OBD Guide
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P0645

A/C Clutch Relay Control Circuit

P0645 is an OBD-II diagnostic trouble code meaning: A/C Clutch Relay Control Circuit. Common causes: a/c compressor clutch relay malfunction, open or short circuit in the relay control circuit. Estimated repair cost: $3–556.

Severity
✅ Low
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$3–556 (est.)

Symptoms

  • Check Engine light comes on
  • The air conditioner does not turn on or operates intermittently
  • Air conditioner button does not respond
  • Warm air comes out of the air ducts when the air conditioner is turned on
  • Extraneous noise when trying to turn on the air conditioner

Causes

  • A/C compressor clutch relay malfunction
  • Open or short circuit in the relay control circuit
  • Blown air conditioning fuse
  • Malfunction of the compressor clutch (coil, bearing)
  • ECU malfunction (rare)

How to Fix

  1. Check the A/C fuse and relay
  2. Replace the relay with a known good one and check the operation of the air conditioner
  3. Check the voltage at the relay control terminal with the air conditioner on
  4. Check the voltage at the compressor clutch coil
  5. Inspect the wiring and connectors of the relay and compressor clutch
  6. If the clutch is faulty, replace the clutch or compressor assembly

Related codes

P0646P0647P0530P0532P0533

Error P0645 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0645 code mean?

P0645 is an OBD-II diagnostic trouble code that indicates: A/C Clutch Relay Control Circuit

What causes a P0645 error code?

The most common causes of P0645 include: A/C compressor clutch relay malfunction; Open or short circuit in the relay control circuit; Blown air conditioning fuse; Malfunction of the compressor clutch (coil, bearing).

How do I fix a P0645 diagnostic trouble code?

To fix P0645: Check the A/C fuse and relay. Replace the relay with a known good one and check the operation of the air conditioner. Check the voltage at the relay control terminal with the air conditioner on. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0645?

Yes, but get it checked soon

How much does it cost to fix P0645?

The estimated repair cost for P0645 is $3–556. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat