DIY AC freon for car or professional fill up

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misterno
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DIY AC freon for car or professional fill up

Post by misterno » Tue May 15, 2018 3:31 pm

My car is 2009 Toyota Yaris and lately AC has been blowing warm air or not enough cold air. The volume is good but it is not cold enough

I took my car 2 different shops, one said the valve behind the dashboard is stuck and my freon is full to the top so no charge needed. This did not make sense because the air volume is good

Second place said there is no leakage and freon level is low and they need to fill up freon. So I asked about the AC kits they sell in walmart for 20-30 bucks. They said, those only work for one season then it will blow warm air again. They also said, the AC system has to be completely emptied and make sure there is no moisture or anything in the tank and then fill up freon. This will enable cold air blow for many years

A friend told me, these shops place the gauge only for a minute and that is why gauge is not showing no leak but if the gauge was placed for a longer time,it will show a leak.

Would you recommend DIY like buy the can from walmart or take it to a shop and they will definitely say there is a leak let's fix it for 400 bucks and then other 200 for freon?

Car is 9 years old and never needed a freon charge. So just because freon is low, can we say there is a leak that needs to be fixed?

barnaclebob
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Re: DIY AC freon for car or professional fill up

Post by barnaclebob » Tue May 15, 2018 3:35 pm

First find a black light and look around for dye on the hose connections, compressor, condensor, etc.

To do an AC recharge yourself correctly you should use a vacuum pump, manifold/gages, and pure or dyed R-134a (unless your car takes something else), not the fix a leak cans. The tools were available for free to rent from my autozone, yours may be different. If your system is empty or nearly empty then there wont be much environmental damage from just pulling a vacuum and recharging. There are several youtube videos online about it, see if its something you can do. I didn't think it was that hard. Here is the video I used: https://www.youtube.com/watch?v=Pdq8JAlct6s&t=419s

In my case the system (2001 vehicle, never any service to the ac system) held a vacuum for an hour so i charged it with dyed R-134a. But after this past winter I could now see the UV dye on one of the hoses so it must have been a very very slow leak. I still have adequate AC so far this year.

Don't use a fix a leak can because if you go for service after that they may not want to work on it or might charge you a lot more because your refrigerant will be contaminated. When I was calling around one place said they first test the refrigerant to make sure nobody has used a leak stop can and then gave prices for what they do assuming the fluid is clean. I didn't ask about what if it wasn't.

I'm not sure how a shop can say the Freon "is full to the top" since there is no visible gage on most systems as far as I know. Also there shouldn't be any "valve behind the dash board" unless it is some kind of air mix door which would be a problem with the climate control system and not the AC system. If your air mixture box/valve/door is malfunctioning then it could still be possible to get full flow at a high temp.

RetiredAL
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Re: DIY AC freon for car or professional fill up

Post by RetiredAL » Tue May 15, 2018 6:11 pm

barnaclebob wrote:
Tue May 15, 2018 3:35 pm
First find a black light and look around for dye on the hose connections, compressor, condensor, etc.

I'm not sure how a shop can say the Freon "is full to the top" since there is no visible gage on most systems as far as I know. Also there shouldn't be any "valve behind the dash board" unless it is some kind of air mix door which would be a problem with the climate control system and not the AC system. If your air mixture box/valve/door is malfunctioning then it could still be possible to get full flow at a high temp.
Most every car AC system has an expansion valve, those that don't will have an expansion orifice. These are typically inside your heater/AC box under/in your dash, as they are generally attached to the evaporator coil. With a pressure test gauge set, one can quickly determine if the expansion device is working correctly or if the system is just low on Freon. Rarely, they can fail, and they require a lot of work to change.

Do note that every AC system, car or other, must have a correctly operating expansion device. The pressure drop across the device is what makes the "cool" happen.

If the one shop that said the expansion valve is bad did not really hook up a test gauge set, they could be setting you up for a large "repair bill" when in fact all they will actually do is routine test, evacuate, and re-fill, commonly called an AC tuneup. The no-charge is a clue. If that shop have attempted work, they are unlikely to give it to you gratis, more likely they'd charge you a diagnostic fee. A tuneup would run around $100.

Consider taking it to a third place and have them investigate it. Worst case, I'd rather burn a $100 tuneup as a first step before I'd pay for a $750-$1000 expansion valve. It might just be a frozen expansion valve whose operation will return to normal after any moisture is removed during the evacuate step. Getting rid of moisture is what the evacuate is all about.

dknightd
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Re: DIY AC freon for car or professional fill up

Post by dknightd » Tue May 15, 2018 6:48 pm

I'd slowly put in a can of the walmart stuff, and monitor the air temperature from the vents. Keep an eye on the can reported pressure, but it only measures one side, the thing you want to monitor is the temperature from the vents. If that did not fix it I'd take to a Toyota dealer. It could be the AC is working fine, but a mixing valve is broken. Good luck.

Rotarman
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Re: DIY AC freon for car or professional fill up

Post by Rotarman » Tue May 15, 2018 7:05 pm

Had a small leak around compressor in a car that wasn't worth much and figured $20 per season was better than $200 or so to have it replaced as the car was 15 years old. I used half the can and it blew like ice that summer. 4 years later it still blows like ice and the half full can sits on a shelf in my garage.

ncbill
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Re: DIY AC freon for car or professional fill up

Post by ncbill » Wed May 16, 2018 5:37 am

Valves also leak over time.

Took a couple of summers (putting in the UV dye each time) for my local independent mechanic to figure out the low-pressure valve was leaking.

Just had the same thing happen (with the high-pressure valve) on my home A/C (well, heat pump)

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jharkin
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Re: DIY AC freon for car or professional fill up

Post by jharkin » Wed May 16, 2018 6:12 am

Agree with everybody else... there *is* a leak somewhere.. AC systems are close to hermetically sealed and very rarely just loose pressure with age.

It depends on if its worth spending the money to fix it right or not, you could recharge and get another season... or maybe longer... or maybe it wont help at all.

PrettyCoolWorkshop
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Re: DIY AC freon for car or professional fill up

Post by PrettyCoolWorkshop » Wed May 16, 2018 6:45 am

misterno wrote:
Tue May 15, 2018 3:31 pm

I took my car 2 different shops, one said the valve behind the dashboard is stuck and my freon is full to the top so no charge needed. This did not make sense because the air volume is good

Second place said there is no leakage and freon level is low and they need to fill up freon. So I asked about the AC kits they sell in walmart for 20-30 bucks. They said, those only work for one season then it will blow warm air again. They also said, the AC system has to be completely emptied and make sure there is no moisture or anything in the tank and then fill up freon. This will enable cold air blow for many years
The two statements by the different shops are contradictory. You therefore can't necessarily trust either of them and you should diagnose it yourself.

As a quick rundown of how to diagnose it, there are two ports that you can connect to on the A/C system. High side pressure and low side pressure. The way the system works is that the fluid starts as a cool low pressure gas, goes through the A/C compressor, becoming a hot, high pressure gas, then goes through the condensor, becoming a lukewarm high pressure liquid, then goes through the expansion valve, becoming a cold low pressure liquid, then goes through evaporator, becoming a cool low pressure gas. Then it restarts it's journey.

All you care about when you hook your manifold gauge set up to the high and low side pressure ports is pressure. When the car is off, and there is enough freon, the two ports should have equal pressure, because the high side slowly bleeds down to the low side if the compressor is not running. This pressure should be about 75 psi but will vary based on ambient temperature. If the system is essentially empty of freon, this pressure will be much less than 75 psi. If the system is partially empty, the pressure will still be about 75 psi because as long as there is enough freon to make liquid freon on the high side, the system will act largely the same.

So now you can turn the car on and crank the A/C to max coldness and max flowrate. Look under the hood and make sure that the compressor is running (this is actually tricky to be sure of for a newbie. The compressor runs off of a pulley, but the pulley has a clutch in it. the outside always spins, but the inside has to spin for the compressor to actually run) and then look at your manifold gauges. The low side pressure should be about 35 psi and the high side pressure should be about 200 psi, according to this chart:

http://acprocold.com/faq/r-134a-system-pressure-chart/

If both your pressures are low, add refrigerant. If your low side is high and your high side is low, it means that your compressor is barely doing any work and needs to be replaced. If the low side is low and the high side is high, it means the expansion valve is probably stuck shut and needs to be replaced.

Easy peasy! Never trust a mechanic. The fact that the two different diagnoses from the two different shops should tell you something.

misterno
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Re: DIY AC freon for car or professional fill up

Post by misterno » Wed May 16, 2018 9:59 pm

Update

I went to a local small shop that I always go for inspection sticker. They inspected and found no leak

So I asked "if there is no leak so howcome freon is low?"

He said " it is the coil inside the car that always leak alittle bit no leak in the front. That can not be fixed.

He had this device with blue light on it and he said there is no leak in the front of the car and compressor is good

Anyway he charged me $60 in total to diagnose, empty the tank and recharge fully

I am happy

RetiredAL
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Re: DIY AC freon for car or professional fill up

Post by RetiredAL » Thu May 17, 2018 12:33 am

misterno wrote:
Wed May 16, 2018 9:59 pm
Update

I went to a local small shop that I always go for inspection sticker. They inspected and found no leak

So I asked "if there is no leak so howcome freon is low?"

He said " it is the coil inside the car that always leak alittle bit no leak in the front. That can not be fixed.

He had this device with blue light on it and he said there is no leak in the front of the car and compressor is good

Anyway he charged me $60 in total to diagnose, empty the tank and recharge fully

I am happy
+1 Glad you are happy and that price was good! You now have a mechanic that deserves getting your future work.

wrongfunds
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Re: DIY AC freon for car or professional fill up

Post by wrongfunds » Thu May 17, 2018 7:55 am

+! Next time, do not shop for repair service (aka don't go to another shop which sends you $15 oil change coupon in mail!) anywhere else. First take it there. if he tells you to go to dealer, then only go to dealer.

We as customers need to keep honest shops busy and thriving and it is our duty to avoid the shops which are not.

misterno
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Re: DIY AC freon for car or professional fill up

Post by misterno » Thu May 17, 2018 9:00 am

Update

AC is blowing ice cold so it is working fine.

Why is my car acting like it has more horse power now? I noticed it is much more powerful.

Does that make sense?

wrongfunds
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Re: DIY AC freon for car or professional fill up

Post by wrongfunds » Thu May 17, 2018 10:00 am

Does that make sense?
NO.

But there could be other factors.

for example, the shop might have checked and filled your tire pressure to the specification.

The end of winter fuel at the pumps. I routinely notice difference in all of my cars when the changeover happens.

Teague
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Re: DIY AC freon for car or professional fill up

Post by Teague » Thu May 17, 2018 11:51 am

wrongfunds wrote:
Thu May 17, 2018 10:00 am
Does that make sense?
NO.

But there could be other factors.

for example, the shop might have checked and filled your tire pressure to the specification.

The end of winter fuel at the pumps. I routinely notice difference in all of my cars when the changeover happens.
Or the weather simply got a few degrees cooler while the car was in the shop.
Semper Augustus

NHRATA01
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Re: DIY AC freon for car or professional fill up

Post by NHRATA01 » Thu May 17, 2018 1:20 pm

misterno wrote:
Thu May 17, 2018 9:00 am
Update

AC is blowing ice cold so it is working fine.

Why is my car acting like it has more horse power now? I noticed it is much more powerful.

Does that make sense?
If the A/C is properly charged the A/C will cycle on and off more frequently. If it's low, the compressor may run and run and run, which is additional parasitic drag on the engine. Though to be honest I have a hard time thinking it would be overtly noticeable.

wrongfunds
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Re: DIY AC freon for car or professional fill up

Post by wrongfunds » Thu May 17, 2018 3:34 pm

Be glad that it is NOT the other way around!

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