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Air Conditioning Questions, Need Opinions.


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Ok guys, I know this probably comes up fairly often, but I'd like to get the A/C in the MJ up and running the best I can ...on a budget.

 

When I did the engine swap in my MJ last year, I retained the factory A/C stuff in hopes of eventually having it work.  All components came from an '88 and '90 XJ donor.  The majority of the line ends have had the O-rings replaced.  The exception is the lines that run to and from the expansion tank.  At the condenser and up to the firewall, and on the compressor side, it's got new O-rings.

I've been reading up on R-12 to R-134a conversions, but from what I've gathered, that requires new hoses, a new dryer/receiver/whatever it's called and a complete flush of the system, then after all that, it's 20-30% less cold than R-12.

 

My dad has two (I think 12 ounce) cans of R-12 from the early '90s.  Would it be easier and more cost effective to charge it with R-12?  Also, would 2 cans even be enough from dead empty?

 

I want A/C since the humidity in eastern NC is retardedly high.

What else should I do or check before I get to work on all this?  I don't want the R-12 (or R-134a) to leak out (and into the atmosphere), especially considering R-12 is so hard to find and not even legal for me to buy.

:bowdown: 

 

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You'll need to flush the entire system. That means taking it apart.

 

You'll need to drain the oil from the compressor and add 134a oil.

 

Replace the accumulator and expansion valve, all O-rings.

 

 

You'll need at least three cans.

 

The entire system will need to be vacuumed down before recharge.

 

 

If you use the two cans of R12, and find a third.......of you have a failure or leak..........SOL and start all over again.

 

And I am not convinced of 30% less cool either........I call BS.

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The XJ/MJ A/C system capacity requires 24 oz. of refrigerant. If the R12 cans you have are 14 oz./ea, it might  be sufficient. But first, if you don't have a vacuum pump, you'll need to go to a shop and have them pull a vacuum and check for leaks.

 

I'm still hanging in there with R12, and usually have to recharge (one can) every other year. I still have a small stash of R12 left over.

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The XJ/MJ A/C system capacity requires 24 oz. of refrigerant. If the R12 cans you have are 14 oz./ea, it should be sufficient. But first, if you don't have a vacuum pump, you'll need to go to a shop and have them pull a vacuum and check for leaks.

 

I'm still hanging in there with R12, and usually have to recharge (one can) every other year. I still have a small stash of R12 left over.

Shop that will vacuum down my system.....when I get around to installing it......told me 3 cans of 134a

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You'll need to flush the entire system. That means taking it apart.

 

You'll need to drain the oil from the compressor and add 134a oil.

 

Replace the accumulator and expansion valve, all O-rings.

 

 

You'll need at least three cans.

 

The entire system will need to be vacuumed down before recharge.

 

 

If you use the two cans of R12, and find a third.......of you have a failure or leak..........SOL and start all over again.

 

And I am not convinced of 30% less cool either........I call BS.

 

I'm going off what I read on the interwebz, which I wouldn't presume as factual haha.  I'm a complete virgin when it comes to how the A/C stuff works.

 

Anyway, so from what you've said, I need to find a third can of R-12.  That would be the simpler solution to this, huh?  I guess I'll take the time to replace the last few O-rings that I neglected previously.

 

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You'll need to flush the entire system. That means taking it apart.

 

You'll need to drain the oil from the compressor and add 134a oil.

 

Replace the accumulator and expansion valve, all O-rings.

 

 

You'll need at least three cans.

 

The entire system will need to be vacuumed down before recharge.

 

 

If you use the two cans of R12, and find a third.......of you have a failure or leak..........SOL and start all over again.

 

And I am not convinced of 30% less cool either........I call BS.

 

I'm going off what I read on the interwebz, which I wouldn't presume as factual haha.  I'm a complete virgin when it comes to how the A/C stuff works.

 

Anyway, so from what you've said, I need to find a third can of R-12.  That would be the simpler solution to this, huh?  I guess I'll take the times to replace the last few O-rings that I neglected previously.

 

 

Hornbrod may be correct on the R12 system only requiring 2 cans........there may be a volume difference between the two freons..........IDK.

 

I'm only going by what the shop told me to pick up.

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Well, I should have noted in my initial post that I have a guy who normally only works on Volvos exclusively, and he has a vacuum system.  He just fixed my dad's A/C in his '90 Volvo.  We inquired about doing so on my MJ and since I'm having him do all this, I just wanted to be fully prepared when I get ready to bring it over to him.  So, vacuuming the system is also the way to discover leaks in the system?  I was going to get some UV dye to put in as well to find potential leaks.

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  • 4 weeks later...

Finally got around to the guys house...

We pulled a vacuum on it and it checked out fine.  However, due to the limited availability and expense of R-12, he recommended going ahead and converting it over to R-134a.

Here's what I've been told and have seen reported on various threads, including this one:

 

  • New accumulator/dryer/receiver (I assume all three refer to the same thing)
  • New expansion valve
  • Blow out lines with compressed air to remove leftover old oil
  • Drain compressor of old oil
  • New O-rings, the green ones (I've already taken care of this step when I did the engine swap)

My question is, when I start shopping for a new accumulator and expansion valve, do I just get a new one for the same year as my MJ?  Serious question, I don't know if they're designed differently between R-12 systems and R-134a systems.  Also, is there anything else I need besides the aforementioned parts to make this a successful conversion?  I'm going to make a RockAuto order soon.

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Finally got around to the guys house...

 

We pulled a vacuum on it and it checked out fine.  However, due to the limited availability and expense of R-12, he recommended going ahead and converting it over to R-134a.

Here's what I've been told and have seen reported on various threads, including this one:

 

  • New accumulator/dryer/receiver (I assume all three refer to the same thing)
  • New expansion valve
  • Blow out lines with compressed air to remove leftover old oil
  • Drain compressor of old oil
  • New O-rings, the green ones (I've already taken care of this step when I did the engine swap)

My question is, when I start shopping for a new accumulator and expansion valve, do I just get a new one for the same year as my MJ?  Serious question, I don't know if they're designed differently between R-12 systems and R-134a systems.  Also, is there anything else I need besides the aforementioned parts to make this a successful conversion?  I'm going to make a RockAuto order soon.

 

 

FWIW, R-12 is a more efficient refrigerant than R-134a. This is because R-12 requires less pressure to achieve the same cooling as R-134a, but like you know already R-12 is un-obtainium, so in the long run R-134a is the wiser choice.

 

 

 

As for your question about the drier and expansion valve, R-12 or R-134a i don't think it matters so long as you get parts that are close to your relative year.

 

 

It is very important that you add the correct TYPE and AMOUNT of compressor oil or you can really fudge things up. You might want to consider throwing a little bit of a/c dye as well for future leaks, should they occur. Also you said you have already pulled vacuum, but how long did you let it sit with the pump off before you checked?

 

In conjunction with the compressed air, there is such a thing as "a/c flush" and could be beneficial to you. How old is your evaporator and/or condenser? It is good insurance to at least replace the condenser, especially if it is the factory unit. If you use a flush i think you will be okay, but if you want to be sure, replace.

 

 

 

Hope everything works out, theres nothing sweeter than an MJ with working a/c. B)

 

 

FPC.

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You might want to consider throwing a little bit of a/c dye as well for future leaks, should they occur. Also you said you have already pulled vacuum, but how long did you let it sit with the pump off before you checked?

The dye is a good suggestion. We let it sit for about 30 minutes with the pump off and it held vacuum consistently the whole time.

 

I ordered mine as a kit from rockauto. Came with accumulator, compressor, orings, and valve. $191 to my door.

 

The 'kit' is listed right under compressor listing.

 

I'm thinking about going this route.  Didn't realize it would be that inexpensive.

 

 

I'll be sticking with R12. Just picked up a six year supply for $50. Since the system has been hanging tough now for 23 years, there are too many variables and expenses to convert.

 

Where did you get that?!  That's what I need.

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You might want to consider throwing a little bit of a/c dye as well for future leaks, should they occur. Also you said you have already pulled vacuum, but how long did you let it sit with the pump off before you checked?

The dye is a good suggestion. We let it sit for about 30 minutes with the pump off and it held vacuum consistently the whole time.

 

I ordered mine as a kit from rockauto. Came with accumulator, compressor, orings, and valve. $191 to my door.

 

The 'kit' is listed right under compressor listing.

I'm thinking about going this route. Didn't realize it would be that inexpensive.

 

I'll be sticking with R12. Just picked up a six year supply for $50. Since the system has been hanging tough now for 23 years, there are too many variables and expenses to convert.

Where did you get that?! That's what I need.

I'm not 100%, but I THINK the sale of R12 these days is illegal, at least without a license.

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I ordered mine as a kit from rockauto. Came with accumulator, compressor, orings, and valve. $191 to my door.

 

The 'kit' is listed right under compressor listing.

Hey jeep driver when you bought this kit did you have to change anything over? Or did you use the old r12 system or the r134?

Any hoses?

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That's another concern of mine... I've heard R134a will leak through the old R12 hoses, but information on whether that's really a valid concern is hit and miss.  Someone here actually have any knowledge on this?  I'm about to order the RockAuto kit, but if need be, I'll order new hoses.  But, with that said, would new hoses do the trick if they're still designed for R12 or have they updated the hoses to be R134a compatible?

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I ordered mine as a kit from rockauto. Came with accumulator, compressor, orings, and valve. $191 to my door.

 

The 'kit' is listed right under compressor listing.

Hey jeep driver when you bought this kit did you have to change anything over? Or did you use the old r12 system or the r134?

Any hoses?

 

It will come as a 134a kit and the compressor is labeled as such.

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That's another concern of mine... I've heard R134a will leak through the old R12 hoses, but information on whether that's really a valid concern is hit and miss.  Someone here actually have any knowledge on this?  I'm about to order the RockAuto kit, but if need be, I'll order new hoses.  But, with that said, would new hoses do the trick if they're still designed for R12 or have they updated the hoses to be R134a compatible?

I called JeepAir last week as their site does not list the hoses for the 2.5

 

They told me that the hose deal is all BS and to blow out the hoses with compressed air and reuse them.

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I called JeepAir last week as their site does not list the hoses for the 2.5

 

They told me that the hose deal is all BS and to blow out the hoses with compressed air and reuse them.

 

Well that's good to know.  I read that you can flush it out with some brake cleaner and then blow it out with compressed air.  Would you recommend doing it that way, or no go on the brake cleaner?

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