Automotive Air Conditioning Information Forum

First let me thank the people here that have helped me over the last two months!
This evening my ongoing topic "Plans for 90 civic A/C rebuild with newer gen Sanden compressor - remaining questions" was locked by the administrator for link abuse. It was never my intent to violate rules or "advertise". My only reason for using this forum is to get advice on my specific situation from very knowledgeable people. The links were there to help describe what I have been doing and thinking, to provide background for my reasoning and encourage discussion.

I have since discussed this with Tim and will not be using links going forward. There will also be a minimum of pics. I will be continuing with new questions / topics where I don't already have answers that you have so kindly given already.

Just a little introduction: I'm a retired electrical engineer in hot and humid Florida. My dad started as a toolmaker apprentice in the 1920s and started teaching me how to use tools safely when I was age 5. I remember "helping" him fix our washing machine and noticed something he hadn't put back and spoke up. After he stopped yelling at me and realized he hadn't put it back he apologized. Best dad ever!

Your first post was not removed or any of the content. It was locked. Feel free to "ask" questions. Just respect my site. It's that simple. I have been running this site since 1997. This site costs money to run. No one at Amazon, eBay, or any other source pays these costs. While you might think this is directly related to you. It is not! It happens every summer.

Again, ask your questions. No need for Amazon reviews, parts images, and so on. If it is a specific image or stat for clarification. That is fine. But limit it to data that is truly needed for your question.

OK thanks for clarification. If it works for you, I will delete / edit old posts for which I now have answers. Is it OK for me to link back to the locked thread so others can find it if they are interested? Are the images with part numbers specs and brand names as I copied a problem if they don't have a link for the source? Let me know if that works.
Thanks,
Jim

This seems like a good opportunity to remind all members to kindly re-read the Forum rules. Item Number 8 covers links, which are not allowed.

Tim, Thanks for your patience. I have now removed the old posts from this topic since I have answers on most of those. If anyone is interested in the original locked topic, It is located in the Automotive Air Conditioning Procedures, Tips and FAQ forum.

I will continue with unanswered questions.

Last comment from me on this. I did not ask you to remove posts. If that is needed, a moderator or myself will do so. Just move on with any questions you might have.

To get new readers up to speed here is a quick summary of where we are in the project:

90 Civic being adapted to use newly manufactured Sanden 4993 used in the next gen Civic.

Initial attempts to find a new / not rebuilt TR-70 failed and led to much research over a few months. I found and studied the 4993 replacement threads in two Honda enthusiast forums for months. The 4993 I have shipped with the correct amount (130cc) of double end capped oil (SP-10) for the complete system.

I have already mounted the 4993 with the factory supplied shipping pads that seal in the SP-10 oil to keep it uncontaminated until the system can be finished (evacuated, leak tested and charged) by a yet to be determined shop (hopefully MACS accredited).

The system was previously converted to R143a by an honest but not expert local mechanic. The original TR-70 compressor appeared to be working, and the conversion only included a new receiver / drier and PAO 68 (Polyalphaolefin) - non hygroscopic, compatible with both R143a and mineral oil. At the time I thought that was probably the best choice over the correct PAG oil since the mechanic couldn’t get the old mineral oil completely out without removing the compressor. About a year later a refrigerant leak occurred. I took it back to the same mechanic who found a leak in the condenser and replace it with a parallel flow design. That repair worked for less than a year with the original TR-70 compressor which he concluded failed with a crack on its rear cover under its heat shield, dumping the charge and U/V dye. I doubt that diagnosis at this point since my later inspection after removing the compressor and heat shield shows no crack. The compressor was not locked up.

I suspect the more likely failure mechanism to have been over-pressure that blew the safety valve under the heat shield. Possible support for that:

1) Failure occurred on one of the hottest days of last summer during an extended drive. I heard the rapid loss of refrigerant and the system stopped working immediately.
2) The mechanic recharged the system, said it wasn’t leaking and took it for a successful test drive.
3) Upon picking up the car several hours later, there was no A/C and no pressure in system. That’s when the mechanic gave his diagnosis noting the U/V dye sprayed from the back of the compressor and recommended replacing the compressor.

Possible mechanisms for the over-pressure:

1) Blockage on the high side – condenser or TXV. I suspect insufficient flushing leaving wear particles and the PAO / mineral oil concoction may have led to blockage in the very small tubes of the parallel flow condenser.
2) Failure of the over-pressure switch in the liquid line to open, thus blowing the safety valve. The valve body is very corroded.
3) Missing foam blocks that seal the space between the edges of the condenser and radiator, lowering air flow through the condenser.

What do you guys think of this scenario? I'm open to any opinions, yay or nay. As a good friend used to say (unfortunately passed on) "I haven't been wrong since the last time."

Getting back to your previous questions, you had asked about the following:

"I know this sounds unorthodox, but could a detergent (surfactant such as Dawn dishwashing liquid + water) under pressure be used as a pre-flush before traditional flushing solvents to save on solvents (money+environmental hazard)?"

And, concerning reasons for the HPRV blow-off...

90efAACIF wrote: ↑Wed May 10, 2023 9:07 am 1) Blockage on the high side – condenser or TXV. I suspect insufficient flushing leaving wear particles and the PAO / mineral oil concoction may have led to blockage in the very small tubes of the parallel flow condenser.

I would forego using any water-based pre-flush, concerned that some moisture and/or detergent residue would remain in the system someplace and cause problems later. ACKITS.com stocks several products formulated specifically for A/C system flushing that are environmentally friendly, that will remove debris and old oil, and that evaporate completely. I recommend flushing only with one of those solvents.

Presume you meant "POE (Polyol Ester)/mineral oil concoction." Regardless, it's possible that if the shop flushed the system and didn't replace the PF condenser—which in addition to its primary purpose also acts as a debris filter—that it could have become clogged or partially clogged, leading to the high-pressure event.

If I remember correctly, TR70 was known to blow a hole in the side of the case when pressures got high. They were not an R134a conversion candidate. Just an expansion valve system. Nothing super tech to convert when you're using a different compressor. As mentioned, PF Condenser, new ac lines, drier, and "clean system". Follow normal charging procedures.

Never introduce water into the system.

""I know this sounds unorthodox, but could a detergent (surfactant such as Dawn dishwashing liquid + water) under pressure be used as a pre-flush before traditional flushing solvents to save on solvents"

Egads, how in the world did I miss this???!!!
Hopefully you haven't actually done this, because the system would never run correctly after such a flush. Ever. Anything put into an AC system has to be non-polar. Period