Question re: flushing A/C evaporator and expansion valve

I'm soon going to be replacing my damaged condenser, receiver, and high side liquid tubing. Other 1st Gen posts advised me to flush the system and replace o-rings before installing the new parts. (I believe the compressor is 100% A-OK even though it is original at 373,000 miles.) I can remove and flush the lines that go to and from the compressor, no problem. But if it won't hurt anything, I want to avoid removing the evaporator and expansion valve to flush them. Here's a how-to video from AutoZone, where the guy does not remove them to flush them:

https://www.autozone.com/diy/how-to/how-to-flush-your-cars-ac-system

Anyone have any advice on this? I assume I need to be sure to flush from the expansion valve inlet because that's the direction that the refrigerant goes in? Thanks everyone. Safe and happy wrenching to you.

 

If your not going to replace expansion valve ( I recommend you do) you'll want to flush the evaporator backwards from the normal flow. You want to push any foreign pieces away from the tiny expansion valve passage not through it 373k miles is a lot of miles on a compressor. I wouldn't reuse it.

 

If you haven't had a catastrophic failure of the compressor and/or the oil in the system isn't dark/grey then flushing isn't necessary.

You want to back flush the whole system with the exception of the compressor which should be removed from the equation. Flushing a TXV isn't recommended as you wouldn't usually be able to adequately clean them like that but if it's buried in the dash and there wasn't metal shrapnel from a compressor failure then I would try it.

When your compressor is removed, dump the oil, pour a bit of new oil through the inlet side, spin it a bit then dump that oil out the outlet then pour a bit more in the inlet then gauge it's health at that point.

I agree it's a high mileage compressor and replacement isn't a bad idea but the way I also looked at it with my 92 camry that I retrofit from R12 a few months ago is that sure it would be peace of mind but then if I do that then why not rip out the dash and change the TXV which theoretically will have a weakened spring and not meter optimally, the evaporator which is theoretically a hairs breathe from leaking, along with the heater core which is plugged surely to some degree while i'm there, then reseal/replace the hvac box and the cables and actuators. Not to mention the condensor and all the lines which are just as worn and probably about to leak... next thing you know you've replaced the whole car. And since the idea would be to avoid future issues I would be wanting to source OEM parts from somewhere which would be pricey to say the least

Changing all accessible seals on connections is as far as I would go seeing how it sounds like you have a clear part failure and something i've learned from my time both as amateur and professional is to not try fixing things that aren't broken... just my opinion though.

If you do a system flush, don't forget that you'll have to add a system worth of oil to replenish all the oil that'll flush out.