A/C charge on 2002 gm 3.1 v6

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My 2002 Buick Century is blowing warm air on drivers side and cooler but not cold on passenger side. I want to check the charge and see if it's low. I can't find a psi rating for it. It states 2.25 lbs is all. I have a gauge but don't know what's normal for this vehicle.

Is there any range at around 75F I should be seeing to deter if it's low

Not enough money to take to a shop at this time.
 
The actual specs for that car are 25-42psi low side and 109-180psi high side @ 65-75°F ambient. The temp of the left center vent should be under 59°.

At 75° you should be closer to the high side of the range depending on humidity.

From 76-85° ambient the range is 28-46psi low side and 139-212psi high side. Vent temp should be under 65°.
 
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That's a pretty large range. Can someone confirm my findings that the high side is on the firewall in the center and the low side is under the drivers side strut brace?
 
That sounds right on the fittings. The high side will be the smaller of the two lines.

It breaks the pressure range down a little more by humidity but that is the overall range they give.
 
I think I got it backwards the large one is on the firewall the small one is on the strut brace. Some genius left the cap off the low side I spent some time getting it clear with shop towels the best I could going to measure the low side pressure soon.
 
Right now it's 81F with 55% humidity. Without a high side gauge is there a safe low side pressure to stop at?

I hear after 30 psi without a high side gauge your gambling. I don't have a thermometer for the vent though.

By the time I get the gauge on it it's going to be 74F and 63% humidity according to weather data.
 
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The lower the low side the cooler it will blow up to a point. In general a good system will run between 25-35 on the low side. There are a lot of variables though. Is the a/c cycling off?

If it reads up around 50-55 on the low side at idle, but drops when you rev it up a little then the compressor is worn out.
 
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Originally Posted By: 901Memphis
Right now it's 81F with 55% humidity. Without a high side gauge is there a safe low side pressure to stop at?

I hear after 30 psi without a high side gauge your gambling. I don't have a thermometer for the vent though.

By the time I get the gauge on it it's going to be 74F and 63% humidity according to weather data.


Are you checking pressures at idle or at 2000 rpm?
This video may be helpful (also includes a pressure chart):

http://www.youtube.com/watch?v=i9yv0euT7xA
 
It sounds like you are a little low, those cars will blow cooler out of one side when they get low.

It doesn't have dual zone temp controls does it?
 
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Yes it has dual zone climate but both are always set to coldest which is why I thought blend door problems but it's reading low I am going to add a little and report back right away.
 
Whats a thread without pics? First pic is after adding final amount of refrigerant with engine at load and the second pic is at idle. Pressure seems to be higher at idle.

Honestly the gauge didn't move much over the beginging where it was just past 25 but it made a huge difference in temps. I probably only added 6 oz of product to go from 79F to 52F and the right vent is still similar but down to around 39F-40F the lowest i saw.

I guess i probably could have put more in but this is good for the last few weeks of summer.


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Originally Posted By: Chris142
A low side guage is useless w/o a high side guage


Yeah that's why i stopped before something exploded.

What's a good but not too expensive gauge setup?
 
Just about any of them will work. The cheaper ones will be easier to break, but they will get the job done. Some brand gauges may be more accurate, but most gauges are close enough unless they are damaged.

I have a cheap mastercool set that has outlasted several sets of Mac and OTC sets, because of the dummies at my old job breaking them.

This would work. guages I don't like those couplers but it would get the job done.

This looks like the same set I have. link
 
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