A/C air temperature fluctuating

Tiny
TERESLUTHER
  • MEMBER
  • 2018 FORD EXPLORER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 45,000 MILES
My A/C stopped being cool enough, so I took it for a tune up. Garage said the compressor was bad and replaced it. I noticed right away the air temps were cycling from cold to warm every few minutes. Seems more obvious when the car is sitting, but not in park. Garage says, that’s impossible and to prove it parked it running for a long time. I insisted they drive it. They said it’s not noticeable. I insisted. Grudgingly they charged the system. The problem is still there. I have a video of it cycling from 69 to 80 while I’m driving. What can it be?
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Wednesday, June 8th, 2022 AT 1:27 PM

5 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Great job with the video. Clearly that is an issue so not only should it not range up and down as much, but it should be colder depending on the temp outside. No matter what, I would expect it to blow at least in the 60s.

So, let's start where we always have to start and that is with the pressure when the compressor is cycling.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

If they charged the system, then they may have overcharged it at this point, but I suspect the issue is there is a restriction in the system and the pressure will tell us this.

We want to hook the gauges up and see what the static pressure is.

Then start the engine and turn it on Max cold and tell me what the pressure is when the compressor is on and off.

If you want to just get a video of the gauges, then that is fine. Once we know what the pressure is we will have a better idea what the issue is.

Here is a chart that talks about possible causes as well. If you don't have a gauge set, then most all parts stores rent them.

I am sure we can check the pressure using this info and then if you want to take it back, you can armed with info.

You can even ask them if they checked them and what they are to see if they are telling the truth.

Let me know if you have questions. Thanks
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Thursday, June 9th, 2022 AT 11:46 AM
Tiny
TERESLUTHER
  • MEMBER
  • 4 POSTS
I have no idea how to do that test. Is this something they do at Auto Zone?

This problem started right after they replaced the compressor, but before they charged it. Honestly, I am not even sure they charged the system, it felt like a bone they threw at me because they claimed what I experienced was impossible and they wanted me to take the car and leave.

I’m leaving for Florida in a few days. I have a very reputable dealership down there that has been helpful and unlike this garage, listens to what I say. I was hoping for confirmation that I’m not crazy and you gave it.
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Thursday, June 9th, 2022 AT 12:04 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. No problem if you aren't going to run the test but they would have the tools at AutoZone, but they would not do it for you.

What I would do is take it to this other dealer because if this all started after the compressor, either the new compressor is faulty or the old compressor failed and released metal into the system, and it clogged the system.

However, the dealer should check the pressures first thing and I would be interested to know what they are. Even though they may not need my help it would still be nice to confirm what I am thinking and what they are seeing.

Thanks for the update.
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Thursday, June 9th, 2022 AT 1:43 PM
Tiny
TERESLUTHER
  • MEMBER
  • 4 POSTS
Hi, I to let you know the outcome of my issue. My dealer tried re-programming the HVAC. Didn’t resolve it. They discovered a known Ford issue that the blower motor was shutting down from a short in the system. The entire system had to be rewired. Good as new and I only paid for the re-program.
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Saturday, July 2nd, 2022 AT 10:17 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,125 POSTS
Hi,

Thank you for the update. We're glad to know its fixed.

Please feel free to come back anytime in the future. You are always welcome.

Take care,

Joe
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Monday, July 4th, 2022 AT 8:52 PM

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