Dishonest mechanic?

I was using my AC basically on a daily basis and have never had any issues with it. Then I took my car in for an unrelated issue, and when I picked it up the mechanic said “DO NOT USE YOUR AC, it will cause you car to stall. I can fix it for $675” It’s true. Now. My car does stall if I run the AC, but this was never an issue before I brought it in. My mechanic has a history of finding pricey, unrelated issues that he recommends getting fixed. Could my mechanic have caused the problem just to make business for himself? Or is it possible that my AC showed no signs of trouble until that particular day and then suddenly, boom, in the hands of a skilled mechanic who was only running the car for unrelated diagnostic purposes, it crapped out completely?

What was the unrelated issue?

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Is this an old car or a new car?

What does it idle at now?

Does it stall at idle or while driving too?

If this mechanic has a history of finding expensive repairs, why do you keep going back?


My car suddenly began making a loud sporadic rattling/vibrating noise coming from underneath. The mechanic said it was the swing arms, which is something he recommended on a previous visit. On that previous visit it was just a pre-winter once over. And there was no rattling Of any kind under my car before but, like this AC issue, he gave me the car back and warned that my swing arms were starting to fail and they would be rattling. Sure enough, there was a new constant but quiet rattle. Then a few months later the big loud rattle and the AC problem.

It stalls at idle in park and in drive, I don’t dare try it While the car is moving because it is such a sudden and lurching stall. This is only the second time I’ve been to him. I moved to a new state and gave him a try because the shop seemed friendly and whatnot. the car is old (2001) So I gave him a pass on the first problem discovery assuming he was correct because I don’t know enough about cars to know better than a professional.

I’m not there, but my read on this is that the mechanic is doing a good job at looking for future problems and letting you know in advance of possible upcoming problems. If he were trying to take advantage of you he would of pressured you heavily to replace the swing bars (whatever they are) sway bars? The AC problem is probably coincidental. It sounds like the compressor is is starting to sieze. If he was going to sabatoge for a buck he could’ve chose a hundred different easier things to do.


What leads me to be suspicious is that the symptoms of the problems he’s warning me about don’t exist until he sees the car and warns me that they exist, then those symptoms are present the very next time I start the car. There was no rattling until he said “your car has a problem that will cause it to rattle” and the AC worked just fine until he said “using your AC will stall your car”.

Did he offer a solution to the problem?

Yes. He suggested that he replace the compressor for $675.

If you are not comfortable with this mechanic you may always second guess his work. So it probably isn’t a good match. Check with people you may know or people you work with and get some recommendations on a good shop. Bring your car there and have the AC checked.

Car repair is a business transaction. Like any good business transaction, get a second opinion and several quotes.

Since your car is fuel injected, the old trick of turning down the idle would not apply, however in some models you can replicate the same issue by turning UP the idle. Once you get past the where the computer detects that your foot is off the gas, then it no longer controls the idle and engaging the AC can stall the engine.

This is why I asked what the engine is idling at. It should be around 700 RPM for most cars and it should not change when you put it in drive and/or turn on the AC, headlights, fan on high etc.

BTW: a few facts about the vehicle would help. 2001 Honda. What model? 4 cylinder or V-6? Miles?

Find another mechanic and get the DO NOT USE YOUR AC problem diagnosed. You might get a decisive insight into the problem.


You do get that feeling sometimes and I’ve been to mechanics I suspected of something shady. For that matter, I’ve also had a couple of dentists I suspected of doing unnecessary work. If you’re concerned get a second opinion.

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I think its just really crazy timing, going into a shop to get something else checked out and then are told about this other problem that wasn’t there until after being told about it. Then sure enough it was noticeable and actually happening.

I noticed there was a time I had put my car a 07 mazda 3 sport hatch, into park after getting home and the car shut off and turned back on, but the key was still in the ignition and in the on position, I did have my A/C going and it stalled and lurked forward but there was no other times it happened. I did tell my mechanic about it and there was nothing found, however I was having some bad battery issues at the time and iirc they mentioned the negative cable was not on snuggly. Although your case could just be timing like I said earlier and maybe a one time thing.

This is addressed to you doubters . . .

Do you believe a failing ac compressor can NOT cause the engine to stall cold turkey when the clutch engages . . . ?!

I’ve seen it plenty of times

I also think the mechanic is looking out for his customer by giving them a heads-up, in regards to problems which were obvious to him

What if he had seen the ac compressor was failing, knew it could cause the engine to stall, but didn’t say anything to the customer . . .

Would you blame him for NOT warning you . . . ?!

Would you think he sabotaged the car . . . ?!

It seems that a lot of people think all mechanics are lying lowdown dirty thieves, unless they can prove otherwise

Doesn’t it make life difficult if you always assume the worst of people you meet . . . ?!


My suspicion stems from the fact that the problem is now quite obvious to me when there were zero signs of it before. If I drove in to the mechanic with 4 perfectly good tires, and asked him to check the battery, and upon returning the car to me he said “by the way, you’ve got a flat tire” I would suspect that the tire had gone flat while the mechanic had the car. It’s the same situation. The AC showed no obvious signs of failure. I gave the mechanic the car. He fixed an unrelated problem, then told me the AC had failed. I got in the car to drive it home and sure enough the problem he described was glaringly obvious, when it was totally undetectable before.

My original question was whether an AC compressor could be slowly failing without showing any obvious signs of failure, and then suddenly fail. I don’t think all people or even all mechanics are dishonest. I’m simply suspicious of this person who seems to often place himself in convenient and suspicious circumstances.

Well I would certainly get an outside opinion on such a situation if it were me @db4690. Why have doubts questioning the honesty of someone you trust with your car and your cash when their honesty, or lack thereof, can be easily verified? Who was it who said “trust but verify?”

There are unscrupulous mechanics are there. Fortunately not all.

Find another mechanic and move on. You’ll waste a lot of time and money with this guy. No mechanic I know of is going to start testing random systems unless they suspect a problem.

The car is a 20 year old collection of used parts; any of which are subject to fail at any time. When it comes to aged cars everything on it wears out at the same time. However, your story is murky.

You state that you were “using my A/C basically on daily basis with never any issues”. (paraphrased)
Then you state that it “does stall if you run the A/C but this was never an issue before you brought it in”.
Which is it? A lot of wordplay going on here and that does not come across well…

You say that “my mechanic has a history of finding pricey, unrelated issues…”.
So if you feel that way why do you even have a history with him?

You have not stated what the problem with the compressor is but yes an aged compressor can go out anytime either from a failing clutch or the compressor lunching itself due to age and lack of refrigerant oil. The odds of this being sabotage are zero IMO.
The only surprise to me is that the compressor has lasted near 20 years.

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IMO Good mechanics look for suspension problems after a brake job. They check brakes during a suspension job. They check belts, hoses and lines when doing engine work etc. etc. They check everything that time alots them. Then they can inform the customer of future problems and safety issues at hand. He could tell the customer certain work can wait and certain work is urgent due to safety. He is always looking for something wrong. It’s good for the customer and business.