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AC blowing warm air. Compressor and condenser fan cycles on and off.


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Godfather17
Novice

Jun 25, 2016, 6:14 PM

Post #1 of 8 (571 views)
AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

I was driving my 2008 Mazda 6i 2.3 L, home from work today when I noticed that the AC was not blowing cold air. When I got home, I looked under the hood and noticed that the ac compressor and condenser fan were cycling on and off every few seconds. My first thought was that the refrigerant was low. However, after about one hour, I went to check out the issue again, now that I was not stressed from work. Of course, the AC started blowing cold air again. The air that it was blowing was 49.8˚ F, so my thought of the refrigerant being low was probably wrong. The AC compressor and condenser fan were both working normally again. This is not the first time that this issue has happened in the past few months. Does anyone know what could be causing this issue? The last time it was the same thing, the compressor and condenser fan cycles on and off very quickly. Any help would be appreciated. Thank you in advance for all the help guys/girls.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 26, 2016, 2:51 AM

Post #2 of 8 (555 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

Don't add refrigerant!
It just may (you have to say real temps and did for I think a vent temp) too hot where you parked during daytime hours baking in heat much hotter than it could handle defaulting to shutting down.


Rule some things out: Dirt/bugs or other debris blocking the condenser and in between condenser and radiator. If airflow is restricted pressures would go over the limit and normally shut down and cycle like you saw. Later could be cooler and behave normally so check would show things were ok so suggest looking for easy stuff first.


There isn't a lot of routine service to vehicle A/C except knowing it's clean, belt it good and tight enough, replaced on schedule.


Curious: Just how (I do all the time) know the vent temp of 49.8F) which suggests you weren't guessing? Depending on the heat load and your settings that is quite normal for certain temps so CAN work properly - important info,


T



Hammer Time
Ultimate Carjunky / Moderator
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Jun 26, 2016, 4:47 AM

Post #3 of 8 (551 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

In order to have any idea what was going on you need to have pressure readings when this problem is occurring {both high and low). It's possible you had a bad switch or temp sensor in the evaporator causing that.
It's also possible it was way over pressure for some reason and it was high pressure cycling. Seeing the pressures at that point will tell you which direction it was going.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Godfather17
Novice

Jun 26, 2016, 8:34 AM

Post #4 of 8 (547 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

The outside temperature was not too bad. It was around 85 degrees. When I first started driving the car from work, the ac was working normally. I noticed the issue when I was driving in the highway. I forgot to mention, I also checked the condenser and it was clean, no bugs or rocks. Lastly, I used a cooking thermometer to get the vent temperature.


Hammer Time
Ultimate Carjunky / Moderator
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Jun 26, 2016, 8:56 AM

Post #5 of 8 (543 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

As I already advised, you need to know what pressures are doing at the moment it goes off.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jun 26, 2016, 8:57 AM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 26, 2016, 9:00 AM

Post #6 of 8 (541 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

Still need to know what the high and low side pressure readings are when the problem is occurring to give direction as HT stated. Don't add any refrigerant until you can see what is causing what.

If you don't have the equipment or know how, have your local automotive ac tech have a look. Today's systems hold a lot less refrigerant and are not as tolerant in variances in charge weight.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 26, 2016, 9:22 AM

Post #7 of 8 (537 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

Ask if gauges are rentable. They would show what I suspected up top. If high pressure is too high it could cycle for lack of proper heat transfer at the condenser - any reason. I chose bugs or debris. That can hide in between condenser and radiator you can't tell without looking if it takes removing a cover.


An almost universal answer is going to be seek professional help. The equipment and know how plain isn't practical cost wise nor understanding for most DIYers.


BTW - as A/C goes 85F isn't anywhere near an extreme for excuses. Those 115F deals on the news forget the whole thing as too dang hot for many vehicles - A/C totally stressed out and personally too hot for me to be working on or checking things over a hot engine - plain unsafe working in that,


T



Godfather17
Novice

Jun 26, 2016, 10:43 AM

Post #8 of 8 (534 views)
Re: AC blowing warm air. Compressor and condenser fan cycles on and off. Sign In

Thanks for the advice guys. I'm going to bring it to a shop if it happens again. If it does, I'll post back what the reason was for the issue so it can help anyone else in the future.






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