By far the most common reason for the compressor to remain disengaged is because of low system pressure, but other things could also cause this. The clutch is usually an electromagnetic design, and it sometimes fails. The wiring in between these components could be loose or damage. Or, the limit switch could have malfunctioned.
If the compressor is not engaging due to low system pressure, don't automatically assume that buying a can of refrigerant will solve the problem. Air conditioning systems are designed to be air tight, and if refrigerant leaked out, there's a reason. While some leaks are slow and may take weeks or months to drop below the limit switch threshold, some leaks can be very rapid so that the system won't work no matter how many bottles you try to use.
Diagnostic kits are available at just about any auto parts store that allow you to determine the location of leaks yourself. The kit includes a can of refrigerant mixed with a tracer dye that is highly visible under infrared light, also included with the kit. To use the kit, you inject the refrigerant into the system, and then use the infrared light to locate the source of the leak. With any luck, if there's a leak, you'll see what component it's coming from.
Note that in some cases, failure of the service port (where you charge the system) can result in the valve being stuck closed, showing a high system pressure on the gauge even though the system is essentially empty. Any time you see abnormally high pressure on the gauge, you should investigate this, since it normally takes a LOT of refrigerant to get it to that point. I recently came across a case where the valve was stuck shut, no refrigerant was getting charged into the system, but applying the charging bottle and gauge indicated the system was overcharged (even though it was not).
Testing for a failed clutch can be conducted by verifying the electrical signal to its connector. If the system is properly charged and the air conditioning is set to turn on, you should see the signal applied. If it appear, but the clutch doesn't respond, it may have failed. Often, the clutch and compressor are only sold as a single unit and unfortunately, it can be very expensive. If you don't see the signal at the clutch telling it to engage (and the system is at the proper pressure), it means that the problem is upstream of the compressor--either the limit switch has failed, or the wiring has an issue.
Unfortunately, while you can certainly go a long way to troubleshoot and properly identify the problem yourself, in many cases you'll have to open the system up to the atmosphere. This will generally require someone to evacuate and recharge it for you, and this can be quite an expense, even if you do the majority of the repair work yourself.
The fans going on does NOT mean the compressor is running. LOOK at the compressor to see if it's running. If it's overcharged, the high pressure switch will prevent the compressor from running
The compressor has a high limit switch which keeps the compressor from cycling when the pressure is too high! It could be the cycling switch, a relay, the a/c control head itself! I would let a trusted qualified technician troubleshoot it before the high pressure causes an injury or major failure in the system! Hope this helps!
Your compressor won't engage.
it was working fine around 3 days ago. when i turn the ac on, the fans kick on meaning the compressor is working.
defogger wont defog the windows.
i tried recharging using artic freeze r134a but the PSI reading is above what it should be.
any suggestions?
2004 civic
