# Low side A/C port



## chiltonRabbit (Feb 14, 2009)

I'm trying to check/refill the a/c refrigerant and I'm not sure which side is which. The chilton manual (i know, i know I should get a bently fsm) says to hook it up to the low side, but doesn't tell you where it is. It also mentions 'WARNING do not hook up to high side'.
I have a 1999 Golf 2.0L and here are the pics:
image A: near the front of the car (smaller fitting)








image B: near the passanger side of the car (larger fitting)









Which side is which?


_Modified by chiltonRabbit at 8:07 PM 2-14-2009_


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## sheimbach (Mar 12, 2006)

i dont know which one is what by looking at the pictures but i can tell you that whatever tool you have will only hook onto one fitting...they are different sized...i can also tell you that you cannot properly service a ac system without seeing both low and high side pressures on a gauge set and having a accurate scale for delivering R134a


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## Mr.Pickles (May 2, 2006)

*Re: (sheimbach)*

here is a quik tell for anyone wondering, run the ac grab the ac lines at both fitting points and which ever one is hot is the high side, cold is low side. but the above post is correct your nozzle will only fit onto one fitting.


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## chiltonRabbit (Feb 14, 2009)

*Re: (Mr.Pickles)*

Is the high side nozzle smaller or bigger?
I have a r134a fitting and the a/c port near the passenger side is too big for it. The one near the front of the car seems too small, but I haven't tried it yet. I just wanted to make sure it was the right one before trying it out.
I'll try out your method as well.


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## chiltonRabbit (Feb 14, 2009)

*Re: (chiltonRabbit)*

Both a/c lines are fairly cool. The high side is actually cooler than the low side. The manual says they should be around 10 degrees F apart.
The low side port is the smaller nozzle and is located in the front.
This one:








I did a pressure check and it's about 28 psi. This is supposed to be normal according to my pressure gauge, but the a/c still runs pretty warm.
I can hear the compressor clutch kick in.
By the way I have a quest r134a recharge hose with gauge handle and the outside ambient air temperature is about 55 degrees.


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## sheimbach (Mar 12, 2006)

high side could be clogged or no pressure...thats why you need to see high side pressures on a gauge, could be bad compressor or clogged receiver dryer


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## chiltonRabbit (Feb 14, 2009)

*Re: (sheimbach)*

So I have no choice but to get one of these:








$155
http://www.amazon.com/CPS-Prod...=8-2


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## sheimbach (Mar 12, 2006)

harbor freight has them alot cheaper...if your not going to use them all the time the cheap one should be ok...but if it turns out that you need to replace parts you also are going to need a recovery machine, a vacuum pump and a scale to recharge your system...it may be cheaper for you to take it to a pro or find somebody with the proper equipment


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## spitpilot (Feb 14, 2000)

*Re: (sheimbach)*

This time 'O year you should be able to cut a deal with AC shop for discount system check/recharge...not too many folks are linin up to have AC work done....particularly with IRS bills comin soon!


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## germancarnut51 (Mar 23, 2008)

*Re: (spitpilot)*

Accidents happen and refrigerant is spilled all the time. It is not against the law, and there is no criminal penalty if you have an accidently leak/spill (everybody would be in jail). You could have an accident before you service your ac system (damn must have a leak, all my refrigerant is gone).
When you are done servicing the ac system, if you have a compressor, you can buy a compressor powered vacuum pump for $13 (on sale) from Harbor Freight, or borrow an ac (wall plug powered)one for free from an auto parts stores that has a tool loan program (AutoZone has a 110vac vacuum pump in the tool loan program).
The Harbor Freight ac manifold gauge set is of decent quality for home use (or light commecial use). All metal, unlike the plastic crap from the local auto parts store. $40 on sale, and you get all the ac manifold with gauges, the hoses, and the valves you need. The only think you will need to buy is the can tap if you are buying cans of refrigerant.
Big Lots (formerly Pic N Save) has 14oz cans of R134a for $4.


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## 2.SlowMK4 (Jan 24, 2007)

*Re: (germancarnut51)*

You shouldn't really work on the A/C system of your car if you're not certified. Just take it to a shop or something and get it done properly. Cause you don't wanna get sprayed with that refrigerant.


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## chiltonRabbit (Feb 14, 2009)

*Re: (2.SlowMK4)*

I would like to repair my a/c system on my own, but if it's more than a simple recharge (adding refrigerant) the cost of tools is way too expensive.








$1500








$50
It's $50 over budget. I think I'll just take it to a pro sometime later this year.
Thanks for all the help fellas.


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## germancarnut51 (Mar 23, 2008)

*Re: (2.SlowMK4)*

What planet are you from?
What is it that you think will happen if some refrigerant touches you? No, you don't die, or get sick, or contract a horrible disease.
Refrigerants are heavier than air, and as such can displace oxygen, so don't work on ac systems in an enclosed space or lay under a car when discharging the refrigerant.
Working on automotive ac system is no different than working on the cooling and heating systems. Simply read the Service Manual, make sure you have the right tools and follow the written procedure. Nothing to it.


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## germancarnut51 (Mar 23, 2008)

*Re: (chiltonRabbit)*

Out here in CA, ac shops charge $100-$150, and insist that they have to do a leak test before they can add refrigerant. 
It ends up costing $200 to add a $ can of R134a.
Personally I find it easier to drag out my gauge set and add refrigerant, than it would be to drive down to someone's shop to pay $200, when I could do it myself in less time then it takes to drive to a shop.
But if you want to blow the $200 (plus $20 a can for refrigerant), instead of $40 for the gauge set, and $4 for the refrigerant, you go right ahead...


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## chiltonRabbit (Feb 14, 2009)

*Re: (germancarnut51)*

Well I've checked the low side pressure and it seems to be fine. So the problem with my car may be more than just refilling the refrigerant (which is definitely easy to do). 
I already have a low side pressure gauge, but not a high side. It could be that the high side is clogged or no pressure (according to sheimbach) and that would mean having to drain the system to test parts. 
I don't want to have to spend money on a recovery machine, a vacuum pump and a scale plus replacement parts to get my a/c working again. It probably would be easier taking it to a shop.
If you have any ideas on how to macgyver the a/c system using only a low side a/c pressure gauge and some basic household materials, then I'm all ears.


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## germancarnut51 (Mar 23, 2008)

*Re: (chiltonRabbit)*

You should not refill without knowing what the ac system is doing, and you can't tell with accurate gauges for both the high and low sides.
So if you refuse to pay the $40 for a ac mainfold gauge set, you need to go to a shop and pay the $150-$200 that they will charge you to pour in a can of refrigerant.
As I wrote to you before, the little gauges are worthless. Your ac system might not have 28 psi, and could still be too low.
And, the pressure reading will only be accurate when the ac system is running continously. 28psi is too low. and the low side pressure will appear high when the compressor is not running, and drop to below the minimum operating pressure when the compressor kicks in. Then the low pressure switch comes into play and cuts off the ac clutch power, so the compressor is disengaged, and the pressure rises back up. When this occurs constantly, it's called "cycling". Adding refrigerant AFTER confirming the pressure will cure this problem.
Just because the blower motor inside of the car turning on does not mean the the ac clutch is engaging to drive the compressor and staying engaged. You need to confirm that the ac clutch is engaged, and the compressor is being driven, before you try to take an accurate measurement of the high and low sides of the ac system.


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## fixmyvw (Mar 28, 2010)

*Re: (germancarnut51)*

Question -- what if the a/c only blows warm air, the compressor clicks upon turning one the a/c, and the clutch seems to be spinning, and the low side port is showing 110 psi. (This is the port near the radiator on 2000 jetta 2.0 L and the one of two which fits the R134a refrigerant dispenser.) Is it dangerous to add refrigerant, or will that correct the pressure reading? What else could cause the pressure reading to go up so high on the low pressure port ?


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## Jrod511 (Apr 29, 2009)

fixmyvw said:


> Question -- what if the a/c only blows warm air, the compressor clicks upon turning one the a/c, and the clutch seems to be spinning, and the low side port is showing 110 psi. (This is the port near the radiator on 2000 jetta 2.0 L and the one of two which fits the R134a refrigerant dispenser.) Is it dangerous to add refrigerant, or will that correct the pressure reading? What else could cause the pressure reading to go up so high on the low pressure port ?


Bump for same question


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## grapper1 (Apr 11, 2010)

*same problem only*

:screwy:I'm having the same problem only difference is my comp. kicks in and out every 3-4 sec.


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