a/c expansion valve?

[Brandon8965]

ok i can't find any information on this piece of the a/c anywhere! i've looked everywhere that i know to and nothing. i do believe that its the expansion valve that is messed up but i don't exactly know where it is. everything else is brand new throughout my a/c system. but there is absolutely no cold air.. system is full of freon.... someone please help!

[loystock]

The Expansion Valve is mounted close to the Evaporator, high pressure side, with copper tube. You have to make sure the AC system is evacuated properly before working on it.

You have to verify the compressor is working. If not, the problem could be with the compressor clutch, AC Relay, Triple Pressure Switch (on top of Liquid Tank or Dryer) or the overheat switch in the compressor itself. If the compressor is engaging, then you need an AC Manifold Pressure Gauge to measure the high and low pressure side. Without the manifold gauge, it will be a guessing game and parts may be replaced needlessly.Such gauge can be rented from Autozone and the likes.

Refer to the link below so you can be more systematic in diagnosing the problem. Page HA-12 gives the layout of the AC system while pages HA-24 & 27 give diagnostic procedure for NO COOLING problem. There is also a built-in diagnostic available for your AC system.

http://www.nicoclub.com/FSM/maxima/1999/HA.pdf

[NutriaforBreakfast]

From what research i have done, I think the main thing that can go wrong with
an expansion valve is for it to be plugged up with gunk. I think it basically takes
the freon/r12 from a high pressure gas to a low pressure liquid since the opening
size of the valve and the exit side of the valve have different orifice sizes.

[loystock]

The Expansion Valve meters the amount of refrigerant going into the evaporator as a function of the evaporator discharge temperature. Too little refrigerant results to insufficient cooling while too much refrigerant causes the evaporator to freeze. The refrigerant going into the Expansion Valve is in liquid form.

The high pressure gas from the compressor is condensed (gas to liquid) at the Condenser and then filtered (w/ vapor extraction) at the Receiver-Dryer (a.k.a. Liquid Tank). At the Evaporator, cabin air heat is absorbed and dehumidified resulting into cold dry air at the discharge. Since the refrigerant (R-12 or R-134a) has low boiling point, the warm cabin air causes the refrigerant to boil (liquid to gas), enhancing the heat extraction process. The low-pressure gas is then compressed by the compressor and the cycle is repeated.

Assuming the control system is Ok, insufficient cooling can be caused by low refrigerant level, failing or inoperative compressor, defective expansion valve, contaminated refrigerant (water in the line can freeze and restrict refrigerant flow), etc.

[Markc]

AS an H.V.A.C tech, I can tell you that Loystock knows what he's talking about. That's exacly how it works and without gauges it is a guessing game.

[Brandon8965]

so if it's clogged or stopped up how do i go about reversing that.. according to the guys who were working on the car before that is what the problem was.

sorry it took so long to reply i've been hella busy with life mess

[loystock]

You have to replace it. But before that, your system must be evacuated and checked for leaks.

[crazyguy]

Not to hijack this thread, but I may be experiencing the same problem on my wife's '00 i30. The backstory is that the clutch went out on the compressor (signified by loud metal rubbing sound and melted plastic buildup between pulley and compressor). I bought a used compressor and put it on last night. I first emptied the system. I did not replace any other component....I know it's best but i'm trying to save money with kiddo number dos on the way. I get it all hooked up and add PAG oil. I began to add 134a, but stopped before emptying an entire container because the pressure was at about 65psi! it was about 85 degrees in my garage when doing this, i'm in south florida, and the car was running which would raise the ambient temperature as well. I understand that the psi is going to be higher than normal-but this seems too high, and the system does not want to take additional refrigerant. I would also prefer not blowing up my hand. This leads me to believe that I have a clogged orfice, or expansion valve. I looked at the pdf, hoping that it would be just like the i30-but it doesn't seem to be. Can someone lead me in the correct direction as to the location of the orfice/expansion valve, and a procedure that would allow me to replace it on my own. Thanks.

[loystock]

Just remember, it is illegal to discharge refrigerant into the atmosphere.

At 85F ambient air temperature, the LP side should be 31-37 psi and the HP side at 149-185 psi. It's also possible that you don't have the right amount of lubricant in the system. Unless you sealed the system after breaking the AC line, the Drier (liquid tank) has to be replaced as it gets saturated with water vapor easily.

The expansion valve is inside the evaporator housing. You have to evacuate the system and then disconnect the fittings on the firewall (going into the evaporator). Remove the glove box and other components to have access to the evaporator housing. It is a tight area to work with so you have to be patient.

Refer to the link below for additional info - page HA-84 for pressure and temperature information and diagnostics and HA-118 for component layout and installation.

http://www.nicoclub.com/FSM/i30/2001/ha.pdf

[Brandon8965]

so being that it's illegal to release the refrigerant into the atmosphere how do you go about discharging the system and such in order to replace the expansion valve.

i can't take this black leather and 106 degree weather anymore with just windows rolled down loll

[NutriaforBreakfast]

The pros use a pump to capture the refrigerant-a company called
Mastercool makes them along with a lot of other AC tools

[crazyguy]

Just remember, it is illegal to discharge refrigerant into the atmosphere.

At 85F ambient air temperature, the LP side should be 31-37 psi and the HP side at 149-185 psi. It's also possible that you don't have the right amount of lubricant in the system. Unless you sealed the system after breaking the AC line, the Drier (liquid tank) has to be replaced as it gets saturated with water vapor easily.

The expansion valve is inside the evaporator housing. You have to evacuate the system and then disconnect the fittings on the firewall (going into the evaporator). Remove the glove box and other components to have access to the evaporator housing. It is a tight area to work with so you have to be patient.

Refer to the link below for additional info - page HA-84 for pressure and temperature information and diagnostics and HA-118 for component layout and installation.

http://www.nicoclub.com/FSM/i30/2001/ha.pdf

Thanks for the diagram. The dryer is on the bottom right, correct?

[enduroexpertfsr]

you use a reclaim machine, that pulls the refrigerant out of the system, and stores it in a tank, untill you are ready for it. to crazy guy the hijacker, sounds like you never pulled a vacuum on the system before charging with refrigerant....