Air Conditioning Auto Repairs

automotive-air-conditioning-mechanic

Sometimes air conditioning auto repairs are not as complicated as they may first seem. Let me give you a quick example of what I’m talking about.

A customer recently visited me for a car air conditioning repair. He informed me that the air conditioning stopped working towards the end of the warm weather in 2008.

He thought for sure that this would be an expensive problem and decided to hold off on the diagnosis and repair of the air conditioning system until the warm weather returned. This is probably what most automobile owners would do in this situation.

Automotive air conditioning diagnosis

automobile-air-conditioning-diagramMy first step in any auto repair troubleshooting is to perform a visual inspection. But I let myself down and did not perform this step. In my mind I thought that the Freon had leaked out, and that’s why the compressor was not coming on. This is the most common situation when it comes to automotive air conditioning not blowing cold air.

I connected my manifold Gauges to the air-conditioning system. I found that not only were the pressures the same on both sides as they should be with the compressor off, but the vehicle currently had a full charge of Freon. My customer was buzzing around me trying to figure out why I had a surprised look on my face.

I said to him, I have good news and bad news. The good news is your air-conditioning system is filled with Freon and ready to blow cold air. The bad news is the compressor is not coming on and it is apparently an electrical problem.

My customer said oh my god, not an electrical problem. I said calm down and let me start poking at it and see what I find. I checked the air-conditioning fuse and it was good. So I returned to my normal diagnostic procedure. I performed a visual inspection of the electrical wiring and connectors to the cars a/c system.

Air conditioning auto repairs

A/C Compressor

A/C Compressor

I had the key on engine off and decided to check for power at the A/C compressor. When I grabbed the electrical connector, which was a two wire simple power and ground connection, the compressor clicked on and engaged. So the problem turned out to be a poor connection to the air-conditioning compressor. No actual parts and a very small amount of labor repaired the A/C system.

But that is not the end of the story. The reason for the poor connection was that the connector was actually damaged. The plastic housing that holds the terminals had a crack in it and allowed the terminals to back out. I question my customer about how strange this was that there was damage to this connector.

My customer said, oh I forgot to tell you. Last year my belt broke and I had it replaced while I was out of town at a local gas station. So actually what happened was when the belt let loose it damaged the air-conditioning compressor electrical connector.

But yet another lesson to be learned about air-conditioning auto repairs. It is not always a good idea to put off diagnosing and repairing this system even if you will not be using it for months. My customer knew that his air was not working and suffered with his dark secret all winter long.

He actually told me that he was dreading that summer was approaching, because he knew the A/C repair would be necessary. So why spend five or six months worrying about something that may be repaired very easily. Also if the situation was different and there was a major A/C leak and the system was left empty for that long, further damage may have occurred and increased his auto repair costs.

This story is one reason that I decided to post a DIY auto air-conditioning repairs section to my new car repair website. You will find many pages that will not only explain the theory of operation, but also discusses common automotive air conditioning problems.

About Mark
Mark Gittelman is an ASE Certified Automotive Master Technician With more than 26 years experience in the auto repair field. See Mark's Car Repair Credentials and Work History on Google+.

Comments

57 Responses to “Air Conditioning Auto Repairs”
  1. nick says:

    Hi Mark I got a 2003 Nissan Maxima with 50k miles. The a/c blows cool but not super cold like it used to. The pressures are 80 on the high side and 90 on the low side. I tapped on the expansion valve thinking it was possibly stuck but nothing changed. Bad compressor? what do you think?

  2. Deb says:

    We just had a new compressor and dryer replaced in a 04 Chrysler Pacifica.
    The air is cold but not as cold as it used to be with the old unit. The air feels the same no matter what setting its on. It has full range of temps.
    We are confused because it’s all brand new parts. Any ideas?
    Thank you ;)

  3. Markos says:

    Dear Mark,

    I am driving one of the first Lexus models (1990) and the A/C is blowing super-cold, even at the midway level (between hot/cold) when it has freon. But it runs out in two to three days. I have no idea about cars and I’m kind of broke. Please give me advice (perhaps it may be fuse, connection?)…hopefully not a big leak!

    Thank you,

    Markos

  4. Andrew Vilailack says:

    Mark: Thank you for your service and quick response. This means alots to me and others blogger.

  5. Mark says:

    Andrew: The AC systems on a Mercedes can be very complicated. It might be best to have a dealer run a diagnostic test to confirm the problem. The list of possible causes is huge and I would not want to start guessing from the info you provided.

  6. Andrew Vilailack says:

    Mark,
    I own a 2000 Mercedes ML 430 SUV and the AC works intermittently. The AC will blow cold air at low to med high speed setting but not at high setting. If I drive drive the vehicle with AC running and turn on the AC later, the system will not blow cold air. When the AC is working the temperature of the blown air is 48 to 68 degree. I have to charge the freon once a year. Please help, I am confused.

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