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Discussion Starter · #1 ·
Have a 2004 arc and the ac works but doesnt get as cold as I would prefer and in San Antonio right now its hot as hell. So my question is: the psi on the low side is now 43, is this enough for 100-105 degree weather w stupid humidity? when I charged the system it was at 22, after a can of refrig. it reached 43 and Ive been checking to see if drops and it hasnt at all. Also should I put oil in the system? I know your supposed to put it first in an empty system but ive also heard its ok to some to top off. any help would be appreciated
 

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Directly from a technical school professor the best way to test if your system is properly charged is to get an equal temperature reading on both the high and low lines at the firewall. I believe thats what I remember being told,lol. You can either try to borrow the proper meter for reading this temp or find someone with the laser type temp sensor. Good luck.
 

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Directly from a technical school professor the best way to test if your system is properly charged is to get an equal temperature reading on both the high and low lines at the firewall. I believe thats what I remember being told,lol. You can either try to borrow the proper meter for reading this temp or find someone with the laser type temp sensor. Good luck.
You do not want equal readings on the high and low side. Low side should be between 30 - 40psi. 43 probably isn't hurting anything. The high side psi should roughly be 2 times the temp in F + 50.
 

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Discussion Starter · #4 ·
Is the 30-40psi you mentioned specific to our cars or in general? I just read a can of charge at store that said the low side psi should read 55 for 100+ degree temps. not true for a 9-5? My AC was barely cold w 30-35 psi in 102 degree weather
 

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Anything above 50psi on the low side is too much. It means something is wrong.

You shouldn't need to add oil unless there was a massive leak where everything blew out or you changed parts in the system.

You really need high and low side readings to diagnose whats wrong, if anything, with the AC system. Could be the expansion valve is bad, it could be the blend doors inside the car not fully turning to cool.
 

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And the PSI isn't specific to our cars, its specific to the type of refrigerant being used, r134a. All AC systems from r134a, r12, NH3 or anything else all operates on the same principles, but under different pressures.
 

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Discussion Starter · #8 ·
ok thanks i'll get a reading on high side. also I've noticed a couple things: the rear vents are perfect air comes out real cold and nice so why won't the fronts? cabin filter maybe? and the acc will not always display "auto" even if I press auto. thanks for your time and help. I'm close to just taking it in but the cool air and low mileage is making me think it isn't anything serious.
 

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Press the auto and off button at the same time on the ACC and see what codes pop up. It sounds like a blend door issue, not and AC issue
 

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Discussion Starter · #10 ·
Press the auto and off button at the same time on the ACC and see what codes pop up. It sounds like a blend door issue, not and AC issue
Tried for fault codes before and after charging and got a zero.? Blend door would throw a code?
 

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I am in a similar boat to the OP. The A/C on my '04 works, but takes 20+ minutes to reach cooling potential after sitting in the sun on a hot day. Even then, it blows cool air, not cold air like our other cars. The cabin filter is clear, the blend door is not broken, and there are no ACC codes.

I am at 35 PSI on the low side, but I don't have a full fledged manifold to test both high and low side right now. I am planning on buying a manifold so I can get a better idea of what's going on.
 

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Tried for fault codes before and after charging and got a zero.? Blend door would throw a code?
Yes, the blend door should throw a code. Its strange that the back would blow cold and the front wouldn't. Does the passenger side blow cold as well. I believe the rear vent is connected to the passenger side.
 

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Just went through a lot of these issues...so I stopped by the shop he added some refrigerant and as soon as it went into the system it started working, the system will not run if you are low on refrigerant, I must have have just been low and now I will be observing to see if the system stops cooling again and at that point I will know if I have a leak. I am pretty sure he had the low side at 50 psi.
 

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I just charged my son's system yesterday. Since I didn't know what to set the charge to, I hooked up my manifold to my 03 Aero and read what was there. About 40 on the low side, 250 on the high side (it was 90-degrees plus that day)

I added refrigerant to his car to get to 40 and 250, all seems well.


his car had a leak, one of the o-rings on the hoses that connect to the compressor. I repaired that when we had his turbo out but hadn't refilled. The system was open, there was nothing in it, but I didn't have any oil leak out so I didn't put oil in when I refilled. I read somewhere that if you are going to change the oil you need to take the compressor off and drain it. Didn't feel like it.

Should I have added oil to the system before refilling? I did pull a small vacuum just to check the system and it held. The AC seems to be working pretty good on his car right now. (But it did not take a "full charge of 875 g" before it got to 40 low and 250 high)


PS. I bought a manifold set on ebay for something like $30, a great investment in my mind. You'll need the R134a quick connector adapters which are extra on some and come with others. When I was filling the system I used one of those cheap trigger-based adapters that I got at the auto parts store to empty the 12-oz cans of refrigerant.
 

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Discussion Starter · #15 ·
I just charged my son's system yesterday. Since I didn't know what to set the charge to, I hooked up my manifold to my 03 Aero and read what was there. About 40 on the low side, 250 on the high side (it was 90-degrees plus that day)

I added refrigerant to his car to get to 40 and 250, all seems well.


his car had a leak, one of the o-rings on the hoses that connect to the compressor. I repaired that when we had his turbo out but hadn't refilled. The system was open, there was nothing in it, but I didn't have any oil leak out so I didn't put oil in when I refilled. I read somewhere that if you are going to change the oil you need to take the compressor off and drain it. Didn't feel like it.

Should I have added oil to the system before refilling? I did pull a small vacuum just to check the system and it held. The AC seems to be working pretty good on his car right now. (But it did not take a "full charge of 875 g" before it got to 40 low and 250 high)


PS. I bought a manifold set on ebay for something like $30, a great investment in my mind. You'll need the R134a quick connector adapters which are extra on some and come with others. When I was filling the system I used one of those cheap trigger-based adapters that I got at the auto parts store to empty the 12-oz cans of refrigerant.
it is my understanding that oil should be added before charging in an empty system But please if you cannot contribute to my original posting and have issues or questions start a thread of your own so it gets the proper attention and doesnt take away from mine. thanks
 

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Discussion Starter · #16 ·
Yes, the blend door should throw a code. Its strange that the back would blow cold and the front wouldn't. Does the passenger side blow cold as well. I believe the rear vent is connected to the passenger side.
the front blows cold just not as cold as back or,yes, passenger.
 

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Discussion Starter · #17 ·
Just went through a lot of these issues...so I stopped by the shop he added some refrigerant and as soon as it went into the system it started working, the system will not run if you are low on refrigerant, I must have have just been low and now I will be observing to see if the system stops cooling again and at that point I will know if I have a leak. I am pretty sure he had the low side at 50 psi.
think im going to try to add r134 to reach 50ish
 

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it is my understanding that oil should be added before charging in an empty system But please if you cannot contribute to my original posting and have issues or questions start a thread of your own so it gets the proper attention and doesnt take away from mine. thanks
not for nothing but kind of childish. People come here for a variety of answers and what I added was related to "AC Charge" is it not?

And I *did* answer your question that my 03 Aero had 40/250 on a 90-degree day and the AC there works fine and has been that way for years. That was the baseline that I used to charge the other car.
 

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Discussion Starter · #19 ·
not for nothing but kind of childish. People come here for a variety of answers and what I added was related to "AC Charge" is it not?

And I *did* answer your question that my 03 Aero had 40/250 on a 90-degree day and the AC there works fine and has been that way for years. That was the baseline that I used to charge the other car.
Sorry I didn't intend to come off childish at all plus I answered your question. I may be new to this forum but not to forums in general. I personally wouldn't ask questions in someone else's thread regardless of whether or not its related. Out of common courtesy. Your questions would have a much greater chance of being answered if you started your own thread.(or even read mine since your oil question was addressed already)
 

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Anything above 50psi on the low side is too much. It means something is wrong.

You shouldn't need to add oil unless there was a massive leak where everything blew out or you changed parts in the system.

You really need high and low side readings to diagnose whats wrong, if anything, with the AC system. Could be the expansion valve is bad, it could be the blend doors inside the car not fully turning to cool.
Very true, complete diag cannot be done without both gauges hooked up. Here is a link that shows a pressure chart for auto A/C.
http://www.idqusa.com/faqs.php?faq=74&faq_id=74&category_id=18
 
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