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If your A/C system is empty, it might be a good time to replace the O-rings at each of the plumbing flanges...or at least, the ones going to the dryer.
Note that both high & low pressure fittings are under plastic cowl below windshield, on PS.
Good move, cheap enough.
Years ago the EPA tried to regulate AC hose replacement every 4-5 years IIRC, it didn't happen. That doesn't mean you shouldn't consider it after15 years!
If your A/C system is empty, it might be a good time to replace the O-rings at each of the plumbing flanges...or at least, the ones going to the dryer.
Note that both high & low pressure fittings are under plastic cowl below windshield, on PS.
New O rings installed on all connections.
Just didn't think that the drier has to be replaced every time you open the system.
Generally it doesn't, but I gathered your system had been open for weeks which would allow the desiccant to pick up water vapor in the system.
Yes, vacuuming the system and holding it for 45 minutes will remove water vapor from the system but I don't know if it will remove water vapor from the desiccant, which is generally a chemical vapor removal. Some desiccants can be reactivated (dried) by heating above 212F, but clearly that would be difficult for an auto ac system.
For silica gel and bentonite desiccants, it's generally oven temperature 250 deg plus 5 and allow the desiccant to reach the same temperature. Activation or reactivation of both silica gel and bentonite clay can be achieved at temperatures as low as 220F. Some bags or gels will melt at around 325F so you don't want to allow radiation (IR) from the oven heat source to locally heat the bag or component above 250+5F.
I know of no procedure to reactivate the receiver/dryer component….heating to 250F in a convection oven for 24 hours might do it if you had forced air through the component and removed any elastomer seals/O-rings…or perhaps running 250F air through the receiver/dryer for 24 hours. Your AC system, your choice, but it's a lot less hassle to just put in a new receiver/dryer.
I did find one reference to a Toyota receiver dryer..not enough vacuum, even with a two stage pump. A turbo pump to remove the moisture from the desiccant. The molecular sieve desiccant will release water when the partial pressure of water vapor above the desiccant is lower than the partial pressure of moisture inside the desiccant. To reactivate the desiccant you would need to reduce the pressure to less than 10 microns for as long as it takes for the water to migrate out of the sieve (hours / days?). The recommended procedure from UOP (who makes the sieve) to regenerate the desiccant is to heat to 600 degrees F and pass dry nitrogen through the drier for four hours. If you overheat the sieve, you will destroy the crystalline structure of the sieve and ruin it.
Last edited by SloopJohnB@mac.com; 07-26-2014 at 05:02 AM.
I bled the system to reduce the pressure (70 psi).
Just back from A/C shop (wanted them to vac and fill the system).
They had vacuum on for 30 min, but could not fill the system (high pressure side climbing rapidly).
They suspect an orifice in the system got plugged up.
Recommend to replace:
Expansion block
Orifice tube
Receiver dryer
I have not tried to located the parts, part numbers, sources, etc.
Please chime in/comment:
a) Is their diagnosis correct?
b) Did they miss anything?
c) part numbers, location of the parts
d) DIY instructions to replace them
c) source to order the parts
- Cap
(A6) Audi A6/Avant
13MM.*
More Details...
- Protective cap
(A6) Audi A6/Avant
17MM.*
More Details...
- Valve safety switch high pressure switch . A/C SWITCH.
(A6) Audi A6/Avant
supply.*
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1 Receiver drier . A/C DRIER.
(A6) Audi A6/Avant
500 -501-.*
More Details...
2 Bracket for drier
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
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3 Air condtioner condenser . AIR CONDITION CONDEN. AC CONDENSER.
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
More Details...
4 Air conditioner hose (air conditioner compressor) air conditioner condenser) . REFRIGERANT HOSE. REFRIGERANT. A/C HOSE. AC HOSE.
(A6AR) Audi A6 allroad quattro
500 -401-.*
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5 (fluid container > air conditioner hose air conditioner compressor . REFRIGERANT HOSE. REFRIGERANT. A/C HOSE. AC HOSE.
(A6AR) Audi A6 allroad quattro
500 -401-.*
More Details...
6 Refrigerant tube (evaporator > water box) . REFRIGERANT PIPE. AC TUBE. AC PIPE.
(A6) Audi A6/Avant
lhd.*
More Details...
7 Refrigerant tube (air conditioner condenser > evaporator) . REFRIGERANT PIPE. AC TUBE. AC PIPE.
(A6AR) Audi A6 allroad quattro
lhd.*
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8 Double grommet
(A6) Audi A6/Avant
9,5/17,5MM.*
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9 Retaining spring air conditioner hose . REFRIGERANT HOSE. REFRIGERANT. A/C HOSE. AC HOSE.
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
More Details...
10 Air conditioner hose (fluid container > evaporator) . REFRIGERANT HOSE. REFRIGERANT. A/C HOSE. AC HOSE.
(A6) Audi A6/Avant
lhd.*
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11 Double grommet
(A6) Audi A6/Avant
lhd.*
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12 Round seal marked with:
(A4Q) Audi A4/S4/Avant quattro
10,8X1,82.*
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12 Round seal paint capacitor . CONDENSER.
(A4Q) Audi A4/S4/Avant quattro
14X1,8.*
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13 Round seal marked with:
(A4Q) Audi A4/S4/Avant quattro
10,8X1,82.*
More Details...
13 Round seal paint capacitor . CONDENSER.
(A4Q) Audi A4/S4/Avant quattro
14X1,8.*
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14 Round seal paint air conditioner . A/C UNIT. A/C. AC.
(A4Q) Audi A4/S4/Avant quattro
17,2X1,82.*
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15 Seal ring . SEALING WASHER.
(A4Q) Audi A4/S4/Avant quattro
23,8X2,4.*
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15A Round seal
(A4Q) Audi A4/S4/Avant quattro
11,1X1,8.*
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17 Charge valve
(A6) Audi A6/Avant
return.*
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17 Valve safety switch high pressure switch . A/C SWITCH.
(A6) Audi A6/Avant
supply.*
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18 Charge valve
(A6) Audi A6/Avant
return.*
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18A Cap
(A6) Audi A6/Avant
13MM.*
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18A Protective cap
(A6) Audi A6/Avant
17MM.*
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23 Safety switch air conditioner compressor . REFRIGERANT COMPRESS. AC COMPRESSOR.
(A6AR) Audi A6 allroad quattro
500 -601-.*
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23A Round seal paint marked with: only for:
(A4Q) Audi A4/S4/Avant quattro
7,6X1,8.*
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24 Restrictor valve for refrigerant:
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
More Details...
36 Capacitor bracket . CONDENSER.
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
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37 Damping rubber capacitor air condtioner condenser . AIR CONDITION CONDEN. AC CONDENSER.
(A4Q) Audi A4/S4/Avant quattro
upper.*
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38 Damping rubber capacitor . CONDENSER.
(A4Q) Audi A4/S4/Avant quattro
lower.*
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39 For vehicles with ambient bracket temperature indicator
(A6) Audi A6/Avant
front, lower.*
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41 Trim panel for hatch gate speed nut for vehicles with airbag . TRIM FOR HATCH GATE. TRIM FOR TRUNK LID. TRIM FORLIFT GATE. TRIM FOR REAR LID.
(A6) Audi A6/Avant
(9AD) Heating and air conditioning system: Climatronic, free of cfc.*
More Details...
Ordered so far:
Drier: 4B0820193A
Orifice tube/restrictor valve: 4B0820177
What is (and need to replace)?
Charge valve: 8A0820855AB
Don't need to replace unless it's leaking refrigerant…this is part of the low pressure port.
Valve safety switch high pressure switch . A/C SWITCH: 8A0820855AA
Another item you don't need to replace unless it's failed open…it should be a continuity across the terminals or to ground if only one terminal. It opens at a high pressure fault to shut off the compressor.
Generally you don't have to replace the orifice tube/restrictor valve unless it's crudded up. I don't know if there is a filter/screen ahead of this item (there is on older volvos, for example…you just replace the filter/screen).
07-25-2014, 10:37 AM
