Oh no, not another r134a conversion topic!

[Comunchy]

hi

 

My truck still has the original r12 AC system in place. It was working great but I needed to discharge it ahead of a heater core job I did last fall and now I'm considering an r134a conversion instead of recharging it with the very expensive and increasingly scarce r12. Less concerned with r134a blowing less cold - I don't need arctic wind blasting out of this baby because it only gets up to 90 for a few days out of the year where I live. Not considering an AC delete at this time.

 

I'm new to AC maintenance and I've been finding a wide variety of info online regarding what actually needs to be done for the conversion vs. what people choose to do - all the way from "slap some adapter fittings on there and recharge it with r134a" up to "replace it all, even the evaporator and condenser." I've read some previous threads here on CC to generally educate myself but looking for someone with a little more experience to weigh in on what I plan to do specifically.

 

At a minimum, here is what I think I need to do:

1. Replace the receiver drier and O rings
2. Replace the expansion valve & block and O rings
3. Flush the system
4. Pull vacuum and test
5. Add PAG oil
6. Recharge with r134a (~80% less than the amount of r12)
7. Drink beer while the AC blows cold air in my face

 

Things I'm not sure about:

1. Do I also need to replace the compressor? If it's not required, SHOULD I replace the compressor as a part of the job? Mine is OEM and I'm not sure how often these fail. I'd rather do it now than later but I don't want to spend the money if these rarely go out.
2. If I replace the compressor too, does this change any of the steps above?
3. Same question for the A/C lines. Visually they look like they've seen better days, but I'd prefer to save this for a future, bigger project if it doesn't need to be done right now. There were no leaks previously so considering that a non-issue.
4. I don't think it's required to replace the evaporator or the condenser if I do a system flush before recharging with r134a. From what I've seen, people are only replacing these if there are existing problems (such as an evaporator leak). But I would like confirmation of this.

 

Thanks for your help.

 

P.S. Maybe I can contribute to this dusty thread after it's wrapped up:

 

[eaglescout526]

Did you watch the video on this topic by nickintimefilms? He covered it pretty well for those who still have the original Renix R12 fittings in place. I would provide more but I can't and only added AC to mine. @Minuit would be the man to have the most knowledge on here about AC systems. 

 

Now I can take a stab at some of these.

 

1.If you have never ever replaced the compressor, it wouldnt hurt to get a R134a compliant compressor just to save a headache. That being said an expansion valve and 2.condenser should be swapped for the new stuff too as should your dryer.

Replacing the compressor shouldnt affect anything else. You can keep the original R12 fittings and get those R134a adaptors to save you money of you could find straight R134a fittings for the compressor and be done with such.

3.If the lines check out visually and internally then just make sure they are well cleaned out of any moisture from both the R12/mineral oil and water. If you think you should replace the lines, go to your local auto store and have them send off the hose to be made new by their vendors as not everyone carries the old Jeep AC lines in stock.

4.Evap is fine to keep, just do the same as above with cleaning it out. I reused an old Renix evap and its been fine for the year I have had it. I made sure to blow it out and keep it dry until it was time to install. 

 

In short you might be looking at a refresh with your conversion.

[Comunchy]

6 minutes ago, eaglescout526 said:

Did you watch the video on this topic by nickintimefilms? He covered it pretty well for those who still have the original Renix R12 fittings in place. I would provide more but I can't and only added AC to mine. @Minuit would be the man to have the most knowledge on here about AC systems. 

 

Now I can take a stab at some of these.

 

1.If you have never ever replaced the compressor, it wouldnt hurt to get a R134a compliant compressor just to save a headache. That being said an expansion valve and 2.condenser should be swapped for the new stuff too as should your dryer.

Replacing the compressor shouldnt affect anything else. You can keep the original R12 fittings and get those R134a adaptors to save you money of you could find straight R134a fittings for the compressor and be done with such.

3.If the lines check out visually and internally then just make sure they are well cleaned out of any moisture from both the R12/mineral oil and water. If you think you should replace the lines, go to your local auto store and have them send off the hose to be made new by their vendors as not everyone carries the old Jeep AC lines in stock.

4.Evap is fine to keep, just do the same as above with cleaning it out. I reused an old Renix evap and its been fine for the year I have had it. I made sure to blow it out and keep it dry until it was time to install. 

 

In short you might be looking at a refresh with your conversion.

 

Awesome, thanks for pointing me in the direction of that video. I haven't watched it but I will do so shortly. Thanks as well for the additional info regarding the condenser and compressor. I'm leaning towards just swapping the compressor since I'll already be in there - and like you said, maybe avoiding a future headache.

[eaglescout526]

No problem! I think it would be much easier to swap out a compressor than to sit there and drain it of all the oil and then fill it back up to the appropriate level.

 

Keep an eye out from minuit with a lengthy response on the topic. 

[JustEmptyEveryPocket]

Check out this stuff. 

 

[Minuit]

58 minutes ago, Comunchy said:

hi

 

My truck still has the original r12 AC system in place. It was working great but I needed to discharge it ahead of a heater core job I did last fall and now I'm considering an r134a conversion instead of recharging it with the very expensive and increasingly scarce r12. Less concerned with r134a blowing less cold - I don't need arctic wind blasting out of this baby because it only gets up to 90 for a few days out of the year where I live. Not considering an AC delete at this time.

 

I'm new to AC maintenance and I've been finding a wide variety of info online regarding what actually needs to be done for the conversion vs. what people choose to do - all the way from "slap some adapter fittings on there and recharge it with r134a" up to "replace it all, even the evaporator and condenser." I've read some previous threads here on CC to generally educate myself but looking for someone with a little more experience to weigh in on what I plan to do specifically.

 

At a minimum, here is what I think I need to do:

1. Replace the receiver drier and O rings
2. Replace the expansion valve & block and O rings
3. Flush the system
4. Pull vacuum and test
5. Add PAG oil
6. Recharge with r134a (~80% less than the amount of r12)
7. Drink beer while the AC blows cold air in my face

 

Things I'm not sure about:

1. Do I also need to replace the compressor? If it's not required, SHOULD I replace the compressor as a part of the job? Mine is OEM and I'm not sure how often these fail. I'd rather do it now than later but I don't want to spend the money if these rarely go out.
2. If I replace the compressor too, does this change any of the steps above?
3. Same question for the A/C lines. Visually they look like they've seen better days, but I'd prefer to save this for a future, bigger project if it doesn't need to be done right now. There were no leaks previously so considering that a non-issue.
4. I don't think it's required to replace the evaporator or the condenser if I do a system flush before recharging with r134a. From what I've seen, people are only replacing these if there are existing problems (such as an evaporator leak). But I would like confirmation of this

 

 

@eaglescout526 Done and done. I was about 3/4 of the way through writing this when I saw you mentioned me in your post. I've got a nose for these A/C threads, you see.

 

The list of things you need to do is correct. If I were you, I'd make the following changes:

 

- Add the oil when assembling the system, not after leak checking - it won't go anywhere when pulling a vacuum. I'd probably put all of it in the compressor but rotate the compressor 20 or so times by hand immediately before the first startup and charge.

 

- Dismount the compressor and drain it of the old oil. Rotate the inner clutch hub and ensure that it spins freely with no binding through the entire rotation. It should also make "bloop bloop" noises through the hose connections while you're doing this. Also, make sure the outer pulley spins freely with no noise. Otherwise, replace the compressor with a new unit.

 

1. You don't have to, no. Your truck will have an SD508 compressor which is still readily available new if you decide to replace it. It probably leaks oil through the front seal, and has probably coated the area above it on the hood in a layer of black gunk (that's A/C refrigerant oil). Considering the SD508 compressor may be the single most common A/C compressor of this era, I'd replace it. If you do decide to replace the compressor, replace it with a new, not a reman, unit.

 

2. You'll need to check the amount of oil that comes in the new compressor. I suggest draining the old compressor anyway, so not really a big deal. Final charge should be roughly 30 oz of refrigerant (I've already done the conversion for you) and 6 oz of PAG 100 oil.

 

3. Lines intended for R-12 use will gradually weep R-134a through the hose, but this is such a slow process that it's really not worth worrying about. Replace the lines if they show cracks or signs of damage - you'll probably have to get them made by a hose shop. Any good hose shop should be able to make you an A/C line that's an exact copy of what you bring them.

 

4. The condenser is your best chance to pick up an improvement in cooling performance - replacing it with a "parallel flow" style condenser will go a long way to offset the difference in cooling performance between the refrigerants. APDI makes one - part number 7014173. Was a direct fit in my '91, should be a direct fit in your '90. The old condenser is probably falling apart anyway. They do that. The time to replace the evaporator was when you replaced your heater core, but common practice is to only replace them when there's a problem. When/if your evaporator springs a leak, @ghetdjc320 has pioneered swapping in a later model evaporator for better performance, if you're willing to experiment.

 

Source: EPA 609 Certified Motor Vehicle A/C Technician, my '91 MJ has A/C that works, etc, etc, blah blah blah...

[eaglescout526]

2 minutes ago, Minuit said:

@eaglescout526 Done and done. I was about 3/4 of the way through writing this when I saw you mentioned me in your post. I've got a nose for these A/C threads, you see.

 

Thats pretty good lol. 

[Minuit]

A couple of other things that might help you out if you're new to this, that you may or may not have heard before:

 

- No stop leak. Ever. It will ruin the system. The only things that should be in an A/C system are refrigerant, oil, and a tiny bit of dye. 1/4 oz of dye is plenty for the whole system.

- Always be clean when working with A/C stuff. Cleaning fittings before taking them apart to prevent dirt from getting inside is a good idea, as is washing your hands every few minutes. A/C is a closed system with either no or next to no filtration (I haven't cut open an MJ receiver/drier to check), so junk that gets in stays in.

- Just go ahead and buy an HNBR o-ring assortment box right now. If you drop an o-ring on the ground, it's garbage. You're going to drop an o-ring on the ground. Related, give every o-ring a little dab of PAG oil before putting the parts together.

 

As to other R-12 replacement refrigerants, that's a matter of opinion, and they WILL work, but they aren't a substitute for the type of work that the OP needs to do to get his system back on the road after being discharged, disconnected, and left empty for an extended amount of time. Most of them are flammable, and that's not really my thing.

[Comunchy]

7 minutes ago, Minuit said:

 

@eaglescout526 Done and done. I was about 3/4 of the way through writing this when I saw you mentioned me in your post. I've got a nose for these A/C threads, you see.

 

The list of things you need to do is correct. If I were you, I'd make the following changes:

 

- Add the oil when assembling the components - it won't go anywhere when pulling a vacuum. I'd probably put all of it in the compressor but rotate the compressor 20 or so times by hand immediately before the first startup and charge.

 

- Dismount the compressor and drain it of the old oil. Rotate the inner clutch hub and ensure that it spins freely with no binding through the entire rotation. It should also make "bloop bloop" noises through the hose connections while you're doing this. Also, make sure the outer pulley spins freely with no noise. Otherwise, replace the compressor with a new unit.

 

1. You don't have to, no. Your truck will have an SD508 compressor which is still readily available new if you decide to replace it. It probably leaks oil through the front seal, and has probably coated the area above it on the hood in a layer of black gunk (that's A/C refrigerant oil). Considering the SD508 compressor may be the single most common A/C compressor of this era, I'd replace it. If you do decide to replace the compressor, replace it with a new, not a reman, unit.

 

2. You'll need to check the amount of oil that comes in the new compressor. I suggest draining the old compressor anyway, so not really a big deal. Final charge should be roughly 30 oz of refrigerant (I've already done the conversion for you) and 6 oz of PAG 100 oil.

 

3. Lines intended for R-12 use will gradually weep R-134a through the hose, but this is such a slow process that it's really not worth worrying about. Replace the lines if they show cracks or signs of damage - you'll probably have to get them made by a hose shop. Any good hose shop should be able to make you an A/C line that's an exact copy of what you bring them.

 

4. The condenser is your best chance to pick up an improvement in cooling performance - replacing it with a "parallel flow" style condenser will go a long way to offset the difference in cooling performance between the refrigerants. APDI makes one - part number 7014173. Was a direct fit in my '91, should be a direct fit in your '90. The old condenser is probably falling apart anyway. They do that. The time to replace the evaporator was when you replaced your heater core, but common practice is to only replace them when there's a problem. When/if your evaporator springs a leak, @ghetdjc320 has pioneered swapping in a later model evaporator for better performance, if you're willing to experiment.

 

Yes, my compressor is leaking a little bit of oil through the front seal - but no black gunk on the hood yet... I think I'm just going to replace it. I'll be sure it's new and not reman.

 

I'll do an in depth visual check on the lines and go from there. Maybe I'll get a quote on the lines just as a point of reference for the future.

 

Thanks for the detailed info including part numbers for the improved condenser and the conversion measurements. I might research this a bit more but if my lines don't need to be replaced maybe I'll spring for the $60 to replace it too.

 

 

 

16 minutes ago, JustEmptyEveryPocket said:

Check out this stuff. 

 

 

Interesting, I'll check this out as well! I'd seen some of the r12 substitute chemicals in my research but wasn't sure how legit they were. Sounds like folks have had good experiences with at least one brand. My concern so far is that they appear to be flammable and that makes me a little nervous - maybe that's unwarranted though.

 

 

These replies are all awesome. Thanks so much for the advice everyone!

[Minuit]

26 minutes ago, Comunchy said:

Interesting, I'll check this out as well! I'd seen some of the r12 substitute chemicals in my research but wasn't sure how legit they were. Sounds like folks have had good experiences with at least one brand. My concern so far is that they appear to be flammable and that makes me a little nervous - maybe that's unwarranted though.

I'm nervous about them too. Here's my line of thinking.

 

The condenser is on the high side of the system, and depending on the temperature the pressure inside of it can push 300psi. Worst case, one in a million scenario: You hit someone, or get hit yourself, and the condenser gets punctured, and a spark is generated in just the right spot to ignite the refrigerant streaming out of the hole in the condenser. WHOOOOSH as a fireball streams out of the front of your truck. If your insurance gets a hold of that and realizes that that is by no means a normal occurrence, what are they gonna think of that? And if somehow someone finds out that you put a mix of flammable chemicals in your A/C system because we told you to, I don't want to cop the liability for that.

 

Of course, the refrigerant that is most common in new cars these days, R-1234yf, is mildly flammable too under some fairly specific circumstances, but 1234yf's flammability was a big deal in the industry until it wasn't. I wouldn't bother to use propane, or any R-12 replacement hydrocarbon blend in my vehicle, but I'm also not the target market for the companies selling it either.

 

Also @Comunchy - do you have manifold gauges?

[Comunchy]

That's not the kind of fireball I want coming out of my truck...

 

I don't have any manifold gauges yet, but I have them on my list of equipment to buy / borrow / rent in order to get the job done (along with a vacuum pump).

[jdog]

17 minutes ago, Minuit said:

Of course, the refrigerant that is most common in new cars these days, R-1234yf, is mildly flammable too under some fairly specific circumstances, but 1234yf's flammability was a big deal in the industry until it wasn't.

Iirc Mercedes had it catch fire on their test track and didn't want to convert because of it. If you look on the labels for the new ones they have the flammable symbol.

 

Onto the original question, what is the reason to switch? If it's cause the a/c isn't cold you will need to verify it's not leaking anywhere before you start my else. Also if the lines have been off longer then a couple hours replace the dryer.

[Comunchy]

4 minutes ago, jdog said:

Iirc Mercedes had it catch fire on their test track and didn't want to convert because of it. If you look on the labels for the new ones they have the flammable symbol.

 

Onto the original question, what is the reason to switch? If it's cause the a/c isn't cold you will need to verify it's not leaking anywhere before you start my else. Also if the lines have been off longer then a couple hours replace the dryer.

 

I'm considering making the switch because I already had the r12 discharged for a different project and it's pretty expensive to refill it with r12 (and will be expensive to refill again if I need to discharge the system for some other reason / there is a future leak or failure) so I'm thinking of converting. It worked fine before it was discharged.

 

It's been a few months since the discharge - I definitely have the drier replacement on the list of must-dos.

[jdog]

ah yeah then that will be good, follow minuits advice and you should be good to go.

[Minuit]

31 minutes ago, Comunchy said:

That's not the kind of fireball I want coming out of my truck...

 

I don't have any manifold gauges yet, but I have them on my list of equipment to buy / borrow / rent in order to get the job done (along with a vacuum pump).

I wouldn't want to use a rented set. Other than that, pretty much anything you can buy will do you fine.

[Comunchy]

Sounds like a good excuse to buy a pair!

[jdog]

i believe harbor freight sells some that will work. don't know about longevity

[AZJeff]

I have done conversions from R12 on several vehicles with success, I will attest that all of Minuit’s recommendations are spot on.  
 

For special tools, I bought a set of gauges/manifold from the local auto parts store, and a vacuum pump from Harbor Freight.  They have served me well for 15 years.