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R56 How to replace an R56 Mini Evaporator

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Old Aug 21, 2025 | 08:57 AM
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How to replace an R56 Mini Evaporator
I am in the process of replacing my R56 Mini evaporator. It has been difficult as I did much of it in a 95F hot garage and made some mistakes that I hope will benefit you in not making them.

N.B., I used “NewTIS” which is a BMW written repair manual. It is free but NewTIS do appreciate donations. They cannot post it online and I think you can get it by contacting them and asking for access. I accessed it on my iPad while working in the car.

N.B., Some cars have a CD changer above the glove box. Mine has a CD changer sized cubby hole instead. It has a door that pops open and up when you push on it. I’ll refer to this as “Cubby/CD Changer” but I really don’t know about electrical connections to a CD changer. I am guessing that they both mount to the dash the same way.
I broke it down into the following components:
  1. ACCESSING HVAC UNIT
  2. ENGINE COMPARTMENT WORK
  3. REMOVING HVAC UNIT
  4. REINSTALLING THE HVAC UNIT
  5. CONNECTING THE FREON LINES
  6. NOTES ON REASSEMBLING THE DASH
    1. Notes on wiring harness
    2. Notes on fasteners
    3. Notes on electrical connectors

​​​​
 
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Old Aug 21, 2025 | 09:03 AM
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Here is a Google drive with pictures. I don't know if these are accessable but I'll put this out there.

https://drive.google.com/drive/folde...usp=drive_link

Peter
 
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Old Aug 21, 2025 | 09:05 AM
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ACCESSING HVAC UNIT
  1. Prepare an area to lay out items coming out of the car. By doing the factory instructions in reverse order, it is easy to reinstall things in the wrong order and by laying them out, you can avoid a lot of misery and additional disassembly/reassembly later. I wish I had done this the first time.
  2. Put car in location where it can sit for some time. Disconnect battery and place rubber sheet above the post to prevent accidental connection.
  3. Dash is in layers like fish scales (in front of one thing, behind another).
  4. Remove glove box and panel under left dash.
  5. Remove little rubber mat and center cubby stuff under windows switches.
  6. Unsnap and remove side panels next to center console.
  7. Remove four screws and center console, and unclip three electrical connectors. The little one requires a pick tool to release.
  8. Remove single screw under the decorative ‘airbag’ tab and unsnap roof pillars.
  9. Disconnect tachometer plug behind dash, remove two short M6 screws and pull tachometer out from dash.
  10. Unsnap silver dash part behind tachometer.
  11. Unclip top cover over steering column.
  12. Remove screws and bottom cover under steering column.
  13. Push screwdriver into hole at bottom of airbag and pop airbag off. Disconnect yellow airbag connector at top of steering wheel and ground at bottom (a little screwdriver helps).
  14. Disconnect electrical connectors and unbolt steering wheel.
  15. Tape rotary “clock spring” part of SZL unit to prevent rotation, disconnect rear connector, loosen bolt and unclip SZL to remove.
  16. Unscrew four big screws under steering column and lower steering column to floor.
  17. Open cubby door (or CD changer), unscrew the short lid screws, and unclip the cubby/CD changer lid.
  18. Then unsnap two small dash parts behind the cubby door.
  19. Pop off side parts and unscrew outer vents (including little silver screw at top).
  20. Use forceps to pull out two little vent pieces above and behind speedo. Then unscrew (very hard to access) screws behind Speedometer bezel. Unscrew speedometer bezel and start to pry out.
  21. Reach behind bezel and unclip hazard warning connector. Remove bezel.
  22. Remove screw above speedo and four in front and pull speedo and radio head unit out slightly.
  23. Reach behind speedometer and unplug it. Reach behind radio and unclip giant lever action plug and three coax plug connectors. Pull out speedometer/radio.
  24. Remove upper and lower screws and pull off central trim. On trim with key/start/stop, unplug before removing.
  25. With the central trim off, unscrew dash cubby/CD changer and pull out.
  26. Unplug passenger side airbag to right of cubby/CD changer hole in dash. Reach into cubby hole and unbolt two big bolts fastening airbags to metal frame.
  27. Pop up solar sensor at center of dash and unplug.
  28. Unscrew dash cover and pull out slightly.
  29. Reach under dash and fish solar sensor wire down and out of dash hole.
  30. Lift out heavy dash cover. Be sensitive to airbag on right side.
  31. Unscrew the plastic central support frame and pull out.
  32. Unscrew the long wide plastic support frame and pull off.
  33. Unplug big and little plugs on CAS unit behind steering wheel. Unscrew CAS and remove.
  34. Unbolt large plastic frame under dash and remove.
  35. Unbolt the armrest, gear shift stuff, hand brake, etc. and pull away from the center console. This is to access the L brackets that tie the big central metal dash frame to the floorboard.
 
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Old Aug 21, 2025 | 09:06 AM
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ENGINE COMPARTMENT WORK
  1. Raise car off the ground and remove RF tire.
  2. Remove RF fender liner.
  3. I used a 1-1/4” box end wrench to release tension on the serpentine belt and locked it in place at the tensioner.
  4. I pulled the tab and released tension on the water pump roller.
  5. Remove the serpentine belt.
  6. Drain coolant.
  7. Remove air intake filter box and hose.
  8. Disconnect water hoses below expansion valve. They use a clip and O-rings so although a bit tricky, this doesn’t require hose clamps.
  9. If you didn’t drain the coolant, expect a large wet mess when you disconnect hoses as the coolant will hit the K member and splash everywhere.
  10. Apply air pressure and blow coolant out of heater core to drain it (more mess).
  11. Release freon from AC system.
  12. Unscrew freon lines from expansion valve. Cap them if possible.
  13. Assuming you will drain and add the correct amount of compressor oil, disconnect compressor freon lines, unbolt and remove it. Cap hoses if possible.
  14. With compressor on bench, turn it over and drain the oil. There was a drain plug on the side of mine. BMW doesn’t want you add a full load as they think there will be a certain amount in the evaporator, lines, and condenser. They give a very complicated instruction on how much to add. Not much is in the lines and since they are so cheap at ~$50, and have the drier (desiccant), I replaced the condenser and evaporator and therefore added the full load of 130ml PAG46.
  15. Assuming you will replace the condenser, disconnect its freon lines, unbolt it and remove it. Cap hoses if possible.
  16. O-Rings are a pain. I bought several sets of green ones at Rock Auto and none fit so I took the purple ones I removed to the dealer and matched them up. I got extras as I didn’t want another delay because of O-rings. These BMW/Mini O-rings were also purple??? I’ve never seen that.
 
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Old Aug 21, 2025 | 09:06 AM
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REMOVING HVAC UNIT
  1. With the coolant and freon hoses disconnected from the expansion valve, unscrew the four large bolts that hold on the large metal sub dash board.
  2. Unscrew the bolts that hold the large metal sub dash to the HVAC unit.
  3. Lift out the late metal sub dash board.
  4. Unplug the connector on the HVAC unit and lift it out.
  5. Remove the evaporator on a bench.
  6. Disassemble the HVAC unit on a bench and remove the evaporator.
  7. Install the new evaporator and reassemble the HVAC unit and using new O-Rings, the expansion valve.
 
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Old Aug 21, 2025 | 09:07 AM
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REINSTALLING THE HVAC UNIT
  1. Apply some PAG oil to help act as a seal for the condensate drain on the center console carpeting.
  2. Carefully set the HVAC unit in place. Reconnect the plug. Check the alignment of the expansion valve in the firewall.
  3. Check that the drain and the rubber seal align.
  4. Lift the metal sub dash into place and attach the four giant bolts at the outer ends.
  5. Align the HVAC unit and screw in the bolts to the HVAC unit. If these go into plastic, they would have threads like a wood screw.
  6. From the engine compartment, install new freon O-rings and reassemble the expansion valve hoses.
  7. Attach the coolant lines below the Freon lines. They should click into place with a satisfying ‘click’. Tug on them to assure they attached correctly.
 
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Old Aug 21, 2025 | 09:09 AM
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CONNECTING THE FREON LINES
  1. TO AVOID DIRT AND HUMIDITY IN THE FREON LINES, I DID THE FOLLOWING IN ONE GO WITH NO OVERNIGHT DELAYS.
  2. With the freon lines attached to the expansion valve, and being careful to keep dirt out of the freon connections, install the compressor.
  3. Install new O-rings and bolt in the freon lines to the compressor.
  4. Detach the freon lines to the condenser and remove it.
  5. Install new O-rings and attach hoses to the condenser.
  6. THE FREON SYSTEM SHOULD NOW BE SEALED UP.
  7. I attached the gages and drew a vacuum and left it for some time.
 
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Old Aug 21, 2025 | 09:10 AM
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NOTES ON REASSEMBLING THE DASH
  1. Going in reverse order, reassemble the dash.
  2. I found THE MOST DIFFICULT SCREWS to attach were the two in the upper dash grill that go down from above, through the speedometer bezel flange, and into the plastic nuts on the central plastic frame. To do these, I taped the screws to the T-20 drive, and used a combination of flashlight and mirror to guide them in. I actually got pretty good after doing it five times.
  3. The four big bolts that hold the steering column should be torqued to the bottom of the large metal sub dash. These are hard to start as the threads are coarse and you have to lay under the dash and support the heavy steering column while you try to start the threads. Because the threads are kind of coarse, I think one of mine cross threaded and I broke it off while torquing. (Upside down), I drilled it out and tapped it to a normal metric thread and then tightened that new bolt with a big ratchet wrench to what felt like the proper torque.
  4. The SZL unit, (the steering column stalks, ‘clockspring’, airbag connectors) there is a note that if the tape falls off and you lose angular position, just wind clockwise and counter clockwise and return it to half way between the two. I decided to do this and it ended up 180 degrees off. Worse off, something went wrong internally and it would no longer read positive steering angles. I had to purchase another one. I to a used one off eBay and it worked just fine.
Notes on wiring harness
  1. When reinstalling the plastic central support frame, watch out for the wiring harness. In particular, you very much don’t want to crimp or harm any twisted Can Bus wires.
Notes on fasteners
  1. 10% of fasteners are a non-standard coarse M6 flange head screw with a T-30 drive. These are used to attach the plastic dash support frame to the large metal sub dash.
  2. 80% of screws are small black flange head sheet metal screws with T-20 drive. These are used to attach the dash bits to the sheet metal ‘nutserts’ in the plastic dashboard support frame.
  3. N.B., 10% of the fasteners are an odd ball variety. Keep an eye out for these as they can look very similar to the others. One key difference is the threads. If they go into plastic nuts, they would have a very wood screw type thread. Some are shiny silver. One trick I tried was to reattach the odd screws loosely after the part was removed.
  4. N.B., It was 97F in my garage and I was tired and missed many and had a dozen leftovers. I took everything apart several times to resolve this.
Notes on electrical connectors
  1. You cannot be too careful with electrical connectors.
  2. A pick or pry tool is a valuable way to disconnect the tiny electrical connectors.
  3. The easiest connectors to disconnect are the giant gear drive lever action connectors.
  4. The same gear drive connectors are also the easiest to get wrong on reattachment. After installing, tug and pry on them to make sure they are attached correctly.
 
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Old Aug 21, 2025 | 04:37 PM
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Your thread will greatly benefit members who are ambitious enough to replace a Mini Cooper evaporator.
 
Last edited by Maybe, maybe not; Aug 22, 2025 at 05:47 PM.
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Old Aug 21, 2025 | 04:41 PM
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Originally Posted by ptkacik
Here is a Google drive with pictures. I don't know if these are accessable but I'll put this out there.
https://drive.google.com/drive/folde...usp=drive_link
Peter
Photo access requested.
 
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Old Aug 22, 2025 | 10:53 AM
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Thank you, Peter! Your pictures are awesome and the best Mini Cooper evaporator replacement pictures available on the internet, in my opinion.

Below I tried to label your 126 pictures so that members can understand the content.
Some pictures (?) I wasn't sure about. Please feel free to make any corrections you deem necessary.
IMG_5439 engine bay.JPG
IMG_5440 high pressure a/c port.JPG
IMG_5442 a/c refrigerant hood label.jpg
IMG_5449 driver airbag.JPG
IMG_5450 driver airbag.JPG
IMG_5451 driver airbag-removal.JPG
IMG_5452 steering column clock spring.JPG
IMG_5453 ? connector.JPG
IMG_5454 start-stop ignition switch.JPG
IMG_5455 start-stop ignition switch.JPG
IMG_5456 start-stop ignition switch.JPG
IMG_5457 start-stop ignition switch.JPG
IMG_5458 start-stop ignition switch.JPG
IMG_5459 start-stop ignition switch.JPG
IMG_5460 center console connection to dashboard carrier.JPG
IMG_5461 heating and a/c housing-interior.jpg
IMG_5462 heating and a/c housing-interior.JPG
IMG_5463 heating and a/c housing-interior.JPG
IMG_5464 expansion valve-engine bay.JPG
IMG_5465 expansion valve-interior.JPG
IMG_5466 expansion valve-interior.JPG
IMG_5467 heating and a/c housing-removed.JPG
IMG_5468 evaporator-housing removed.JPG
IMG_5469 expansion valve & heater pipes-housing removed.JPG
IMG_5470 expansion valve & heater pipes-housing removed.JPG
IMG_5471 heating and a/c housing-removed.JPG
IMG_5472 expansion valve low & high pressure lines-engine bay.JPG
IMG_5473 expansion valve low & high pressure lines-interior.JPG
IMG_5474 expansion valve low & high pressure lines-interior.JPG
IMG_5475 parking brake handle.JPG
IMG_5476 heating and a/c housing-interior.JPG
IMG_5477 heating and a/c housing-interior.JPG
IMG_5478 dashboard carrier-interior.JPG
IMG_5479 expansion valve-engine bay.JPG
IMG_5480 expansion valve & heater hoses-engine bay.JPG
IMG_5481 expansion valve-engine bay.JPG
IMG_5482 air intake tube.JPG
IMG_5483 air intake system.JPG
IMG_5484 maintenance notes.JPG
IMG_5485 air intake MAF sensor.JPG
IMG_5486 dashboard carrier connection to center console.JPG
IMG_5487 dashboard carrier & bolt.JPG
IMG_5488 dashboard carrier-broken bolt.JPG
IMG_5489 steering column & dashboard carrier.JPG
IMG_5490 dashboard top.JPG
IMG_5491 dashboard.JPG
IMG_5493 dashboard, center.JPG
IMG_5494 upper instrument cluster & CD player.JPG
IMG_5495 upper instrument cluster & CD player.JPG
IMG_5496 ? steering column switch cluster connector.JPG
IMG_5497 tip to reach deep center vent screws.JPG
IMG_5503 managing fasteners.JPG
IMG_5504 Left lower dashboard trim.JPG
IMG_5505 left side center dashboard cover.JPG
IMG_5506 tachometer.JPG
IMG_5507 tachometer.JPG
IMG_5508 ? left dashboard knee pad.JPG
IMG_5509 left dashboard trim.JPG
IMG_5510 left dashboard trim.JPG
IMG_5511 right dashboard trim.JPG
IMG_5512 storage compartment right trim.JPG
IMG_5513 storage compartment right trim.JPG
IMG_5514 storage compartment lid.JPG
IMG_5515 storage compartment lid.JPG
IMG_5516 storage compartment lid.JPG
IMG_5517 storage compartment lid.JPG
IMG_5518 storage compartment lid.JPG
IMG_5519 storage compartment lid.JPG
IMG_5520 instrument bezel mounting screws.JPG
IMG_5521 instrument bezel mounting screws.JPG
IMG_5522 instrument bezel mounting screws.JPG
IMG_5523 instrument bezel.JPG
IMG_5524 lower center dashboard cover.JPG
IMG_5525 lower center dashboard cover.JPG
IMG_5526 lower center dashboard cover.JPG
IMG_5527 dashboard bezel.JPG
IMG_5528 dashboard bezel.JPG
IMG_5529 dashboard bezel.JPG
IMG_5530 dashboard bezel.JPG
IMG_5532 left dashboard end cover.JPG
IMG_5533 door and window seal.JPG
IMG_5534 right A pillar.JPG
IMG_5535 door and window seal.JPG
IMG_5536 right A pillar.JPG
IMG_5537 right A pillar.JPG
IMG_5538 right dashboard end cover.JPG
IMG_5539 right dashboard end cover.JPG
IMG_5540 vent mounting screws.JPG
IMG_5541 vent mounting screws.JPG
IMG_5542 vent mounting screws.JPG
IMG_5543 passenger knee pad.JPG
IMG_5544 driver knee pad, left.JPG
IMG_5545 start-stop ignition switch.JPG
IMG_5546 start-stop ignition switch.JPG
IMG_5547 start-stop ignition switch.JPG
IMG_5548 start-stop ignition switch.JPG
IMG_5549 ? connector.JPG
IMG_5550 ? CD player connectors.JPG
IMG_5551 ? .JPG
IMG_5552 center instrument panel-dismantled.JPG
IMG_5553 lower center instrument panel & center console.JPG
IMG_5554 dashboard & cover.JPG
IMG_5555 dashboard & cover.JPG
IMG_5556 dashboard & cover.JPG
IMG_5557 dashboard & cover.JPG
IMG_5558 dashboard & cover.JPG
IMG_5559 center console.JPG
IMG_5560 center console.JPG
IMG_5561 center console.JPG
IMG_5562 upper steering column cover.JPG
IMG_5563 driver airbag-removal.JPG
IMG_5564 driver airbag-removal.JPG
IMG_5565 driver airbag-removal.JPG
IMG_5566 driver airbag-removal.JPG
IMG_5567 steering wheel.JPG
IMG_5568 steering column clock spring.JPG
IMG_5569 steering column switch cluster.JPG
IMG_5570 steering column switch cluster.JPG
IMG_5571 steering column switch cluster.JPG
IMG_5572 dashboard carrier.jpg
IMG_5573 organized removed parts.jpg
IMG_5574 intact dash.JPG
IMG_5575 intact dash.jpg
IMG_5576 bolts & screws.jpg
IMG_5578 Sanden SD6V12 variable displacement compressor.JPG
IMG_5579 Sanden compressor o-rings.JPG
 
Last edited by Maybe, maybe not; Aug 24, 2025 at 08:43 AM.
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Old Aug 23, 2025 | 02:22 PM
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This fantastic video clearly details the step-by-step procedure for removal of the R56 dashboard.
The video shows a RHD R56, but the details are the same for a LHD R56.

 
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Old Aug 24, 2025 | 09:11 AM
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Originally Posted by ptkacik
ENGINE COMPARTMENT WORK
With compressor on bench, turn it over and drain the oil. There was a drain plug on the side of mine. BMW doesn’t want you add a full load as they think there will be a certain amount in the evaporator, lines, and condenser. They give a very complicated instruction on how much to add. Not much is in the lines and since they are so cheap at ~$50, and have the drier (desiccant), I replaced the condenser and evaporator and therefore added the full load of 130ml PAG46.
Please correct me if I'm wrong: You replaced the evaporator, condenser and drier. You did not replace the compressor, expansion valve, or any refrigerant lines.

Did you flush old oil from the old components that you re-used? If so, how did you do it?

Also, did the dealer parts department verify that 130 ml of PAG46 was the correct starting volume for the A/C system devoid of oil?

O-Rings are a pain...so I took the purple ones I removed to the dealer and matched them up. I got extras as I didn’t want another delay because of O-rings.
Did the dealer sell OEM O-rings as a total A/C system kit or only individually?

 
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Old Aug 24, 2025 | 09:26 AM
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I did replace the evaporator, condenser and drier (which is in the new condenser). I did not replace the compressor, expansion valve, or any refrigerant lines.

Flushing is more valuable when the compressor fails and dumps grit into the lines or if the lines stay open for a long period of time. I purchased a flushing system and flushing fluid but since there was so little time with it disconnected and so much replaced, I didn’t flush it. I’ve done it the past when I changed from R12 freon to R134a.

Dealer was not very knowledgeable. They could only match O-rings to what I had. Their freon lines in the part catalogue didn’t even match what was in my car. Their lines might have worked but they were different. They seemed to have no clue about PAG oil volume.

The first O-rings from the Rock Auto kit seemed to fit the Expansion valve okay but the compressor O-rings didn’t fit all. That’s when I went to the dealer. I still worry about the expansion valve O-rings but they are pretty easy to replace (except for all of the freon).

The car now runs fine, the A/C is cold, and there are no check engine lights; however, my scanner still says there is a D904 CAS: K-Can line fault.

Peter
 
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Old Aug 24, 2025 | 09:30 AM
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Thanks, Peter. That's very helpful information.

What method did you use to recharge the A/C system with the correct R134a weight?

Is D904 ever occasionally accompanied by any other (pending or historical) K-CAN codes? Mine had several pending/historical fault codes, one of which was TPMS module K-CAN code D104. That's what prompted me to check the TPMS module K-CAN wires.
 
Last edited by Maybe, maybe not; Aug 24, 2025 at 09:47 AM.
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Old Aug 24, 2025 | 09:54 AM
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Sadly, I only get one fault; “D904: CAS, K-Can line fault” so I’m shooting in the dark using where the fault might be located. I’ve taken the dash apart five times at least and not found anything.

I’ve made a mess several times while working with freon so ended up writing out how to avoid the mess and excessive loss of freon. I tried to get the correct freon by watching the pressures but added way too much. I discharged the freon and charged a second time. This time, I sat the Freon bottles on a digital kitchen scale and weighed out the amount. The first bottle didn’t drop enough in weight so I added a second bottle. I matched the total added freon to the label under the hood. As I recall, it said something like 1.02 pounds +/-0.04 pounds.

Method for repairing something in the freon system
  1. Engine off.
  2. Close gage valves.
  3. Attach freon gages to hoses and then to high and low pressure taps.
  4. Open up hoses valves and record high and low side pressures.
  5. Place charge hose in bucket to catch oil residue.
  6. Open up low pressure valve.
  7. Crack charge hose and bleed pressure off slowly into bucket.
  8. Relieve pressures to zero.
  9. Now components have no pressure on them and can be disassembled.
  10. Use new O-Rings when reassembling components.
  11. N.B., the dealer sells purple O-Rings, not green ones.
  12. If system is open for over 24 hours, you must replace the drier desiccant on the condenser.
  13. Connect up vacuum pump and run for at least 45 minutes.
Method for charging evacuated system
  1. N.B., the correct amount of freon is written on a sticker under the hood. Too little or too much will adversely affect the cooling ability of the system. It is advised to put in the exact amount recommended. My 2013 Mini said 460g of R134a freon (1.01 +/- 0.02 lbs).
  2. Hold vacuum for at least 30 minutes without losing and vacuum.
  3. Close all valves on gages.
  4. Attach new Freon can to charge hose.
  5. Turn on charge hose faucet valve, pressurizing hose.
  6. Bleed charge hose at gages. Open slightly and let hiss for a few seconds then seal hose.
  7. Set up scale and weigh hose and freon can. Write this number down.
  8. There will probably be 326g freon in a can.
  9. If you want more than 326g, then prepare to empty the can.
  10. Start car and set A/C to max cooling.
  11. All gage valves should be closed.
  12. Open blue low pressure valve.
  13. Crack open charge hose valve and start to bleed freon into system through low pressure side only.
  14. Charge system with inverted can (hose and top down).
  15. Monitor weight repeatedly until the can weighs the correct amount.
  16. When you reach the correct weight of freon, close charge and low pressure valves.
  17. Record:
    1. High side pressure
    2. Low side pressure
    3. Ambient temperature
    4. With my freon exactly right, I measured lower than typical numbers.
    5. 31psi low, 215psi high, at 78F
Method for releasing freon pressure (without making a mess)
  1. Turn off hose ***** at pressure taps first.
  2. Release pressure in gages through filler hose.
  3. Disconnect all hoses and put away.
 
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Old Aug 24, 2025 | 10:18 AM
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Your excellent thread should be helpful to many members!

Does your code reader display pending or historical fault codes?

In the absence of one or more pending/historical K-CAN codes, the recommended approach is to unplug control modules (they connectors with twisted pair of K-CAN wires) one-by-one in the engine bay and behind the dash to see whether one unplugged control module eliminates code D904.
 
Last edited by Maybe, maybe not; Aug 24, 2025 at 10:29 AM.
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Old Aug 24, 2025 | 10:50 AM
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To look for any more fault codes I took it out and drove it around up and down the highway and came back and there is one more. RDC: K-can line fault which is the TPMS RDC system.

I find the odd as the TPS system starts at the foot well module and goes to the back of the car
 
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Old Aug 24, 2025 | 10:54 AM
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Since it doesn't cause any driving issues and no check engine light, it is possible the code was there before I started on the AC.

The RDC module is in the rear bumper. Do you think I ought to disconnect it and look for a fault change?
 
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Old Aug 24, 2025 | 10:56 AM
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Originally Posted by ptkacik
To look for any more fault codes I took it out and drove it around up and down the highway and came back and there is one more. RDC: K-can line fault which is the TPMS RDC system.

I find the odd as the TPS system starts at the foot well module and goes to the back of the car
Haha...I agree that it's unexpected. But it may warrant removing the rear bumper cover to see whether unplugging the RDC/TPMS module eliminates D904.
 
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Old Aug 24, 2025 | 10:59 AM
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Originally Posted by ptkacik
Since it doesn't cause any driving issues and no check engine light, it is possible the code was there before I started on the AC.
It's plausible.

The RDC module is in the rear bumper. Do you think I ought to disconnect it and look for a fault change?
​​​​​​​Yes!
 
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Old Aug 24, 2025 | 11:00 AM
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I was curious to know more details about your evaporator leak.

By what method did to you pinpoint the leak to the evaporator?

Did your evaporator have a slow leak or a large leak that emptied the system quickly?

I saw what may have been signs a large amount of PAG oil on the old evaporator. Or was the staining something else?
 
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Old Aug 24, 2025 | 11:26 AM
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The leak took two months to drain down and start giving poor performance.

I put UV die Freon in and use the UV light but found nothing.

I used to TIFF Freon detector and only got a signal when I had the detector sniffing down one of the air vents.

The evaporator was dirty and dusty, even some leaves,but really didn’t have any signs of Freon or oil on it
 
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Old Aug 24, 2025 | 11:29 AM
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My leak reduces cooling about 8 months after a R134a top-off. My $20 cheap electronic refrigerant detector finds what seems to be a large refrigerant signal in the passenger footwell, but I think the detector is extremely sensitive.
 
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Old Aug 24, 2025 | 01:10 PM
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I took the rear bumper off last year looking for a cut in the RDC wires. I didn’t find anything.

Ha! I need to look at my notes and see if I had those K-Can line faults back then.

Peter
 
Last edited by ptkacik; Aug 24, 2025 at 02:20 PM. Reason: Duplicate thread
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