Code
P1674
DAEWOO
P — Powertrain
A/c fan relay
Views:
UK: 2
EN: 8
RU: 7
AI status
Completed
Completed
100%
Causes
- Blown fuse for fan/relay circuit
- Failed A/C fan relay (stuck or open)
- Open, shorted or corroded wiring/connectors to relay or fan
- Bad ground at relay or fan
- Faulty fan motor
- Faulty PCM/ECM output driver
Symptoms
- Condenser/AC cooling fan does not run with AC on
- Reduced A/C performance (warmer than normal cabin air)
- Engine temperature rise or overheating in slow traffic
- Cooling fan runs only on high speed or intermittently
- Check Engine Light or A/C-related warning illuminated
What to check
- Retrieve freeze-frame and readiness data with a scan tool; confirm DTC and freeze conditions
- Visual inspection: relay, fuse, wiring, connectors for corrosion, heat damage or loose pins
- Check fuse(s) for fan/relay circuit continuity and correct rating
- Verify relay operation by swapping with a known-good identical relay if available
- With AC requested, check for battery voltage at the relay supply terminal
- Check for control signal at relay coil (from PCM) when A/C is turned on
Signal parameters
- Relay supply (pin B+) with key on: approx. 11–14 V (battery voltage)
- Relay coil/control signal: switching between ~0 V and battery voltage or PCM-driven low-side (varies by model) when A/C is requested
- Closed relay contact resistance: near 0 Ω (very low, typically
- Fan motor current draw (typical range): roughly 5–30 A depending on fan design — significantly higher indicates motor or fan shroud issue
- Open-circuit on control circuit: infinite Ω; short to ground or battery: near 0 Ω
Diagnostic algorithm
- Read and record freeze-frame data and all stored/related codes; clear code and attempt to reproduce
- Perform visual inspection of relay, fuse, wiring harness, and connectors for damage or corrosion
- Verify presence of battery voltage at the relay supply terminal with key on; replace blown fuse if found
- With A/C requested, probe relay control coil terminal and observe switching; use a test light or multimeter to confirm coil activation
- If relay does not energize but control signal from PCM is present, replace relay and retest
- If relay energizes but fan does not run, apply 12 V directly to fan motor to verify motor operation; replace motor if it fails
- If fan runs when directly powered but not when relay is energized, check relay contacts and supply/ground circuit for continuity and repair wiring/connector issues
- If wiring and relay are good but no control signal from PCM, test PCM output circuits and grounds; consult manufacturer wiring diagrams before replacing PCM
- After repairs, clear codes, run vehicle to normal operating conditions and verify fan operation and that code does not return
Likely causes
- Failed A/C fan relay
- Blown fuse or poor fuse connection
- Open/short in relay control or supply wiring
- Corroded or loose relay socket/connector ground
- Defective fan motor drawing excessive current
Fault status
Status
A/C fan relay circuit malfunction detected — relay control or supply circuit fault; condenser fan may not operate properly.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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