A reader asks:

I have a 2013 Kia Sorento. The compressor makes a sort of grinding, growling like sound when turned on. When the proper amount of freon is in the system. It cools fine. However, about every 2 years, it requires Freon to be added. Currently, I will be replacing the compressor, condenser/accumulator, expansion valve and all O rings. Is there any additional components that need to be replaced? Like any of the AC lines to ensure there are no metal filings in the system?

There are a few different ways you can go.

Why A/C Compressors Fail, and What Can Happen When They Do

A/C compressors typically fail because of a worn bearing. Bearings will wear naturally over time, but they will wear out faster if they’re poorly lubricated, if they’re under an unusual amount of strain (say, because there’s a coolant leak), or if there are contaminants in the system. Usually, when a compressor fails, it will make some noise to tell you failure is imminent.

A/C Compressor Cross Section
A/C Compressor Cross Section, courtesy Mahle

However, sometimes A/C compressors fail in dramatic fashion. The compressor turbine will explode, sending metal shrapnel into the coolant flow. These metal bits will then deposit themselves in the condenser, expansion valve, and anywhere else there’s a good place for metal pieces to sit. If a compressor fails in this manner, most of the A/C system needs to be replaced, as there’s no reliable way to make sure all the metal pieces are removed otherwise.

When an A/C compressor fails, many shops will recommend replacing the entire system for the reason above. However, it’s not always necessary to replace the entire system.

What To Do When It’s Time To Replace An A/C Compressor

Historically, A/C compressors have been very costly to replace ($1000+). If this is the case for your vehicle, you want to replace the entire A/C system when you replace your compressor. However, for most vehicles, there’s a likely very inexpensive ($200) compressor available aftermarket.

These cheap aftermarket compressors aren’t great, but they should work OK for a few years. And because they’re so cheap, it can sometimes make sense to just replace the compressor only. The thinking is:

  • Most of the time, compressor failure doesn’t result in metal contamination in the system
  • If/when there are metal contaminants, they’re not guarantied to cause another compressor failure
  • By replacing the compressor only, you can save hundreds of dollars in parts costs and at least that much in labor

So our recommendation here would be:

  1. If a replacement compressor is very costly, OR if there’s definitely metal in the A/C system, replace the whole system
  2. If you’re doing the repair yourself and/or your shop will warranty a compressor replacement only, just do the compressor
  3. If you do the compressor only and there’s a chance of metal contamination, get a cheap one. That way, you’re not out a big investment if the new compressor fails.
  4. If you’ve already tried doing the compressor only and it’s broken after a few weeks of use, you need to do the whole system

Finally, anytime you replace any component in the A/C system, be sure to have the system flushed. This will remove contaminants that can lead to failure.

AC System Flushing Machine
Most repair shops have an A/C flushing machine like this one. Flushing the A/C system just to flush it usually a waste of money, but flushing it is required anytime you replace a component. Image courtesy Mahle.

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