This is what my A/C is reading.

[Rilas]

You should be able to get some R134a hoses and just hook them to your current manifold gauge set. Honestly it's only the connectors on the end of the hoses that are different. R134a uses a newer quick release style like air compressor hoses have instead of screwing on.

[GTRON]

You should be able to get some R134a hoses and just hook them to your current manifold gauge set. Honestly it's only the connectors on the end of the hoses that are different. R134a uses a newer quick release style like air compressor hoses have instead of screwing on.

Ok, I thought that was the case.

[GTRON]

Can someone verify that I have this all straight in my head.

I need to replace my expansion valve, replace O-rings, retrofit r134a fittings, and vacuum system. There's a couple parts I'm confused on. How do you remove r12 oil from the system, and how much do you put back in with the r134a? Also, do I need to replace my drier?

Thank you guys so much, you're a life saver.

[Rilas]

Just follow this write up. I've done 3 systems now and have had no issues.

EXT : Gummiegorillas Do it Nice or Do it Twice A/C Retrofit !!

This has all the information you need to correctly do this job, including everything you asked about. Good luck .

[GTRON]

Just follow this write up. I've done 3 systems now and have had no issues.

EXT : Gummiegorillas Do it Nice or Do it Twice A/C Retrofit !!

This has all the information you need to correctly do this job, including everything you asked about. Good luck .

Yah, I've seen that, I'm not wanting to rebuild the system... There's no way I'm taking the compressor apart like that, haha.

[Rilas]

Really without taking the compressor apart you run the risk of "black death" which will render the system useless. So at this point your stuck with the entire rebuild or possibly no a/c at all unless you buy a new pump, or a junkyard pump and rebuild.

[GTRON]

Is it necessary to get a new drier?

[Rilas]

Yes but they aren't very expensive on rockauto.com. Even locally they might not be that expensive. I think I paid around $20 for my last one.

[GTRON]

Really without taking the compressor apart you run the risk of "black death" which will render the system useless. So at this point your stuck with the entire rebuild or possibly no a/c at all unless you buy a new pump, or a junkyard pump and rebuild.

What if I just replace the expansion valve, vacuum the system, and fill with a r12 substitute?

[GTRON]

Really without taking the compressor apart you run the risk of "black death" which will render the system useless. So at this point your stuck with the entire rebuild or possibly no a/c at all unless you buy a new pump, or a junkyard pump and rebuild.

What if I just replace the expansion valve, vacuum the system, and fill with a r12 substitute? Or just r12

[Rilas]

You could try that but most likely some of the o-rings need to be replaced as well. Considering the poor rubber is now 23-26 years old.

[GTRON]

You could try that but most likely some of the o-rings need to be replaced as well. Considering the poor rubber is now 23-26 years old.

Right.. If it keeps a vacuum I should be good though right?

[masospaghetti]

I've revived a bunch of old, defunct air conditioner systems without having to do a complete teardown. Is it the "wrong way to do it"? Maybe, but I've had good luck with it.

Regarding R-12 oil: Leave it in there, it will settle to the lowest point in the system and remain inert. Does not hurt anything. It's just mineral oil and it won't mix with R-134a.

Get some R-134a fittings for your R-12 gauge set, get a box of R-134a o-rings and replace the ones you disturb but leave the rest alone. IMO, the risk/reward for replacing all system o-rings is not worth it. BUT, you have to replace the receiver/drier no matter what, you are asking for big trouble if you don't. This part is super cheap and not hard to change.

You have a choice regarding oil. I've not found a consensus whether Ester or PAG oil is better for retrofits. PAG is probably better in an ideal scenario where you are doing a complete drain, flush, and refill. Ester is probably better in your case as it's supposed to be more friendly to residual R-12 and mineral oil. You can either get liquid oil and pour it into the compressor and drier directly (but be sure to spin the compressor a few times by hand so it doesn't lock up when you first engage), OR you can get Ester in an aerosol can and shoot it through the port. Both will work.

Get R-134a from Amazon (about $19 for 3 cans of Dupont) or I saw at Walmart they have R-134a for about $4.50 a can. Avoid the auto parts stores as they will rip you off big time and charge about $20 per can.

Change the receiver/drier, vacuum the system down, make sure it holds, and fill with oil and refrigerant and you should be good to go.

R-134a is so cheap now that even if you have an o-ring fail six months or a year from now, its not a big deal to refill it. But I think chances are good that you won't have any problems.

[GTRON]

I've revived a bunch of old, defunct air conditioner systems without having to do a complete teardown. Is it the "wrong way to do it"? Maybe, but I've had good luck with it.

Regarding R-12 oil: Leave it in there, it will settle to the lowest point in the system and remain inert. Does not hurt anything. It's just mineral oil and it won't mix with R-134a.

Get some R-134a fittings for your R-12 gauge set, get a box of R-134a o-rings and replace the ones you disturb but leave the rest alone. IMO, the risk/reward for replacing all system o-rings is not worth it. BUT, you have to replace the receiver/drier no matter what, you are asking for big trouble if you don't. This part is super cheap and not hard to change.

You have a choice regarding oil. I've not found a consensus whether Ester or PAG oil is better for retrofits. PAG is probably better in an ideal scenario where you are doing a complete drain, flush, and refill. Ester is probably better in your case as it's supposed to be more friendly to residual R-12 and mineral oil. You can either get liquid oil and pour it into the compressor and drier directly (but be sure to spin the compressor a few times by hand so it doesn't lock up when you first engage), OR you can get Ester in an aerosol can and shoot it through the port. Both will work.

Get R-134a from Amazon (about $19 for 3 cans of Dupont) or I saw at Walmart they have R-134a for about $4.50 a can. Avoid the auto parts stores as they will rip you off big time and charge about $20 per can.

Change the receiver/drier, vacuum the system down, make sure it holds, and fill with oil and refrigerant and you should be good to go.

R-134a is so cheap now that even if you have an o-ring fail six months or a year from now, its not a big deal to refill it. But I think chances are good that you won't have any problems.

That's really helpful! Thank you!
I'm still confused about the oil thing though. If you're not taking any out (besides the drier), how do you know how much to put in by itself, and with the freon?

I'm having a shop quoting $75 just to tell me what's wrong with the system... I can buy a vacuum and retrofit parts for that! Also, I would rather skip the hassle of retrofitting, and just put in a r-12/r134a substitute like enviro-cool? Sure it's more for refrigerant, but less chance of something quitting with the increased load of r134a.

[masospaghetti]

Head pressures are a bit higher with R-134a but performance is very predicable. I've never used those drop-in substitutes, they might work well, just be warned that a shop won't touch your system after you fill it with a non-standard refrigerant and also be aware of special procedures they might require. Redtek R-12a, for example, specifically says NOT to vacuum the system down - why, I have no idea.

There's also flammability. R-134a is basically non-flammable. Most drop-in substitutes are hydrocarbon based (butane, propane, etc). They claim to non-flammable but that would still make me nervous. The a/c system was not designed to contain a flammable gas in a collision.

Regarding oil quantity, use the factory fill amount for adding new Ester oil. The old oil is basically irrelevant at this point. You need a complete charge of the new stuff. I have a Honda PDF that says the system takes 8 oz total, you might want to double check this value but it would be a good place to start.

A/C service is really the low-hanging fruit of auto repair IMO as you are discovering. It's expensive to have a shop do it and it's really not that difficult to do. Keep at it and you'll have yourself a very useful skill and very useful set of shop tools!