off the top of your head... 4v A/C and 2v A/C

[NXcoupe]

A little long winded explenation but that sums it up. You did forget about the thermostat at the evaporator. The thermostat measures the evaporator temp so that it does not turn into a block of ice. That is why you a/c compressor is always cycling or turning on and off. Also there is a high presure switch that shuts the a/c system down incase of a part failure. The most common high presure problem you will get is the small orifice getting clogged not allowing the R134a to pass through. That is usually caused by the receiver/dryer desicant getting saturated, breaking apart and going through the system.

In my expiriences with working on a/c systems the high side(Hot red gauge) presures are normally in the 180-200psi range and the low side (Cold blue gauge) is in the 60-80psi range.

It doesn't measure temp it measures pressure iirc. Your evap can turn into a block of ice if you have an issue with the amount of freon in the system for one. Most V8 systems on the 5.0 didn't cycle unless they were low on freon. The 4.6's computer controls the compressor cycling it by the pressure switch. The ones that have a temp sensor don't use an orifice, they use a valve that opens and closes by temp.
No one else took the time to explain how it works, I did, long winded or not, it's better than nothing. And long winded is the 40 pages in the auto tech book.

 

[uncltrvlnmatt]

I used to work on trucks, and they did not have orifices, they have expansion valves by the firewall. So they have thermostats in the system to measure temp of the evaporator. I have never worked on a/c on cars other than a quick charge here and there.

That is why I never wanted to work on cars. Your tech book is 40 pages. The one I had from Bendix for Mack trucks is 10-15 pages. Of course that was 15 years ago. I have done no a/c work in 10 years. So I am sure things have changed.

 

[MustangChris]

okay... i read the air conditioning section of my ford manual and i had my older brother (mechanical engineer) talk it through with me.

***the key to A/C is that it takes more energy to change a liquid to a gas****

I couldnt get all the dots to line up in my mind reading the book, so i asked my brother.... Just like when you sweat on a hot day, your sweat may be 100* and the outside air may be 120*, but it will *STILL* cool you down.

when the 100*F outside air hits the evaporator it takes more energy than just the heat out of the air to change it from the liquid to a gas. THat was the point that I couldnt get..... it took me literally 2.5 hours of studying my manual and working with my brother to get this to make sense... thanks all for all your help!!

 

[uncltrvlnmatt]

A little long winded explenation but that sums it up. You did forget about the thermostat at the evaporator. The thermostat measures the evaporator temp so that it does not turn into a block of ice. That is why you a/c compressor is always cycling or turning on and off. Also there is a high presure switch that shuts the a/c system down incase of a part failure. The most common high presure problem you will get is the small orifice getting clogged not allowing the R134a to pass through. That is usually caused by the receiver/dryer desicant getting saturated, breaking apart and going through the system.

In my expiriences with working on a/c systems the high side(Hot red gauge) presures are normally in the 180-200psi range and the low side (Cold blue gauge) is in the 60-80psi range.

It doesn't measure temp it measures pressure iirc. Your evap can turn into a block of ice if you have an issue with the amount of freon in the system for one. Most V8 systems on the 5.0 didn't cycle unless they were low on freon. The 4.6's computer controls the compressor cycling it by the pressure switch. The ones that have a temp sensor don't use an orifice, they use a valve that opens and closes by temp.
No one else took the time to explain how it works, I did, long winded or not, it's better than nothing. And long winded is the 40 pages in the auto tech book.

Just to clarify, I did not mean long winded in a bad way. I was just thinking you went to deep into the inner workings of exactly how it works. With people who have little or no expirience with a/c it could be very confusing. Sometimes the KISS method works best.

 

[NXcoupe]

okay... i read the air conditioning section of my ford manual and i had my older brother (mechanical engineer) talk it through with me.

***the key to A/C is that it takes more energy to change a liquid to a gas****

I couldnt get all the dots to line up in my mind reading the book, so i asked my brother.... Just like when you sweat on a hot day, your sweat may be 100* and the outside air may be 120*, but it will *STILL* cool you down.

when the 100*F outside air hits the evaporator it takes more energy than just the heat out of the air to change it from the liquid to a gas. THat was the point that I couldnt get..... it took me literally 2.5 hours of studying my manual and working with my brother to get this to make sense... thanks all for all your help!!

Actually, it takes both pressure change and temp to make it go from liquid to a gas, it's really simple. Dry ice is a good example, it is solid CO2, pressurized some but mostly supercooled to turn it from a gas into a liquid and then into a solid, then you set it outside, and it 'melts' into a gas. Temperature and pressure are the key factors in a/c. If you ever watch the gauges on an a/c sytem on a hot summer day, the pressures will climb in the condensor because the temps are so high that it requires a lot more pressure to turn that gas into a liquid, because of the lack of cool air coming across the condensor, you will also see the suction or low side pressures rise as well.
As long as in your mind you understand it is all that matters, if I had some diagrams and was there in person with you, it would have taken about 15 minutes for you to understand.

 

[MustangChris]

yea, the changing of the pressure raises/lowers the boiling point and condensation point, thus making the condensor and evaporator both work with the same principles behind them. air blows across the condensor to cool the R134a, same air blows across the evaporator to "heat" the R134a.

after studying and working on this, i would love to shake the hand of the man who invented the air conditioner system for cars... its litterally amazing...





**********ANYWAYS, Back to original question:**********

I am replacing my evaporator (ill be in the dash anyways, doing the heater core and the evaporator.) I replaced it with the 1996 GT unit.

from what I understand:
The dryer is the same part. (ill just buy a new one.)
THe lower dryer to compressor line is the same (ill use my old one, replace the o-rings and clean it)
The compressor is the same (use my old one.)

are the compressor to condensor lines the same? (1996 GT body 2004 Cobra Engine)
is the condensor the same?
is the condensor to evaporator lines the same?
are the evaporator to dryer lines the same?

what is this "recall" that was performed, and how do i find out if my GT had it done?

Thanks again, everyone, for all your help!