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  1. #1
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    AC Compressor and expansion valve

    I need to replace the AC compressor and expansion valve and dryer in my 2004 EP. Do I need to do anything special other than evacuate the freon from the system prior to removing the hoses and parts? I plan to install the new compressor, expansion valve and dryer the day before the system is recharged. Also, is there a way to remove the expansion valve other than removing the heater core unit under the dash? Is the compressor oil added with the freon together when the system is charged or do I need to do something else with that? Thanks

  2. #2
    turbo+386whp+298wtq ep3k20's Avatar
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    the "freon" is actually the brand name given from dupont it is actually just called refrigerant. the refrigerant is actually THE oil in which lubricates the compressor. Look at it this way, when our cars are low on oil the lifters start to tick a bit, by adding oil they quite down. You ever been into a store and a chiller box (for like soda or something) is really loud making obnoxious noise? same basis, it is low on refrigerant. You really just need a gauge set up when evacuating the old system, as well as to read the pressure variables when charging. Make sure you take into account fluctuations in super heat, which is the drawn down pressure of the refrigerant in its liquid form when at max op temp. If you don't know how to read pressures or super heat pm me and i will go thru it with you. Make sure you dont over charge the system as this will flood the compressor and the evap coil and dryer will be overwhelmed and you will seize shit up fast....goes without saying but dont under charge either lol Biggest piece of advice, replace ANY o-rings from the system from the schrader valves. these dry rot fast, and can actually make the system leak relatively fast

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    Quote Originally Posted by ep3k20 View Post
    the "freon" is actually the brand name given from dupont it is actually just called refrigerant. the refrigerant is actually THE oil in which lubricates the compressor. Look at it this way, when our cars are low on oil the lifters start to tick a bit, by adding oil they quite down. You ever been into a store and a chiller box (for like soda or something) is really loud making obnoxious noise? same basis, it is low on refrigerant. You really just need a gauge set up when evacuating the old system, as well as to read the pressure variables when charging. Make sure you take into account fluctuations in super heat, which is the drawn down pressure of the refrigerant in its liquid form when at max op temp. If you don't know how to read pressures or super heat pm me and i will go thru it with you. Make sure you dont over charge the system as this will flood the compressor and the evap coil and dryer will be overwhelmed and you will seize shit up fast....goes without saying but dont under charge either lol Biggest piece of advice, replace ANY o-rings from the system from the schrader valves. these dry rot fast, and can actually make the system leak relatively fast
    I am taking it to a shop to get the gas evacuated and recharged with right amount, my mechanic has a machine that he programs with the right amount of gas. My question was more concerning the compressor itself as I install the new one I hear I have to put oil in it as well as in the new dryer unit, I do not know how much oil I have to pour into either component prior to installation. I also needed to know if the only way to remove the expansion valve is by removing the core and evaporator from under the dash. Thanks

  4. #4
    turbo+386whp+298wtq ep3k20's Avatar
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    honestly dont know what amount of "oil" is to be used. as for the core and evap coil they are in the dash as one unit and as far as i am concerned a bit of a PIA to remove. and is rather messy as well since your heater core is directly correlated in conjunction with one another which means you will be dealing with coolant. Obviously you will need to drain your coolant in order to remove said parts. Unfortunately i have had to deal with such problems on other a/c cars and theyre all F'ING PIA lol

  5. #5
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    Would be great to have a sticky with the entire procedure from beginning to end. I do not know much about AC systems. Looks to me it can be tricky. For instance, I heard you have to flush the lines with a chemical to clean them before installing the new compressor and receiver, and expansion valve. Then I hear some compressors are shipped with oil and others come dry. I am trying to figure this out so I can do most of the work myself and not have to wait for a couple of days to get the car back, and save some major $$ in labor. I thought it would be ok to swap the compressors and dryer units and go recharge the system but it seems there is more to it...what a PITA.

  6. #6
    turbo+386whp+298wtq ep3k20's Avatar
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    Quote Originally Posted by EP3driver View Post
    Would be great to have a sticky with the entire procedure from beginning to end. I do not know much about AC systems. Looks to me it can be tricky. For instance, I heard you have to flush the lines with a chemical to clean them before installing the new compressor and receiver, and expansion valve. Then I hear some compressors are shipped with oil and others come dry. I am trying to figure this out so I can do most of the work myself and not have to wait for a couple of days to get the car back, and save some major $$ in labor. I thought it would be ok to swap the compressors and dryer units and go recharge the system but it seems there is more to it...what a PITA.
    Honestly its really not "that" difficult to evac and charge an a/c system... even repairs aren't necessarily hard either... but if you have never dealt with either then yes it will suck balls. I have actually thought about making a thread on DIY of repair and recharge of an a/c system because from what i can tell, there is no threads of the sort like this at all. Too bad i was not in texas or i would use your car as my guinea pig lol. The chemical you are referring to to clean the system is ONLY required when adding a different type of refrigerant to a system ie; r-22 changing over to r-134, but this is a feat in itself because different refrigerants use different rubber compounds for the sealant part. Different refrigerants break different rubbers down. You have to flush every single bit out as this will cause the evap coil to clog on the low suction side and cause system failure within minutes. It's like a blood transfusion, you have to use same for same. The oil that they put in the compressors is basically like an anti-seize that coats the "piston" within the compressor because moisture in the air WILL lock that piston shut with rust, so they all come with some sort of lubricant as a safe gaurd

  7. #7
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    how do you even get to the compressor,

  8. #8
    無限SKOOGEN skoo74's Avatar
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    how much was the compressor... mine just shitted this weekend.. I haven't had a chance to look at it but it exploded while driving on the freeway.. just saw saw smoke and parts flying from the rear... crap

  9. #9
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    to get to the compressor you remove the bumper, remove the head light, pull out the coolant over flow, and the radiator fan, then pull out the alternator and there is the compressor, do not get the denso compressor that advance auto and amazon both show as a good part 471-7051 it is not a good number for the si it is the number that the denso site lists for the 1.7 engine not the 2.0. its a little bit of a pain in the a$$ but rock auto has all 3 parts for right around 300 bucks.

  10. #10
    無限SKOOGEN skoo74's Avatar
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    good stuff geeio... i just bought that exact denso compressor... i'll probably return it tomorrow then.. which one did you end up getting?

  11. #11
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    dang I just bought expansion valve, I swapped out my ac compressor 2 weeks ago, not sure what to really do. this Texas heat sucks!

  12. #12
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    Im having problems with mine on my 03 Si.. So the expansion valve is behind the dash..?

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