Air conditioning pressures

[Gordon Maney]

My 2001 Ram 2500 lost its A/C from the passage of time and normal leakage. It worked great up until a year ago without ever having been charged. Then in a year it went way down.

A friend had gauges, vacuum pump, and so on, so tonight we put three, 12 ounce cans in it after evacuating it. It now cools roughly 25 degrees below ambient and works very well.

The manual says that for the temperature today the low side should have been 50-60 and the high side should have been 215-270.

The pressures we got were 42 for the low side and 310 for the high side. What do the experienced A/C folks here think about that? Do I have a problem?

[MoparFreak69]

Sounds to me like you have an orifice that is slightly plugged up. If a system is empty like that you should always just go ahead and replace all the seals, the accumulator(dryer) and clean/replace the orifice before vacuuming and filling with freon. What is happening is that your low side is pulling the pressure down because it cant pull through the slightly plugged orifice very well. This is also evident with your higher high side pressure.

A good working, modern R134a AC system should cool to at least 40* under ambient temperature. That is the temp we shot for when installing AC into Bobcats at the dealership I worked at. Almost every system I have ever recharged, after performing proper system maintenance, cooled quite well.
I hate to break it to you but you are probably going to have to open the system and replace a few parts to make it work effectively and to extend the life of the components.

*edit* NAPA shows the accumulator for about $40. The orifice is not removable, the tube that contains it runs about $45. A complete O-ring set is about $20. That is about all the serviceable parts you have to worry about.

[Gordon Maney]

Sounds to me like you have an orifice that is slightly plugged up. If a system is empty like that you should always just go ahead and replace all the seals, the accumulator(dryer) and clean/replace the orifice before vacuuming and filling with freon. What is happening is that your low side is pulling the pressure down because it cant pull through the slightly plugged orifice very well. This is also evident with your higher high side pressure.

A good working, modern R134a AC system should cool to at least 40* under ambient temperature. That is the temp we shot for when installing AC into Bobcats at the dealership I worked at. Almost every system I have ever recharged, after performing proper system maintenance, cooled quite well.
I hate to break it to you but you are probably going to have to open the system and replace a few parts to make it work effectively and to extend the life of the components.

*edit* NAPA shows the accumulator for about $40. The orifice is not removable, the tube that contains it runs about $45. A complete O-ring set is about $20. That is about all the serviceable parts you have to worry about.

Thank you. So, should the system not be run at all before this occurs? When you mention extending component life, you are meaning, primarily, the compressor?

Where all [generally] do all the O-rings go? Just at the connection points for the two components you mention? ....or other places, too?

At one time I did a lot of A/C work, but the last time I did was 1975!

[Doc Dave]

Gordon,
This is not a direct answer to your question but is related to your problem. As you know I have the same year/model truck. The truck slowly lost refrigerant gas also. In my case the mechanic (my neighbor) introduced dye into the system and could not really find the leak easily, but if I recall he could just barely make out a trace of it down below where the evaporator was using the special light for this.
We took the dash off and found that there were a few leaves and debris down there and then saw the dye where the evaporator had corroded, leaking out the gas. While everything was apart we also replaced the heater core, as it was quite a job to pull the dash so I did not want to have to do it anytime soon again.
Is it possible something like this is the source of your gas leak?

[Gordon Maney]

Gordon,
This is not a direct answer to your question but is related to your problem. As you know I have the same year/model truck. The truck slowly lost refrigerant gas also. In my case the mechanic (my neighbor) introduced dye into the system and could not really find the leak easily, but if I recall he could just barely make out a trace of it down below where the evaporator was using the special light for this.
We took the dash off and found that there were a few leaves and debris down there and then saw the dye where the evaporator had corroded, leaking out the gas. While everything was apart we also replaced the heater core, as it was quite a job to pull the dash so I did not want to have to do it anytime soon again.
Is it possible something like this is the source of your gas leak?

I don't think the loss of refrigerant over the years since 2001 resulted from anything other than normal loss. It did remarkably well to last as long as it did.

[Tom Petroff]

In my opinion you may be just a bit overcharged.
When you say 3 cans refrigerant, does that equal or exceed the
refrigerant system capacity on the A/C Info. decal?

If it's working good and sounds like it is by your temperature reading You have no other problem other than your gauge reading a little high.
If your total charge is the same as the capacity amount I mentioned earlier then leave it alone.
If you put more in than called for, let a little out.
One other thing is, that when recharging or performing a performance check you must make sure the condenser and radiator fins are clean., and put a floor fan in front of the radiator to aid in cooling.
It keeps the head pressure more realistic.
Also book gauge reading are a guide line and will vary with temperate's and Humidity levels in a real world situation.

One other thing,the space between the inter cooler and radiator on these truck will accumulate grease and dirt badly due to the front engine mounted road draft tube.
Looking down from the top between the two with a flashlight you can see it.
Ideally it's best to remove everything and clean,but a good soaking of engine de greaser then washing out the fins withe a hose works well.
Avoid High pressure washers so as to not bend and close up the fins.

TGP

[MoparFreak69]

Thank you. So, should the system not be run at all before this occurs? When you mention extending component life, you are meaning, primarily, the compressor?

Where all [generally] do all the O-rings go? Just at the connection points for the two components you mention? ....or other places, too?

At one time I did a lot of A/C work, but the last time I did was 1975!

If it were mine, I would not run it until I could get a chance to get the parts replaced and all of the moisture completely out of the system (the accumulator contains dessicant to absorb any moisture that isnt boiled off in the vacuum procedure). Compressors DO NOT like moisture one bit. Think of it this way, if the compressor goes, you are going to have to replace everything in the system. It will send pieces of material everywhere that will eat up the next compressor you install. You cannot clean the insides of anything effectively, it all has to be replaced.
You are correct, the o-rings only go between connection points (hoses to compressor, Hoses to condensor, etc). The orifice is inside of a hose and has to be replaced as a unit like I mentioned in my other post.
You know the saying, if its worth doing, its worth doing right. This is not one of those cases where close it close enough. The manual lists ranges for readings for a reason, they designed the system to work within that range.