OlatheRX8

I'm looking to check the status of my AC (R134a) system to see if it has enough coolant.

All I have is the cheap set of gauges that allows me to check the low side only.

The gauges come with green/powderblue/yellow/red gauge.

Green: 0-25
blue 25-45
yellow 45-65
red 65-200

All numbers in PSI.

I've looked at the book, and it shows that the 8 seems to have a low pressure side range of 14-22 psi. (or maybe it's really 13 to 21 or so).

The book that came with the gauge says the blue is where you want it. And yet this seems high compared to the 8 manual.

I'm going to try to stick with the manual pressure range rather than the gauge for now.

This would seem to mean that the 8 AC low side pressure is below what is normal for most cars.

Can anyone confirm that this is true?

When I add R143a to the system, do I add it through the low pressure connector? Or is there another connector that I should use?

At this point I have no intention of touching the high pressure side of the system.

I haven't done this before, and I could use some information/reassurance from those who have done this before.

-Mark

=== Update

I've run the test on the low side. And I can see that the gauge bounces from 25 to about 35 depending on if the compressor is engaged or not. (I followed the directions in the 8 manual to the letter.)

This machine hasn't had its AC touched since it was released from the factory. Perhaps this cheap gauge is calibrated to some other standard?

Is there any reason to believe that if I add a little more so that it runs between 30 and 45, that the AC will be any noticeably cooler? Or is that just wishful thinking?

I'm holding off doing anything until I hear from those with experience.

Thanks,
Mark

ken-x8

Do you think there's a problem? I presume you've stuck a thermometer in the vent inside the car and the air isn't cold. And that the compressor is running, etc.

Definitely charge through the low side, the same place you'll measure the pressure. That's all you need to deal with if the problem is just low refrigerant. Never connect a can to the high side. Read the directions on the can - it should have tips on how to purge air from the hose when you connect it, so that you don't contaminate the system.

I don't know what the pressure range is for the 8, but I'd err on the low rather than the high side. R134a systems are not supposed to do well with too much pressure.

I suggest picking up an AC thermometer - which you should find the same place you got your gauge - and monitor the temperature coming out of the vent as you charge. Add a bit at a time, and when it gets to the right temp you've got enough.

Ken

OlatheRX8

Ken,

Thanks. The reason I was looking into this was because I "believe" that my system no longer cools as well as it did. And I had originally thought it didn't cool very well when it was new either.

I gather you think the temp of the cool air is more of a indicator about whether it needs more R134a rather than the low pressure gauge indicator?

I guess I'll need an "objective" way to determine if it is or isn't getting cool enough. I see that there is a chart on 07-10-3 that should give me the appropriate cool air temp reading based on the outside temp of the car.

I'll go find a temp gauge now.

Thanks for the feedback. I appreciate it.

-Mark

ken-x8

Both the pressure and the outlet temperature matter, but ultimately you care about the temperature of the air. Checking the temp avoids opening the refrigeration system before you need to. The shop manual has a chart of the temperature (43 to 46 F for outside ambients up to 86 F, then higher on hotter days). I assume that's the chart you've found.

If the temp is high, then it's time to start on the refrigerant.

Ken

Georgia8er

Reading the pressure may not tell you much on an R134a system. It takes very little less or more than what the system needs to cause less cooling efficiency.

Ken is right on about checking the temperature of the vent air. Not sure if the shop manual says to have the A/C on recirculate or outside air, but do both and hit the freeway. Also, be sure not to let your car sit in the sun a long time before testing, as especially with leather seats this will skew your readings on recirculate.

ken-x8

[QUOTE]Is there any reason to believe that if I add a little more so that it runs between 30 and 45, that the AC will be any noticeably cooler? Or is that just wishful thinking?[/QUOTE

What you measured is already higher than the manual says it should be. There are other things that can fail in an AC system. I think you need to take it to an AC shop.

I remember pumping three or four cans of R-12 (back when it was a buck a can) into my wife's Hornet, with no luck, sight glass still bubbly. Took it to a shop, where they found that the metering valve had gone bad.

Ken

stanknasty56

i may be a little rusty on the subject, its been about 4 years i messed with ac, but the gauge should say what it can read, it should be in the center and it will say r134a or r22....ect. and when u get the r134a do not get it form a store u need to get actual r-134a, it will come in a green cylinder, u can get it from anyone that has a epa licence, but the main point that u need to figure out if u are low on r134a that there is a leak and u need to figure out where it is. hope this helps

nycgps

iTrader: (1)

Check the vent temp first

its pretty easy

go buy a dry-bulb thermometer. its cheap.

put it at the center vent.

turn your car on

warm it up, then keep it at 1500 rpm.

turn it to Max speed (4th)

run it in re-circ mode

set the temp to the coldest

change it to vent mode

now close all ur doors and windows and moon roof.

wait a bit for your AC temp to stabilize.

after its stabilized, check the dry-bulb meter for the temp.

look at the ambient temp.

if outside temp is about 50-86f. your AC vent should be around 43-46. if its 86 or hotter. AC vent shold be something like 46 and higher.



*edited*

I just re-read your first post. hmm. unless your outside temp is over 104f, your low pressure should NOT be higher than 24 psi.

Usually a "proper" R134a Gauge can read at least 300 psi on the "high" side. so your gauge will NOT be able to properly read the high side (you said highest is 200. dont connect it, its gonna blow it up)

So yes, your system, for some reason, is not working right. higher pressure than spec will actually lower your cooling efficiency. or you might need a new dryer. or something else.

if you really want to do this "properly" you will need a better gauge. a vacuum pump, and some other stuff I can't remember right now. a good A/C gauge will cost you about 100 bux. you need a Vacuum pump that can pull around 30 mg. you can probably get one at habor freight for maybe less than 100 bux. "real" r134a. and some other misc stuff.

so I suggest you to pay someone to "release/recycle" some of your R134a. cuz it doesnt sound like you know what you're doing.