Well, the A/C was acting strange the other day so I put a guage on it and it was way low on refrigerant. I put the two cans that I had in and the guage moved up a bit each time but didn't get into the Blue zone which is optimum. I went and got two more cans figuring I'd need one and save the other for the future. At this time the A/C was blowing cold but I figured I'd get it right. I even pulled the guage off and put it on the wife's van and the needle moved to the exact top of the blue zone so i figured the guage was not malfunctioning. I ended up putting both of the new cans in even though I thought it may be way too much. The guage still registered a bit less that optimum. I stopped there and didn't even need the A/C till today. I turned it on and it made a godawful sound which went away and it blew slightly cool for a few minutes but never got cold. I turned it off and drove home. I put my guage back on and Whoa Nelly! I'm way up in the red range now and need to purge some of this! I guess the compressor just shuts down when the system is overcharged because it was not engaging at all until I purged a little bit from the system. I don't know what else I could have done when I was filling the system because I had the guage on and off about 15 times. Why would it all of a sudden shoot up so high?

 

Outside air temp can cause this issue. If it is cold outside your pressures will be different than when it is warm. If the truck is warm the pressures will be higher( High side you will see the biggest difference, low side is regulated by the orifice, or expansion block on our trucks). The hotter it is the higher the pressures are. The best way to deal with this issue is to evacuate the system, vac it down, measure and replace oil removed, and recharge system with the proper weight of R134A. It is tough to do it with just a gauge set.

 

Thanks.....

 

Working with R134a is tricky. Very sensitive to temperature variations.

Dodgezilla if you will PM me with your email address I can send you the page out of the Dodge manual with the chart for A/C charging.

MikeyB

 

Thanks MikeyB. I have the manual. I guess I should just look at it. I put the guage on this morning and it was showing that I am at the perfect level in the system. Which one do I believe, hot day reading or cool day reading?

 

I'd be more inclined to believe the hot day considering that that is when your going to use the AC.

 

That was my thought too.....

 

As stated already R134a is very tricky in that a little too much or too little and you will not have maximum cooling. R12 refrigerant was more forgiving in this area. Make sure your condenser is free of debris and condenser fins are in good shape. Another area to look at is the area between the condenser and radiator. I can't tell you how many time a poorly operating a/c was caused by crap in this area. Not saying that this is your problem just letting you know of an area to inspect for maximum a/c operation. Like Spooler said have it evacuated, weighed, charged and leak checked.

Another thing that becomes a problem with not using the proper equipment is that your system may have too much air in it. If the system has too much air in it it can show full, but still not put out cold air.

I work for a large a/c shop and i'm not knocking dealerships, but I am amazed at how many of them bring us their vehicles to diagnose and repair when they throw their hands up and give up.


Just like a barber it all depends on the person holding the scissors as to what type of job you will get.

 

I worked at a Nissan dealership for several years. Always did a good amount of the A/C work(very few comebacks). It's not bad. Just have to pay attention to detail. I did use a gauge set for all of the R12 setups, but I had an evacuation machine and used a vaccum pump. The all in one machines are great. Really makes it easy and no guess work. Did many R12 to R134A conversions. Worked on all the major brands. Hated GM the most. You always had to pre-lub the compressors by hand. Getting it to turn for the first time while adding oil was a pain. Darn things would shell out at the drop of a hat. Rule of thumb, If you break into the system install a new dryer(filter). If you just evac, vac, and recharge not a big issue.