#air conditioning
10 posts in Car Diagnostics blog about "air conditioning" — OBD-II diagnostics, DTC codes, repair. ← All posts
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Hissing from the vents: blend door, refrigerant or a blocked drain
Some hissing from the dashboard is normal air conditioning behaviour. Some is a leak. The timing and the accompanying smell separate them.
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P0530 to P0533: A/C refrigerant pressure sensor circuit
Air conditioning that refuses to engage on a hot day is usually not a broken compressor. It is a pressure reading the system does not trust.
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P0645 and P0646: A/C clutch relay control circuit
The compressor clutch is switched by a relay like any other high-current load. When the circuit faults, the air conditioning stops — and so does a lot of guesswork about refrigerant.
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Air conditioning: how to use it so it cools better and lasts longer
A few habits give more cooling and longer life at no cost. Recirculation, modes, and running it in winter.
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The cabin filter: the cheapest part, replaced least often
A blocked cabin filter is not only about smell. It cuts airflow, hurts the air conditioning, and mists the windows. Types and intervals.
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The new refrigerant R1234yf: why air conditioning service doubled in price
Cars built after roughly 2017 use a different refrigerant, and it costs several times more. Why it cannot be mixed with the old type, how to identify yours, and what it means for your wallet.
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Air conditioning smell: where it comes from and why the spray can does not fix it
That musty smell when the fan starts is biofilm on the evaporator. Why it grows there, why aerosols buy you two weeks, and one free habit that solves it permanently.
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Summer heat: why cars overheat in traffic specifically, and what to do beforehand
Cooling systems are designed with margin, but that margin is eaten away over years: a clogged radiator, old coolant, a fan that engages late. What to check in May so you are not on the hard shoulder in July.
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Variable displacement AC compressor: why "new refrigerant" doesn't help, and how OBD sees a sick pump
Fixed vs variable displacement AC compressor, how to diagnose the control valve, code B1247, symptoms, and why "clutch not engaging" isn't always an electric fault.
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AC not cooling: OBD-II diagnostics, refrigerant pressure, compressor and sensors
What OBD-II shows about the AC system: codes B1234, B10DA, high/low-side pressure, evaporator temperature, why "just add refrigerant" isn't always the answer, and how to diagnose the compressor clutch.