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A/C problem eludes diagnosis and fix

This is a classic problem of ?It won?t do it for the mechanic?, and it?s driving us crazy!

My wife has a 2001 Dodge Stratus 4dr SE. A little over a year ago the A/C started having this problem where it will stop blowing cold air and replace it with warm or hot air. The problem started a little while after we took it to the dealer for some unrelated work, so we took it back, but they said it worked perfectly all day for them, so they couldn?t do anything. It worked for a few weeks after that, then started up again.

So we took it to another mechanic (highly rated), but the result was the same: it worked fine for them.

It worked for us for a weeks or so, and by time it started up again the weather was cooling off so we just let it go.

This summer, it seemed fine for awhile, and then started having the same problem. We took it back to the same shop for its 100k maintenance and had them look at the A/C again. Of course it worked great for them, and they couldn?t find any problems.

Here are the details:

- It sits in our driveway each evening until my wife takes it to work at 8am

- It works fine each morning when she drives it to work

- It sits in her work parking lot all day in the sun

- On the way home in the early evening, it may work for 5-10 minutes, or it may not work at all

- If she switches it to the ?Defrost? setting where the air only comes out of the top vent, it always blows cold air. But it isn?t powerful enough to really cool off the interior.

- If she switches it back and forth from defrost to the front/floor vents, it sometimes blows cold for another few minutes before going hot again

- The day I made the appointment last week, it started working perfectly for her, and did so for four days, including the day I drove it to the dealer in the morning until I got it home at 4pm. The dealer said they checked everything, drove it around, ran it in the morning and in the afternoon, and it worked great

- Sunday, the day after the appointment, she drove it to a friend?s house and it worked for 5 minutes and then stopped. This was at 11:00 am.

- Every now and then, only when the A/C is running, the car will make a brief noise that sounds like a goose that swallowed a fog horn. It only lasts for a few seconds max. The dealer heard it and said it seemed to be coming from the passenger side, near the firewall, but he couldn?t isolate it further. It never did it in the shop, only when he was out driving it. It?s loud enough for a car next to you at the stoplight to hear, if their windows are down.

- The noise doesn?t seem to have any bearing on whether the A/C is blowing cold or not.

So after spending a couple hundred dollars to have mechanics tell us it?s fine, we are super frustrated. Most of the time it happens it?s too late for a shop to look at it. And if we dropped it off somewhere after it stopped working, it would most likely be fine in the morning, since it usually is for us.

What do we do?

I guess if I had some type of financial interest in your problem I would read your post but I don’t, your post is too long for me.

Well, the tome is a bit long to read but based on skimming the symptoms and making a wild stab in the dark I’d say there is an erratic problem with the blend door.

I’m not familiar with the blend door setup on this model car but if it uses a stepper motor the noise could be related to that.
A blend door is what shuts the airflow through the heater core off. Depending on the door position the vent air may be cold, hot, or in between. Blend door problems are not that rare on any make of car.

Decided to take a quick look and here she is.

Sounds like moisture in the AC refrigerant. Cold air until moisture freezes blocking internal AC orifice, then warm air until ice melts. Get the system vacuumed and recharged with new refrigerant.

This is what the mechanics have said, but when they look at it, they can’t find any problem. And I can’t tell if they are just saying that because it blows cold air while they test it or if they are really running some sort of diagnostic on the system. Should I just gave the blend stepper motor replaced? How hard is this and could a competent amateur mechanic (brother-in-law) do it.

This was done when we took it in a year ago. The problem went away for about a week and then came back. Also, it works for the 45 minute drive to work each morning.