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AC System Teardown & Rebuild

518 Views 11 Replies 4 Participants Last post by  Rez
After 18 years and 94k miles, the factory AC system has died. Living in Houston, TX this is unacceptable, so I did a complete teardown, replacement and refurb of the AC system. This post is to show pictures, tips and lessons I learned during this process.

The car is a 2006 Magnum srt8 that I have owned since 2009. I purchased the car with 30k miles and it was my daily driver from 2009-2014. It sat in storage untouched from 2015-2018, and I have driven only 1-2k miles per year since 2018. It is now a weekend cruiser and easing into retirement.

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I first noticed the AC problem when I could smell refrigerant gas coming out of the air vents – a sign of a leaking evap core. A few months later, the smell was still there and the AC wasn’t cooling at all. Time for a teardown. I quickly concluded that the dash needed to be completely removed to access the evap core. This is not the case for the heater core, however which can be accessed by dropping the steering column.

The main mistake I made was removing the dash cover first, and the dash sub-frame separately. It would have been much better to remove the whole frame/cover assembly as one piece. There are only 10 bolts that hold this assembly in place as shown below – 3 on each side, 2 at the top by the windshield, and 2 at the bottom by the center console.

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There are two reasons why it’s better to remove the dash frame/cover together as one assembly. Firstly, there are so many small fasteners between the cover and the frame which are difficult to see and difficult to access. The second reason is the hvac ducting which lies between the frame and the cover as shown below. These ducts are screwed to BOTH the frame and the cover. If you remove only the cover first, you will have to cut and re-epoxy the mounting tabs for the air ducts. Those screws are impossible to access while the dash frame is still in the car.

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Here is another view showing the drivers side HVAC duct under the dash cover. You can see the screws that hold it to both the dash cover and the dash sub-frame.

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Bottom line – remove the dash frame/cover assembly as one piece and you’ll avoid a lot of hassle.

There are several electrical connectors on both sides that need to be disconnected, in addition to the removal of the center console, gauge cluster, A-pillar covers, and steering column before you can remove the dash. You also need to disconnect the steering tilt/telescope linkage, hood release, parking brake cable, ignition lockout cable to the shifter mechanism, and remove the glove box assembly.

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The steering column is a little tricky, there are 3 bolts that secure the column to the dash subframe.

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Once you get everything disconnected, get a friend to help you remove the entire dash frame/cover assembly as one piece. I built a simple wood mount for the dash, then covered it in painters plastic to protect it from the elements and humidity in my garage.

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...continued on the next post...
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Once you get the dash assembly removed, the HVAC air box is exposed and can be removed. The below photo shows after the box is removed, there are 5 mounting points. The top two points are 10mm nuts that are accessed from inside the car. The bottom 3 are 10mm nuts that are accessed from the engine bay. The bottom right nut is behind the cabin air filter intake assembly. This assembly must be removed from inside the hood area to access this nut.

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Here is a view of that bottom right nut location after the cabin air filter intake assembly is removed.

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Here is a view of the HVAC box out of the car, upside down. You can see the PAG oil residue at the condensation drain port for the evap core. This is evidence that the oil and refrigerant drained out slowly over time from the evap core.

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Here is the HVAC box split open. There are tons of little screws that hold it together, and you also need to remove the expansion valve from the evap core inlet.

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Now onto the rebuilding phase of the project. My plan was to replace all of the main AC system components, all seals, and all poppet/Schrader valves. I intend to have this car forever and I want the AC system to last at least another 18 years.

I opted to replace the compressor because it was completely empty of PAG oil. My theory is that all the PAG oil leaked out through the hole in the evap core, and the compressor was running for some time perhaps with little or no oil. I managed to find the OEM Denso “Made in Japan” compressor on Rockauto for cheap.

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I also chose to replace the AC condenser, for two reasons. Firstly, the drier assembly is integral to the condenser and does not appear to be separately replaceable. Secondly, my condenser was packed with small gravel and road debris, likely reducing its cooling capacity. Also, I found the Denso unit on Rockauto, so it was a no-brainer. You can see the close-up below of the condenser.

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In parallel with the AC system, there are a few heater system items that could/should be replaced at this same time. I ordered new heater hose assemblies from Rockauto, to replace the 18-year old hoses on the car. I trashed those terrible spring clamps, and bought some new stainless steel screw-drive hose clamps. I opted to leave the factory heater core in-place, and not replace it. I couldn’t find an OEM heater core (only cheap knock-off brands) and I don’t have any reason to believe it needs to be replaced.

While everything was disassembled, I took the time to repair broken plastic tabs and deteriorated foam. I used plastic epoxy and metal ribbon to make new mounting tabs. I also used new weatherstripping seal for the foam seals around the vents, as shown below.

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Here is the parts list that I ordered for the re-assembly of the system:
  • New AC evap core, Mopar P/N: 05061585AA
  • New AC compressor, Denso P/N: 4710810. 180ml of PAG oil added with dye.
  • New AC condenser, Denso P/N: 4770829. New dryer included.
  • New AC Schrader valves installed, FOUR SEASONS P/N: 26779.
  • All AC o-rings and metal flange gaskets replaced, GPD P/N: 1321312.
  • New heater hose assemblies installed, Gates P/N: 24364 & 24365. New worm-drive hose clamps installed.
  • New heater core o-ring seals, Mopar P/N: 68239586A
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As mentioned above, I opted for an OEM Mopar evaporator core replacement (05061585AA). This was much more expensive than an aftermarket unit, however I wanted the best possible option so I don’t have to repeat this project for another 18 years. Now, is the OEM unit really any better or more reliable than an aftermarket one? I honestly don’t know. Here is a photo of the new and old. The new one from Mopar comes with the new expansion valve, seals, and foam insulation.

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Re-assembling the HVAC box with the evap & heater cores took a little time and was a little tricky to get everything back in the right place. Before taking the box apart – I highly recommend taking multiple photos of the box from all angles. Days or weeks later when you’re putting it back together, those photos are valuable to get all the harnesses, clips, and actuators back on correctly. As shown below there is one blend door actuator that needs to be removed to get the heater core in/out. This actuator has a somewhat complicated linkage mechanism that is difficult to get back together correctly.

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After the hvac box was re-assembled, I began the process to carefully put the car back together. I had a friend help me re-install the dash assembly and it went smoothly. There are lots of connectors and clips, just go slow and pay attention. Here is a picture of that wood frame with the dimensions, in case anyone wants to build one. I used some old 2x4’s and 3” wood screws.

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I finally got everything put back together and it was time to charge the AC system. Stores like AutoZone or O’Reilly’s have “free” tool rental programs for things like the vacuum pump and gauge set. I ended up buying both of these items at Harbor Freight, I got tired of the rental tools pretty much always being damaged or missing parts. The system held a vacuum perfectly, so it was time to charge.

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The spec weight for R-134a is 26-oz. I found a 14-oz and 12-oz bottle at Walmart, 14+12=26. I used a fruit scale to verify the weight of the cans before and after filling. Both were spot-on. On a previous project, I used a can labeled 12-oz however it only had 10-oz fluid inside – not good!

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Now it was time to start the engine and begin filling the freon into the AC system. The startup was successful, there were no warning lights or issues. It looks like I put everything back together correctly. Filling the freon took about an hour total. The system did not take the freon quickly, however it did eventually take the full 26-oz.

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It was 95-deg in the garage, I was able to get the dash vent temperature down to 75-deg after filling the freon. There was also a large puddle of water condensation under the car, so that was a good sign of a properly functioning AC system. The next day, I took the car for a freeway cruise and measured the vent temperature at 57-deg (87-deg ambient temp). Success.
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While the car was taken apart for the AC project, I took the opportunity to replace some of the trim and plastic components to upgrade the appearance. Many of the OEM black plastic components were faded and brittle.

These two plastic “appearance covers” were replaced with new OEM parts. These are located above the radiator, under the hood. Left = 04806117AC, Right = 04806116AC.

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The big plastic lower windshield cowl cover was also replaced with a new OEM unit, 4805834AD. This was pretty expensive, however the old one was worn out, and I can’t imagine that these will be available for new purchase much longer. I used new plastic push-rivets to secure the cowl cover – purchased at AutoZone, Needa P/N: 458100.

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Here is a pic of the engine bay with the new plastic covers.

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I also got a new windshield via Safelight, and new “refurbished” A-pillar plastic trim inserts. And I added the 2007+ SRT grille badge (Mopar 05030355AB). The 2006 cars did not have this badge from the factory. Is that considered up-badging? Haha, just kidding.

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Thanks for reading.
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I was on vacation in San Antonio visiting one of my daughters. A C died. With no tools, no time, and no place to do it. I couldn't find a shop to do it for at least two weeks! NorthStar Dodge had it done in a day and a half. $3500.00 and no K.Y. They did do a excellent job.
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Excellent write-up, Rez! I recently replaced everything except the evaporator. Your info on taking dash apart will be a huge help when the time comes - thanks!
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Very Nice.
I recently did mine also. Everything but the evaporator.
It's interesting because my compressor had 0 oil also. I have no idea where it went.
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Very Nice.
I recently did mine also. Everything but the evaporator.
It's interesting because my compressor had 0 oil also. I have no idea where it went.
Nice video, I'm glad you didn't need to replace the evap core - that adds massive additional complexity to the project!

Did you replace the little Schrader valves also? There are 3, one on each fill port, and one under the pressure sensor. Those are notorious for leaking.
Posts 3 & 4 updated with more pictures and updates.
Nice video, I'm glad you didn't need to replace the evap core - that adds massive additional complexity to the project!

Did you replace the little Schrader valves also? There are 3, one on each fill port, and one under the pressure sensor. Those are notorious for leaking.
I did not replace the schrader valves. So far everything seems to be still working great. I'm a believer in the old saying "If it's not broken, don't fix it."
I'm alittle surprised your temps aren't getting colder. I'm in FL and with temps 90*+ I'm still getting into the mid to low 40* in long cruises. When I'm in traffic it's alittle higher.
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Replace the schrader valves. The cost is nothing and they will fail.
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I'm alittle surprised your temps aren't getting colder. I'm in FL and with temps 90*+ I'm still getting into the mid to low 40* in long cruises. When I'm in traffic it's alittle higher.
Yeah, agreed. 57-deg felt ice cold and normal, maybe my temp gauge isn't working. I drove it again yesterday and it wouldn't go below 60, so it's being a little inconsistent.
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