Factory A/C System Flush?

[kna4977]

What's the best recommended way to flush a factory system? Product or products to use and best practices? I've flushed other systems before but it's been years. I would like to keep the original condenser if possible what's the best way to flush that? I'm going to replace the drier. Everything else is pretty much new or can be flushed I think.

[boz42]

I take as many pieces off the system as easily possible so that I am not pushing trash further into the system. I use a pressurized flush can (I use nitrogen to pressurize the can) and A/C solvent to blow thru the pieces. Lots of people use shop air, and it will work but shop air typically has moisture and trash from the lines and tank in it.

You didn't say which refrigerant you are going back with. You should make sure that the flush solvent is compatible with the refrigerant. I use this solvent:
https://www.napaonline.com/en/p/TEM4...kKb2983g4V48v1

Here is an example of the flush canister:
https://www.napaonline.com/en/p/NTE7...dJg4wFCFyAC-uO


As far as parts, I would consider a kit like this for the replacement parts:
https://www.cjponyparts.com/old-air-...IaAsPBEALw_wcB

[kna4977]

Sorry it’s 134 and ester

[kna4977]

Is there a trick to getting the POA valve apart from the evaporator? I’ve got everything else disconnected but that and it won’t budge.

[RichardJ]

>>Sorry it’s 134 and ester<<

So, it's a system with Mineral oil and you really can't flush a compressor, other than with hand pumping new Ester oil through it. Although I read on the forums some try to flush with solvent, or at least they think they are.
I separate the condenser and evaporator from everything and flush in both directions until fresh solvent flush goes out clean as it went in.
Nitrogen would be better, but I use compressed air with a moisture separator and filter. After I have it partially buttoned up, I purge the system with the 134. I know, you're not supposed to vent that much coolant out into the atmosphere. You do it again, to a lesser extent, when you purge the gauge lines.

[kna4977]

Originally Posted by RichardJ

>>Sorry it’s 134 and ester<<

So, it's a system with Mineral oil and you really can't flush a compressor, other than with hand pumping new Ester oil through it. Although I read on the forums some try to flush with solvent, or at least they think they are.
I separate the condenser and evaporator from everything and flush in both directions until fresh solvent flush goes out clean as it went in.
Nitrogen would be better, but I use compressed air with a moisture separator and filter. After I have it partially buttoned up, I purge the system with the 134. I know, you're not supposed to vent that much coolant out into the atmosphere. You do it again, to a lesser extent, when you purge the gauge lines.

Minimal if any mineral oil left in it. It was converted to 134 before I got it and had PAG oil in it. I use Ester because it's compatible with everything. The compressor is new.

My biggest issue right now is getting the POA valve off of the evaporator. Is there a trick to it? It's like it's cemented in place. Original POA and evaporator.

[jumpsoffrock]

Originally Posted by kna4977

Is there a trick to getting the POA valve apart from the evaporator? I’ve got everything else disconnected but that and it won’t budge.

I just removed a POA from another GM car recently, and after soaking it with penetrate for a week--which I think did nothing--I used two adjustable wrenches with 4' pipes on the end. I used one as a "brace" so I put minimal stress on the actual Evap piping.

My "nut" on the evap line was absolutely frozen, so I actually had to bend the evap line *slightly* which would allow the POA to spin off the nut. I then spent an hour very patiently and slowly trying to break the nut free, which it did with me freaking out because the car I'm working on has ZERO aftermarket AC parts and I woulda been screwed if I broke it.


I also had to use 4' pipes--same exact process--for the bottom evap line connected to the TXV.


FYI, even with very thick adjustable wrenches and 4' pipes, I was extremely surprised by the amount of force I had to put into it to break both the POA and TXV free.
Engine was removed at time of this job.

[kna4977]

I got everything apart. On the evaporator core, should there be any resistance at all to air or liquid or should it flow just like out of a hose an instantly?

I’ve flushed it both ways. All liquid is clear coming out, but it seems like it takes a little bit to build up pressure and for the liquid to come out. Not sure if this is normal or not, but trying to decide whether to replace the core or if this one is functioning as it should. It doesn’t leak at all. It’s the original one and is in great shape at least on the outside. Not sure how to tell if there is a partial blockage or not or if it’s normal for to have some resistance.

[jumpsoffrock]

I believe the evap is really just another radiator, yes there should be a tiny "delay" to get stuff coming out, but it shouldn't be considerable.
I'm sorry to let you down, but I also don't know how to test the evap without wasting a considerable amount of time and resources.
Removal is totally out of the question.

I am getting to a point at my age in life: run it and if it fails try again later.

I spent way too many months and years getting nowhere by trying to be "politcally correct" and test EVERY SINGLE LITTLE THING.

I'd spent months reading about welding instead of just doing it.


What am I gonna do with my current AC system?
I'm gonna put it together and try and pull vacuum with a cheap rental vac pump from oreillys. If I have a leak I'll resolve it.

Then I'll charge it and run it.

If acid eats a hole in my system because I'm stupid and didn't take 34 different precautions like the pros do? I guess I'll learn the hard way.



I spent a long time reading about AC stuff and some people say "just do it", and other people give you a list of 150 things that must be PERFECT before you even THINK about adding refrigerant.

I don't have that time anymore. But my advice is to try and weigh precautions with paranoia from internet experts.

[Richard]

134a works best with more heat rejection than the stock condenser type and mounting can provide. This is one reason why some say the newer refrigerant does not work as well..

[kna4977]

Originally Posted by jumpsoffrock

I believe the evap is really just another radiator, yes there should be a tiny "delay" to get stuff coming out, but it shouldn't be considerable.
I'm sorry to let you down, but I also don't know how to test the evap without wasting a considerable amount of time and resources.
Removal is totally out of the question.

I am getting to a point at my age in life: run it and if it fails try again later.

I spent way too many months and years getting nowhere by trying to be "politcally correct" and test EVERY SINGLE LITTLE THING.

I'd spent months reading about welding instead of just doing it.


What am I gonna do with my current AC system?
I'm gonna put it together and try and pull vacuum with a cheap rental vac pump from oreillys. If I have a leak I'll resolve it.

Then I'll charge it and run it.

If acid eats a hole in my system because I'm stupid and didn't take 34 different precautions like the pros do? I guess I'll learn the hard way.



I spent a long time reading about AC stuff and some people say "just do it", and other people give you a list of 150 things that must be PERFECT before you even THINK about adding refrigerant.

I don't have that time anymore. But my advice is to try and weigh precautions with paranoia from internet experts.

My evaporator is out. In fact everything is out so that I could clean it all the best way. Maybe I should just replace it, but don’t want to spend $350 if it’s not needed. It flows both ways. Air is no problem either way. All liquid coming out is clear both ways, but it does take a little bit to build up pressure before any liquid comes out when flushing. Either in the direction it flows or the opposite way. At first when flushing it, the oil would come flying out after pressure built up. Made a real mess.

[clay68c10]

Sounds clean to me.
Charge it and run it. If it doesn't cool great at high ambient temps, get a parallel flow condenser.

[kna4977]

Originally Posted by clay68c10

Sounds clean to me.
Charge it and run it. If it doesn't cool great at high ambient temps, get a parallel flow condenser.

Any recommendations? Are there any that look close to the original?

[clay68c10]

Cold Hose sells them by size. I've seen them on Ebay also.
I'm not sure if any of the usual vendors has them.