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need to do something, but what?

notsobrite on Fri June 25, 2010 8:43 PM User is offline

Year: 1995
Make: Infinity
Model: G20
Engine Size: 2.0
Refrigerant Type: 134A
Ambient Temp: 85
Pressure Low: 82
Pressure High: 186
Country of Origin: United States

My son left me his car to do some work unrelated to a/c and i noticed the a/c isn't cooling so great. It is in the low to mid 80's and I could only get 66.4 degrees from vent. I got the above readings and thought I should add refrigerant or vacuum and fill. I am a little worried that we tried to jack from the front end and it banged the front pretty good. I don't think there is a relation to his a/c issue but nevertheless it makes me a little nervous. I'm not sure how well it was cooling when I got it. I have read it is not a good idea to top off 134A systems. Obviously i am a newbie. Any ideas??

notsobrite on Sat June 26, 2010 9:10 AM User is offline

Could someone tell me 1. What the proper low and high side readings should be for this vehicle?
2. Is it a good idea to, after successful deep vacuum, to use a can of refrigerant which also contains 1 oz. or so of pag100 oil? thanks

Dougflas on Sat June 26, 2010 10:27 AM User is offline

It is not a good idea to add oil without knowing what the amount of oil currently is in the system. If too much oil is in the system, that takes up "space" that the frigerant show occupy. Generally. low side should be 30psi and high side 225 psi is a ball park figure.

Briandl79 on Sat June 26, 2010 5:12 PM User is offline

I don't think it's ever a good idea to use refrigerant that has anything in it except refrigerant. Does your system even use PAG100, and if it does the can most likely contains more than just oil, which you don't want in your system (leak sealers, etc).

Looks like your low pressure is pretty high, high pressure a little low. I definitely wouldn't top off a system with that high of a low side pressure.

I'm sure we'd all be interested to hear exactly what you accidentally did to the vehicle, and if anything else has been done to the A/C system previously.

notsobrite on Sat June 26, 2010 7:46 PM User is offline

There is a reason the name is notsobrite. My initial readings must have been incorrect. I used a Mastercool gauge set no. 98660 which has psi on outer ring and Fahrenheit scale in blue on an inner circle. The needle has a sharp long point on one end which reaches the outer edge of the gauge and the psi scale. The blue Fahrenheit scale is crossed by same end of needle but at opposite end pointed out by the opposite, triangular shaped short end of the needle. I must have been looking at the numbers on the opposite end of the needle, confusing them for psi. If that is the case, the psi numbers may have been low 10 and high 150. Anyway, I vacuumed the thing three times to around 29 and it seemed to hold for about an hour the last time. I proceeded to add R134A and I believe I ended up with about 28 oz of refrigerant. the final numbers at around 2000 rpm were about 26 on the low side and close to 275 psi on the high side. The ac is cooling to around 47, much better than before. I still am puzzled by the use of the Fahrenheit scale, how to read it and its purpose. As for the banging the underside of the car. We foolishly had a floor jack on a cross member in the front under the radiator which also had a support running from the front towards the back. It seemed pretty sturdy, but as we raised the jack it slipped towards the front and with a bang ended up under said location but also some sort of rolling pin support running left to rt across the front. I could see no visible sign of damage. Am I finally reading the gauge right using the needle that reaches the outer psi scale? Is the 275 on the high side too high? What is the Fahrenheit scale for? sorry to be "notsobrite" thanks

ACProf on Sat June 26, 2010 8:37 PM User is offline

The outer scale is PRESSURE - in PSI as you know.

The inner blue scales are the TEMPERATURES of specific refrigerants at that pressure. They are all different.

SO, if the needle points to 26 PSI, the temperature of the R134 in that line will be where the needle passes over the blue R-134a scale.

Same for the RED gauge except for the higher and hotter temperatures associated with the condenser.

Not everybody knows that - but now YOU do. That should "brighten" your day.

notsobrite on Sat June 26, 2010 8:56 PM User is offline

Thank you so much for the enlightenment. I still worry about the high side number being maybe too high. thanks again.

bohica2xo on Sun June 27, 2010 3:24 AM User is offline

Clean the condensor air path. Make sure the fan(s) are working properly & at the right speed.

Bugs, dirt, etc. build up in the condensor fins. This will contribute to the high side pressures. Spray a good surfactant like Simple Green or Zep Orange deep into the fins on a cold condensor. Let it soak for a few minutes, then flush it with a garden hose.

You can check for condensor airflow issues by misting water on the condensor, and observing the high side pressure. If a little water makes the pressure drop like a rock, you have an airflow issue.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

notsobrite on Mon June 28, 2010 3:20 PM User is offline

Last night i took a (hot water) garden hose and cleaned the condenser as best I could without taking a bunch of stuff apart. I put the gauges on and in the process of attaching the high pressure side I lost some oil and refrigerant (yellow in color?) I am finding that I'm not too great yet at attaching it without losing some. Fortunately I have been wearing safety glasses and gloves. With some variation, the needle seems to stabilize at about 24 on the low side and 230-240 on the high side when compressor is engaged. Thermometer in front of condenser is at about 84. Blowing about 45 degree air with door open and blower on high. The compressor on this old car has been noisy since my son bought it six years ago. Especially when compressor off. What do you think. Do I need to work for better numbers? I am satisfied with the cooling temp. I worry that I may have let too much escape but don't know. Should i vacuum down and start all over. Should I try to top it off a little bit? Should I quit and hope for the best? thanks

Briandl79 on Mon June 28, 2010 7:19 PM User is offline

Your gauges don't back off like this:

Edited: Mon June 28, 2010 at 7:20 PM by Briandl79

notsobrite on Mon June 28, 2010 7:37 PM User is offline

Briandl79 on Mon June 28, 2010 7:43 PM User is offline

To answer your question, sometimes it's better to quit while you're ahead. If you look through these forums you'll find a few people that had good numbers but kept trying for better, and wound up overfilling. 45 degrees for a fifteen year old car isn't bad at all, and the thing is, it's going to blow even colder once you get it on the street, especially the highway.

Edited: Mon June 28, 2010 at 7:44 PM by Briandl79

notsobrite on Mon June 28, 2010 7:43 PM User is offline

Thanks for the video. However my quick connect does not have the blue knob to tighten. It only has what is typically on air compressor and pressure washer lines. A round sleeve to pull back and release. I think I will get the hang of it. thanks again. I still am wondering whether I should be satisfied with the pressures the way they are. Any more comments will be appreciated.

Briandl79 on Mon June 28, 2010 7:55 PM User is offline

I don't like those kind, it's easier to mess up the shrader valve.

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