How to Service Air Conditioners on Hybrid Vehicles

Service Hybrid Vehicle's A/C

 

First Things First

It is very important to recognize the differences between conventional and electric compressor A/C systems, obtain the proper training, the required equipment, and use the specified refrigerant oils to ensure the complete, safe, and quality repairs to these A/C systems.

 

Hybrid Vehicle A/C Compressors

Hybrid Electric Vehicles Electric A/C compressors use the high voltage from the hybrid battery pack to operate the compressor. The high voltage DC from the battery pack is converted to 3 phase AC voltage to operate the motor inside the A/C compressor. Sometimes the inverter/converter module is inside the compressor, fed by 2 high voltage wires, and sometimes it is outside the compressor, feed by 3 high voltage wires.

 

How to Stay Safe Servicing Hybrid Vehicle A/C Systems

DO NOT attempt to service a hybrid vehicle A/C system without getting the proper training first! Knowing what can kill you and what personal protective equipment to use to prevent that is important. Orange cables going to the compressor indicates you will need High Voltage gloves and a CAT III 1000 Voltmeter to prove the system is disabled before disassembling.

Be sure to read our article about safely diagnosing and working on hybrids.

 

Hybrid A/C System’s Refrigerant Oil

Electric compressors require non-conductive Polyol Ester (POE) refrigerant oil. There are several manufacturers of POE oils, they are not the same. Only use the manufactures specified refrigerant oil. It is also recommended to use a separate machine and flush the lines between vehicles to prevent oil contamination.

A PAG oil contamination of 1% can reduce the insulating property from 10 Megaohms to under 1 megaohm, potentially setting isolation fault codes.

Leak detection die should NOT be used in systems with electric compressors. UV dies most often contain PAG oil and/or solvents. PAG oils reduce the insolation properties of the oil and solvents are flammable.

Most manufactures require a complete system/all components replacement for contamination.

Recovery/ recycling/ recharge (RRR) machines that meet SAE specification J2788H are acceptable for use on hybrid vehicles with electrically driven compressors. These RRR machines are designed to prevent a harmful amount of oil from mixing with the refrigerant during charging.

 

A Few Other Notes

Sun load sensors do make a difference in operational characteristics. If you are diagnosing a performance complaint, you will want to test the system outside with a strong sun load.

The “ECON” button also makes a large difference in the operational characteristics. The acceptable outlet temperature with “ECON” on can be 10 to 20 degrees higher than in “MAX A/C”.

 

Some Tools You’ll Need for Diagnosis

You will need to have Bidirectional control and complete data PIDs to diagnose a Hybrid Vehicle’s A/C performance issues. Electrically powered compressors vary compressor RPM to modulate the compressor volume. The pressures on a gauge set will look the same as other R134 systems; high 20’s to low 30’s on the low-pressure side and 200 to 300 on the high side.

Finally, you’ll also need a good repair information source.

 

Further Learning

Now that you’ve got the basics you can start diving more into the world of Hybrid Vehicle A/C systems. Check out these resources below for additional learning and training.

www.macsw.org 

www.Fueleconomy.gov 

www.greencarcongress.com 

www.edmunds.com/ford/escape-hybrid/2010/ 

www.hybridcars.com 

www.sae.org/events/aars/presentations/2004-ishikawa.pdf 

www.nrdc.org/energy/vehicles/hybrid.asp