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Dave Nova
Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 19450
Experience:  ASE Master Certification. GM World Class Certification
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GM silverado: Hello. I have a 2000 chev. silverado 5.3L. My

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Hello. I have a 2000 chev. silverado 5.3L. My question is; Why am i loosing power to a/c comp. relay when vehicle is in motion? When its in park or in drive with no vehicle motion the a/c relay remains powered.
Hello and thank you for trusting me with your question. My name is XXXXX XXXXX I will do my best to help you with your GMC problem.

Does the compressor cycle on and off while driving, or does it cycle off and stay off?

Customer: replied 3 years ago.

Sorry i forgot to mention, It does cycle on and off while in motion. Remains on while standing.


The system will cool better with the vehicle in motion because there is more airflow through the condenser. Cycling can either mean the system is undercharged, or if the system is fully charged you can have a bad cycling switch (at the accumulator/drier).

Customer: replied 3 years ago.

Ok. cycling switch was replaced so i would go with an undercharge. Another thing that the underhood decal is not readable anymore. Could you tell me how much freon i need to charge on this system?


The system holds 1.6 lbs of refrigerant. If you are charging with 12 oz cans, that would be 2.13 cans of refrigerant.

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