A/C not as cool as should be

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Zerpda

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Hello all. 2010 Ram 1500 Laramie AC question. Was wondering if there is a way to tell if you need refrigerant added by other than just having your AC blow warm air? My AC blows cool, eventually. Before I go out and buy something I don't need, I was wondering if there is a way to tell if you are low, is there a gauge you can attach, and if so, what should it read?

Edit: Thank you all for your help. I watched some YouTube video's and went and had the pressure checked. It did come back on the very low end of acceptable. As someone mentioned, I was thinking in cans, and after checking readings, I added about half of a can, to bring the gauges up to the middle point of what is acceptable. It made a world of difference. I did buy one of those vent thermometers to take readings. Prior to the refrigerant addition, it was reading 75". After I added some refrigerant, it dropped down to 50' for the reading. My neighbor has professional gauges. I'm waiting for him to return from vacation to do a proper reading, so that I can top it off if necessary. I saw on one of the video's that the vent temp should be about 10 degree's cooler, but didn't feel comfortable using the mickey mouse gauge that comes with the bottle. Thank you all for your help. Really appreciate it.
 
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Jeepwalker

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Can you plz describe the scenario in a little more detail? When it blows warm ...how long, outdoor temps, the driving conditions when it starts to blow cold?

Here's where little AC probe thermometers can be helpful. Get a couple from Harbor Freight, and put in your center dash vents. Make sure the AC is on vent and max cold. Drive around and observe the temps of air coming out of the vents. If the thermometer temps get down to the mid 40's I would say the problem isn't in the refrigerant, but somewhere else. (vent doors, hole in the firewall (did you run wires through the firewall?, pressure switch, Plugged AC condenser, screen in front of radiator?? etc). There needs to be plenty of air-flow through your truck's radiator also. If you have obstructions like lights, winch, a screen, etc that impede airflow that can hurt AC performance. And bugs and mud too.

If the vent temps hover in the 50's or 60's and never go much lower, and your condenser is clean, then it probably needs a drink of refrigerant. You can check youtube how to do that. There are a lot of how-to videos.

The "ideal" situation is to have an AC specialist hook up refrigerant gauges check discharge and suction pressures. But short of that if you determine it's low on refrigerant, adding some is the cheap way to go. The most common issue on older vehicles is the air conditioning compressor pump seal wears and leaks. Short of a more common (and often visible) line-leak, the compressor front pump seal is the most common leak point. Happens with age/miles. That seal can be changed ...and an AC shop could do it.
 
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CamperMike

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Can you tell if the compressor is fast cycling? Meaning it kicks in then off within a few seconds? You should be able to tell due to engine idle speed changes and may hear a click when it turns on if you have the hood open. If it is doing the fast cycling it is most likely low on refrigerant.
 

Jeepwalker

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The key thing to keep in mind is that there are a handful of things which could affect your truck's cooling besides the refrigerant. Refrigerant is obviously important, and one of the most common problems on an older vehicle (like your truck), but not the only factor. I would recommend watching some youtube videos on what to look for and go through basic troubleshooting steps before adding refrigerant. If you say your truck eventually blow cold air then it might not be refrigerant. If you add refrigerant (when it doesn't need it), then it becomes difficult to troubleshoot the system (adding too much refrigerant will reduce cooling too -- too much isn't 'better').

So... I would encourage you to watch some AC videos first. Most vehicle's AC system is very similar if not nearly identical in parts/pieces (although the components may be located in slightly different locations). Your tk may indeed be low on refrigerant, but at least you would have eliminated a few common things that often trip up people trying to get their AC system to work. And you need to have some airflow across the condenser coil before measuring output.

Note: The AC system is essentially a transfer system of transferring heat from the inside of the cab to the outside of the vehicle ..via the condenser coil ..so insufficient air movement across the condenser coil reduces the system's efficiency -- therefore it doesn't work as good (nor will discharge temps measure as well) by the tk sitting at idle and picking up heat off the radiator. Put a fan in front of the grille, aim the vehicle toward the wind (if it's a breezy day) or take it for a drive when trying to measure discharge temps out the vent.

And bear in mind, you're not actually measuring discharge temps, you're really measuring the amount of heat your AC system REMOVES from the air (heat transferred to the condenser coil). You can't make air 'cold', scientifically speaking the AC system is removing the heat in the air. All air conditioning is like that -- essentially using a refrigerant to pick up heat and transfer it to another location.
 
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Dodge 1500 4X4

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Freon is measured in pounds, you have to have a set of gauges to do this, I would have the system checked by an expert just to have it simply checked over, you can't throw the parts canon at it way to costly, like said over charging can cause damage.
 

crash68

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Freon is measured in pounds, you have to have a set of gauges to do this, I would have the system checked by an expert just to have it simply checked over,
^^^ this
Technically you need to compare the pressure the system is running to the temperatures of the air and refrigerant lines to determine the refrigerant charge.
 

Jeepwalker

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He's probably thinking of adding a can or two to it ...if he's going to do it himself (1 normal-sized can = 1lb). But a lot of driveway DIY guys think in terms of 'cans' ...lol.
 

CamperMike

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He's probably thinking of adding a can or two to it ...if he's going to do it himself (1 normal-sized can = 1lb). But a lot of driveway DIY guys think in terms of 'cans' ...lol.
When I added some to my old Mustang I bought one of the cans with the gauge. That made it easy to avoid overfilling. Now 2 years later I may need to fill it again. I plan to pay someone though to make sure it has the right amount of oil in the system... if you constantly top off you may not have the right amount and eventually damage something. I also noticed the fill valve on that car was leaking slightly... so I want them to replace it as it is simple. Might reduce the leak!
 
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