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Discussion Starter · #1 ·
Hi all.Just bought a brand new 2017 V6 Mustang.

Noticed the air conditioner compressor keeps cycling on and off about every 10 seconds with the air conditioner on(coolest temperature setting,recirculation button on,fan at low setting).Can even see the compressor clutch go on and off when I looked at it with the hood open.Air blowing through the vents seems cold at all times.But noticed that when I turn the fan speed to the highest setting the compressor stays on and does not cycle on/off. Is this cycling normal? Is this some kind of energy/fuel saving feature? Don't remember this happening on other cars I have owned in the past(including my previous 2014 Mustang).Thanks for any info.
 

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I just charged my AC system from zero and went through something similar. A compressor cycling every 10 seconds could mean the system is low on refrigerant. I would get a reading on the high & low pressure ports and see what you're getting. Mine is set up at 35psi low and 200psi high and this yields 44 degrees at the vents.
 

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Discussion Starter · #4 ·
I have heard both sides of this.Some say the 10 second cycling is normal,Some say no. Will make an appointment to have it checked out.
 

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I’ve noticed my 2017 v6 does that to with cycling all the time. I’m not worried about it because the a/c freezes me out. If it’s not broke don’t fix it.


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Discussion Starter · #6 ·
Hey "JustinM73" thanks! Mine cycles compressor on for about 5 seconds then off for about 8 seconds both at idle and highway speed.With it set at coldest temperature setting and at lower fan speed.85 degrees outside today.Sound about the same for you?And yes mine cools the interior pretty good it seems.Just seems weird to cycle that often.
 

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One thing I have noticed with 2017 mustang is they are way more advanced than the s197. But my a/c will freeze you out no matter how hot it is. I live in Texas and already had 100 degree days and the a/c works really well in hot weather. Only complaint I have with car is the driveshaft pops when putting in gear on cold start I’m taking it to ford dealer next week.


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Check your cabin filters. A clogged filter can cause the low side pressure to drop low pressure enough fast enough to cause short cycling due to not enough air volume passing through the evaporator coil and trip the low pressure cut off switch. Believe the switch will open the circuit when the pressure drops to >20psi.
 

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Discussion Starter · #10 ·
Got the car back from the dealer today.They said the cycling is not normal.But agreed that the cabin is still cooling down though.But not good enough they said.Said they could not find where a leak was (I am assuming there was a leak?).So they are saying it must be coming from the evaporator which is hidden behind the dash.They are telling me the whole dash has to come out and that it is a huge job and they will need the car for like 3 days to do it.Said they had to order parts and to bring the car back when parts come in.Said that after researching whatever they research that this has happened on other cars.Hmmm??

Don't like the idea of them tearing my whole car apart because I know it will lead to other issues from some screw up.Or the issue will still be there after they change the part.So I my bring it to another dealer just to see what they say.Would not care so much if this was some old car but it is brand new and hate the idea of tearing it apart.I bought a new car to avoid this kind of crap.But guess not.

I came home and checked the cycling again with the car idling in my driveway.Checked it on all 7 fan settings.First 4 fan settings it cycled about every 5 seconds (but still cooled car).3 highest fan settings did not cycle(and cooled car).It was about 85 degrees out.

So I may just leave it as is for awhile and see what happens.Maybe have my other dealer check it at my next oil change.I will see how it is in the hot summer months coming up.
 

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Discussion Starter · #11 ·
Got a call from my dealer today saying the new evaporator was in and he wanted me to make an appointment.I told him I am going to hold off because the air conditioner has been keeping the car nice and cool in the 90 degree weather we have had recently.And told him I don't feel like having my brand new cars interior totally pulled apart.Yes the compressor is still cycling every 5 seconds but it does it less at higher fan speeds.So since it is still under warrenty I am just going to let it be for now and see what happens.Knowing me I will eventually want another car anyway in the next few years so...
 

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The compressor will cycle less on high fan/blower settings because its moving more warm air over the evap coil which keeps the low pressure switch from tripping. The only way to truly know if there is a leak is for them to draw down the refrigerant from the system and put a full vacuum on it for at least an hour (checking that it doesn't lose any vacuum) and also measure the weight of the removed refrigerant. There is a sticker under your hood that tells you how much refrigerant in weight units it takes to fill the system. All AC systems leak a bit over time especially at the compressor because of the moving parts leaking at their seals. That being said, IF your system is truly low on refrigerant it can eventually lead to premature failure of the compressor and since you have been put on notice by a dealer you may be giving Ford grounds to deny any future warranty claim. Just my 2 cents.



 

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Discussion Starter · #13 ·
Well now after a hot and humid summer the air conditioner kept the car nice and cool.Yes the compressor still cycles but as long as the car is kept cool I am not letting the dealer tear the interior out.Will see what the future holds.
 
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