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Where Is The A/C Compressor Relay Located? | Complete Guide
Qirun Auto Parts
Where Is The A/C Compressor Relay Located?
Complete Guide to Finding, Testing, and Replacing Your Car’s AC Compressor Relay
Understanding Your Vehicle’s A/C Compressor Relay
Whether you plan on doing vehicle maintenance yourself or relying on the competence of a certified automotive technician, it’s good to know at least a little bit about your vehicle’s AC system. The compressor relay is a critical component that controls power to your AC compressor, and knowing its location and function can save you time and money.
“The AC compressor relay acts as an electrical switch that controls power to your AC compressor. A faulty relay can mimic more expensive compressor problems, so knowing how to identify and test it is essential for proper diagnosis.”
Where Is the A/C Compressor Relay Located?
Primary Location: Under-Hood Fuse Box
While all vehicles are created slightly differently, for the most part, the locations of air conditioning system compressor parts are as follows:
- In the under-hood fuse box, you will typically find air conditioning relays
- This box is usually located near the battery or along the fender wells
- Most fuse boxes have a diagram on the underside of the cover indicating relay positions
Secondary Locations to Check
- Interior fuse panel – Some vehicles place relays inside the cabin, typically under the dashboard or on the driver’s side kick panel
- Near the compressor itself – Some European models place the relay close to the compressor
- Separate relay box – Some trucks and SUVs have additional relay boxes in the wheel well or behind the headlights
Did You Know?
Approximately 30% of AC compressor “failures” are actually just faulty relays that can be replaced for a fraction of the cost of compressor replacement.
What Is an A/C Compressor and How Does the Relay Work?
The A/C Compressor
So that your vehicle’s air conditioning system performs at the highest level, you must have a fully functioning compressor. Acting as your A/C’s power units, the compressor:
- Pressurizes refrigerant before pumping it to the condenser
- Circulates refrigerant throughout the AC system
- Is typically located with other belt-driven accessories at the front of the engine
The Compressor Relay
The relay is an electromagnetic switch that:
- Controls high-current power to the compressor clutch
- Is activated by a low-current signal from the AC control head
- Protects the vehicle’s electrical system from compressor power surges
- To both the clutch and the compressor for your vehicle’s A/C system, power is supplied courtesy of the relay
Signs and Symptoms of a Faulty or Failing Compressor Relay
The compressor relay involved in your vehicle’s air conditioning system may be faulty or failing if you notice the following:
1. No Cold Air
If the air conditioning system for your vehicle isn’t providing any cold air, the A/C relay may have failed. No air can be produced by the system because the compressor won’t operate – because the relay failed. While this is the most common issue if cold air isn’t being produced by automotive air conditioning systems – there are many other potential causes.
2. Non-Activation of the A/C Compressor
Again, your vehicle’s air conditioning system can’t operate if the compressor doesn’t turn on. If it doesn’t activate, it could be a problem with the relay. Listen for a clicking noise to detect whether or not the compressor has been activated. A failed relay will prevent it from getting the power it needs.
3. Cooling Is Inconsistent
The relay powers the compressor. Cold air can’t be produced correctly if the A/C system isn’t functioning properly. The compressor may be receiving intermittent or weakened power from the relay if the relay is failing. This means the A/C system will function intermittently or in a weakened manner.
4. Clicking Sounds From Relay Area
A rapidly clicking sound coming from the fuse box area when you turn on the AC often indicates a failing relay that’s attempting but failing to engage properly.
How to Test Your A/C Compressor Relay
Visual Inspection
Remove the relay and check for signs of burning, melting, corrosion, or damage to the pins and housing.
Shake Test
Gently shake the relay. If you hear rattling, internal components may be broken, indicating need for replacement.
Swap Test
Find another relay in your fuse box with the same part number (often horn or fan relays) and swap them to see if the problem moves.
Multimeter Test
Use a multimeter to test for continuity and proper resistance values according to your vehicle’s service manual specifications.
Replacing Your A/C Compressor Relay
If you’ve determined that your AC compressor relay is faulty, replacement is typically straightforward:
- Locate the fuse box and identify the AC compressor relay (consult your owner’s manual)
- Note the orientation of the relay in its socket
- Gently pull the relay straight out (you may need special removal tools for some vehicles)
- Insert the new relay in the same orientation as the old one
- Test the AC system to ensure proper operation
Important Note
Always use a replacement relay with the same specifications as the original. Using an incorrect relay can cause electrical problems or damage to your AC system.
Preventive Maintenance for Your AC System
Regular maintenance can help prevent AC compressor relay and system failures:
- Run your AC system periodically year-round to keep components lubricated
- Have your AC system inspected annually before the cooling season
- Address refrigerant leaks promptly to prevent compressor strain
- Keep the condenser clean and free of debris
- Check electrical connections for corrosion and secure fit
Conclusion: Knowledge Saves Time and Money
Knowing where your AC compressor relay is located and how to identify problems with it can save you from unnecessary repairs and expenses. While relay replacement is often a simple fix, always consult a professional if you’re unsure about diagnosis or repair procedures.
Regular maintenance and prompt attention to AC system issues will help ensure years of reliable cooling performance from your vehicle.
Professional AC Components from Qirun Auto
With 25 years of manufacturing experience, Qirun Auto provides high-quality AC components including relays, compressors, and complete system parts. Our products offer:
- Precision engineering for perfect fitment and performance
- Rigorous quality testing
- Competitive pricing
- Comprehensive warranty coverage
- Expert technical support
Contact Us for Expert Advice and Quality Parts
Address: Xianan Er Shangyuan South Industrial Zone, Guicheng Street, Nanhai District, Foshan City, Guangdong Province
Phone: +86-13690143493
Email: a13690143493@gmail.com
Websites: www.qirunauto.com | <
