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ISX

Here are all of the components of the 2nd Gen A/C system, and what they all do.

First is the compressor. The refrigerant is compressed making it even hotter, it becomes a high pressure high temperature vapor.

http://www.mopar1973man.com//isx97/Truck%20Stuff/Ryan's%20Dodge/Under%20Hood/AC/IMG_1471.JPG

After turning into a high pressure high temperature vapor, the refrigerant goes through the condenser. The condenser has ambient air running through it which cools off the superheated refrigerant, so much so that the refrigerant turns back into a liquid. Nevertheless, the refrigerant is still pretty hot and remains at high pressure.

http://www.mopar1973man.com//isx97/Truck%20Stuff/Ryan's%20Dodge/Under%20Hood/AC/Condenser.jpg

Now we make the refrigerant cold. To do this, it goes through an orifice tube. The orifice tube (not to be confused with an expansion chamber) has an orifice that holds back the pressure in the condenser and also allows the pressure to build, if there wasn't a restriction from the orifice, the condenser would quickly lose all of its high pressure and wouldn't do it's job. The orifice tube allows a metered amount of flow to go through it, and then expands into the hose that goes to the accumulator, becoming very cold. One side will be hot, the other will be cold. It will also now be low pressure. This can be seen with an air compressor when you blow air out of a hose. The air expands instantly and is cooled, that is why the air feels so cold coming out of that air hose.

http://www.mopar1973man.com//isx97/Truck%20Stuff/Ryan's%20Dodge/Under%20Hood/AC/Expansion%20Valve.jpg

It then proceeds into the Accumulator or Dryer. This stores the freon and also has things in it to help dry out the freon to prevent any moisture from building up.

http://www.mopar1973man.com//isx97/Truck%20Stuff/Ryan's%20Dodge/Under%20Hood/AC/IMG_1470.JPG

The last step is the Evaporator. This is inside the cab and air is blown through it, giving you cold air out of your vents. Technically speaking, it is absorbing heat into the refrigerant which then turns the liquid refrigerant back into a low pressure gas as it warms.

They get stuff built up in them, as mine has.

http://www.mopar1973man.com//isx97/Truck%20Stuff/Ryan's%20Dodge/Interior/Dash%20and%20Vacuum/IMG_1192.JPG

So now that the refrigerant is a low pressure hot gas, it is sent back to the compressor to compress it into a high pressure, very hot, gas that has much more heat to be released in the condenser. If it was a low pressure gas, there wouldn't be enough volume through the condenser to keep you cool, it would also not be hot enough to release enough heat to keep you cool. So you compress it to make it really hot, the condenser has a ton of heat it easily expels, and the refrigerant expands back into a low pressure fluid that is very cold, and you have an efficient a/c system.

Ambient temp influence the pressures of the high and low side.

Here are 2nd Gen Pressures, taken from http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/27-hvac-heating-ventalation-and-air-conditioning/58-recharging-air-conditioning-with-r134a-freon

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Vent temps..

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guesswho512

sticky anyone...i'll add a tidbit. that chart is missing a little info, you should have ambient temp/ humidity and temp out of the vent. high humidity will have warmer air out the vent because some of the "cool" is absorbed as water vapor condenses.

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ISX

sticky anyone...i'll add a tidbit. that chart is missing a little info, you should have ambient temp/ humidity and temp out of the vent. high humidity will have warmer air out the vent because some of the "cool" is absorbed as water vapor condenses.

I left that out since I was more explaining how it worked rather than vent temp, but I will throw that on there too. :thumbup2: Humidity part will just have to be known. I think the ambient chart is plenty good. I just wanted to get the components labeled for everyone mainly.

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guesswho512

I left that out since I was more explaining how it worked rather than vent temp, but I will throw that on there too. :thumbup2: Humidity part will just have to be known. I think the ambient chart is plenty good. I just wanted to get the components labeled for everyone mainly.

well, if you are looking at this thread, than your probably don't know about A/C systems, or trying to fix yours. humidity plays a large part in output. THIS CHART IS NOT FOR DODGE RAMs post-98-138698167547_thumb.jpg you can see here how humidity can change expected pressures and output of the vent. the percentages on the right is outdoor humidity. i don't want someone to think there A/C is jacked up when its working properly

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ISX

Now that is neat! Good work Guesswho. I might have to get a calculator going factoring humidity in, gives you what pressure is needed high and low to get the desired temp. Sounds like it would take some work but is interesting so I might have to figure out how to do it. Is that chart for R134?

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Wild and Free

I left that out since I was more explaining how it worked rather than vent temp, but I will throw that on there too. :thumbup2:

Humidity part will just have to be known. I think the ambient chart is plenty good. I just wanted to get the components labeled for everyone mainly.

Then I need to correct here.

This system has no expansion valve, it has an orifice tube. Not too many newer systems have expansion valves anymore. most systems use orifice tubes that slip inside the line prior to the evaporator.

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ISX

Then I need to correct here. This system has no expansion valve, it has an orifice tube. Not too many newer systems have expansion valves anymore. most systems use orifice tubes that slip inside the line prior to the evaporator.

Thanks W&F! I wasn't sure with a lot of it, main reason I keep making these component threads :lol: So I changed expansion valve to orifice tube, but do I need to change all the expanding stuff too? I am starting to think it works by having an orifice to limit flow, this limit makes the condenser build very high pressure, the orifice lets the refrigerant out slowly but also goes from a small hole at high pressure to a large area resulting in low pressure and very cold temperatures. Is that correct? I was wondering why the expansion valve pics didn't look like anything on mine, but I knew it was hot and went cold at that orifice tube thing, so now I know why!

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Wild and Free

An expansion valve is nothing more than an orifice also. it is just housed in a larger housing.

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ISX

An expansion valve is nothing more than an orifice also. it is just housed in a larger housing.

Ah, now I got it. Thanks again!

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guesswho512

Is that chart for R134?

yes it is for a vehicle with R134a. this chart came out of 1994 honda accord FSM(the first one i had handy). i noticed the 2001 dodge ram FSM didn't list #'s based on humidity, but has a range of acceptable psi/temps.

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cumminspower

so, how does all that junk get built up around the evaporator even though it's inside the dash.....this seems to be the common failure point in chrysler AC systems.....mine went out after only 3 years....

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burb31

Also, It's my understanding that the accum/drier is the last step, not the evap. It starts at the compressor then to the condensor, to orifice tube then evap then accum/drier and back to comp again. If you cut it in half...it's the hot side from comp to orifice tube. cold side from evap to comp.Maybe this is what you were saying and I read it wrong, my apologies if that's the case or I'm mistaken.It's been quite a few years since I worked on a/c.

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ISX

You're killing me Mike! :evilgrin: Fixed it. Thanks guesswho, good thing you're back around again :lol:

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guesswho512

You're killing me Mike! :evilgrin: Fixed it. Thanks guesswho, good thing you're back around again :lol:

sorry to break your balls but you changed the name of the link,, but its still pointing to the old location...so its still dead. it tries to find mopar.mopar1973man.com...... so basically its still the old link with new text. on a lighter note, its good to be back.

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ISX

I just can't win with this thing. I got it now :doh: Let me know what else you find :lol:

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twentyohtwo

Hi folks! I have been doing commercial refrigeration for over 20 yrs. and thought I would chime in. All refrigeration and a/c systems are basically the same. They do vary when it comes to controls and components but the principle is constant. Here is a quick rundown of what takes place inside the lines of a typical refer. system.Refrigeration is a cycle. Starting at the compressor suction side you have a low pressure low temp gas. The compressor converts it into a high temp. high press. gas. The refrigerant is then cooled in the condenser where it changes state to a high temp. high pressure liquid. The liquid is then sent to a metering device, be it a capillary tube, thermostatic expansion valve, or an orifice. At this point that high pressure high temp liquid is forced through a tiny hole where it instantly loses it's density and pressure and turns into a low pressure low temp. vapor. This takes place at the inlet of the evaporator. When heat from the conditioned space is absorbed by this cold vapor it converts back into a low temp low pressure gas. It then heads to the accumulator which is a protective device for the compressor. The accumulator insures that no liquid reaches the compressor. After the accumulator the low pressure low temp gas heads back to the compressor to start the circuit again.

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