure regulator control solenoid valve is not to factory specifications.

Possible causes

Faulty fuel pressure regulator control solenoid valve


Fuel pressure regulator control solenoid valve harness is open or shorted


Fuel pressure regulator control solenoid valve circuit poor electrical connection.(Punch)




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