Q: My ac clutch is not engaging, but there is no relay in the fuse box for the ac compressor

asked by on

I got my cars ac system looked at, and they said my compressor is not engaging and I need a new one. Well I understand that but what I don't understand is there is no relay in the ac compresser location in the engine fuse box... is this my problem? Can I use another relay to test this?

If a mechanic told you only that the compressor is not "engaging" that is essentially a useless diagnostic because it is too cryptic and too vague. The compressor in the system will only operate if the compressor clutch is engaged. That clutch is electrically controlled. So, if the circuit controlling the clutch includes a relay but the relay is missing, you should replace the relay. Be sure to use the right relay with the correct electrical rating. If you are unsure if a relay is in the the circuit, you can determine what is supposed to be in the circuit by consulting the Factory Service Manual wiring diagram.


With regard to this vague diagnostic, "compressor not engaging", if the fault is the clutch simple causes for clutch failure have to be evaluated, so, in addition to a missing relay, you could have a broken wire to the clutch or maybe the clutch is bad. The clutch can often be replaced without replacing the compressor and indeed without even discharging the system (a huge plus). To get your a/c fixed at the LEAST possible cost, what you need is an intelligent, authoritative and conclusive diagnostic stating EXACTLY what is wrong and why. If you request an a/c system diagnostic YourMechanic will dispatch a certified mechanic to your location and get the system properly diagnosed and once diagnosed the mechanic will explain any required repairs. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My ac clutch is not engaging, but there is no relay in the fuse box for the ac compressor

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: When the car is running it doesn't want to shift gears. But when it's off it will shift gears 2004 Hyundai Accent

Hi - check your clutch hydraulic fluid level. The clutch reservoir may be one and the same as for the brake system - they both use brake fluid. I believe that most likely your clutch slave cylinder has failed and...

Q: Electrical system issues

You may be having wiring harness issues that would have to be isolated and traced for each problem you are having. The door locks could be a wiring or a lock actuator issue. These are probably random unrelated issues that...

Q: Fuel pump running with car off

Hello. A fuel pump that stays on when the ignition is turned off can be caused by a few things. If you do not believe that the behavior is normal, then it may be possible that the the ignition switch...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...