Car AC – How to find out what’s wrong without spending too much

Why did my car’s AC stop working?

Drawing of Toyota air conditioning parts locations

One day you’ll likely find the air conditioning in your car has stopped working. Why? Well your car’s AC is subjected to a whole lot more heat, motion, and vibration than the unit in your house. Eventually even a system without a problem will lose its refrigerant through the tiny leaks that are present in all automotive AC systems.

How much will it cost to fix the AC on my car?

Mechanic counting cash

This is a question I answer several times a day. People call and they say their car is at a shop and they want to charge $200 just to figure out what’s wrong. I say we’d start an AC quote for AC repair at $260, and then I need to do a lot of explaining. You see, our $260 is less than the other shop’s $200, but you need to understand what you’re paying for for it to make sense.

Please don’t try to service your own A/C system. In the best case, the A/C will not work as well as it should. In the worst case you can do serious damage and end up turning a small problem into a big problem. “Of course the guy making money fixing cars would say that!”, I can hear some of you thinking. I’m a skeptic as well. Here’s an explanation of the problem with DIY A/C. If you’re bound and determined to do it yourself, at least you’ll be aware of the pitfalls.

Start with diagnosis or an ac service?

Pie chart labeled, "Why the A/C doesnt the A/C work?" with 90 due to low refrigerant and 10 due to other reasons
Look! A graph! Surely the data displayed is unassailable! After all, what kind of fool would spend time making a graph of data based on un-logged anecdotal experience?

 

Most of the time, like 90% of the time, your car’s ac stopped working because it’s low on refrigerant. We could start with a diagnosis and bill an hour for our time.

“Well sir, we checked vent temperature and it was high. The blower and blend door seem to be working normally. We checked high side pressure and low side pressure and both were about 40 PSI. The compressor isn’t engaging and we suspected that the low pressure switch was the cause so we jumped it and the compressor clutch did engage, so we’re pretty sure that your system is low on charge. We’d recommend servicing the AC system. That’ll be $200 for our diagnosis and another $200 for the service. “

If we know that when a car’s air conditioning doesn’t work it’s caused by low refrigerant, why not play the odds and start with a service.

We’re not going to pretend like we don’t know what’s wrong to collect a diagnostic fee

Control panel on an A/C Recover, Recycle, Recharge machine

9 out of 10 cars need an AC recharge, what about that 1 in 10 car? Are we just wasting our customer’s money on an unneeded service? Not at all. In 20 minutes we can check a lot. Does the compressor engage? If so, how much does the AC cool. It should be able to drop the air temperature about 30 degrees Fahrenheit. Are there and oil stains indicating a leak on the condenser, hoses, or compressor? If there’s no reason not to, we then remove the refrigerant from the car and weigh it.

If we weigh it and find the proper amount of refrigerant in the system, put it back in the system and change tack. We’re only 20 minute in and still have the bulk of an hour for electrical testing or whatever.

We start with the service because it’s what you’ll most likely end up needing. We’re trying to give you a real price up front. It’s pretty likely $260 is the least it will cost to have working AC. If that’s too much, save your money, don’t waste it on diagnosis.

You may need and AC service and other AC work

Subaru air conditioning compressor

So how likely is it that you’ll get out of here for $260? Well of the 90% of cars that have air conditioning that doesn’t work, about half need nothing other than a service, so I guess your chances are around 45%. So what if you’re not one of the lucky ones? Well repair costs can range from under $100 for something small like an o-ring, to $2500 for an evaporator (the thing that gets cold; it’s buried under the dash board). There’s no way to know in advance. Even if you pay the other guys to “diagnose” the AC, there’s no way they can know either. Sorry.

What to expect when you’re expecting (working air conditioning)

So here’s the process:

  1. Service the AC system
  2. See if it works normally with refrigerant in it. If it does,
  3. Check for leaks. If the AC works and there are no leaks, it’s good news, but you’re not out of the woods yet.
  4. Come back in a week for a AC UV dye inspection. We add a dye that glows under black light. It’s great for finding smaller leaks. This check is included with the original fee and we normally recommend you drive and use the AC for about a week, then come back and we’ll check the car while you wait. If there are no leaks, you’re done. Hooray!

The process can derail at any point. We might find a big leak on the day of the service. Or it could be that the AC system doesn’t work even with the correct amount of refrigerant due to a stuck expansion valve or bad compressor. You can’t test this stuff with an empty system. And it’s also possible that you’ll drive around enjoying your newly functional air conditioning for a week, only to have us tell you you have a leak during your one week visit.

Here are some other articles you may enjoy:

Do you need to stop driving when the check engine light comes on? Find out here.

Should you pay extra for nitrogen when you buy new tires? Quick answer, NO, but you can read more here.

Do the DIY air conditioning cans work? They might, but don’t do it! Click here to find out why.

What should you do if your car won’t start? You may not need a mechanic, try these things before calling for a tow.

Are you having trouble finding a place to service your newer Toyota, Honda, or Subaru with R1234yf refrigerant? We have the equipment.

We are serious about performing proper air conditioning repairs. That’s why we became certified through MACS (Mobile Air Conditioning Society Worldwide) and use only high quality modern equipment when servicing your car air conditioning system.

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