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Compressor Differences between R12 and R134?

IslanderOffRoad

IslanderOffRoad

NAXJA Forum User
NAXJA Member
Location
Houston, Tx
94 Cherokee, one of the last ones with R12 for the A/C. Had the system converted to R134, and 2 months later the compressor siezed. Was looking at picking up a working used compressor from another member here, its from a 95 Cherokee that came with R134.

Is there any reason this compressor wouldn't bolt right in to my Jeep?

I figure I can get the local a/c guy to evac the current siezed one, and then I'll swap the parts, and he can refill it.
 
It's been a while... All I do know is 134 need higher pressures to work. so depending on where the changes are in the system you may have to remove some peices of your conversion so the pressures aren't too high. Also what about mounting. is that the same?
 
wolfpackjeeper said:
I have been looking at this too, I think it would work depending on the hoses
Click to expand...


The compressors are different on the outside but serve the same purpose on both years.

The Main change in the system is the expansion valve. (On firewall where A/C lines go into cab.)

I recommend replacing the expansion valve when you do the swap.
They plug all the time. ESP when a compressor has frozen.
This is the part that controls the system pressures. Make sure to get the R12 EXP valve if that is the way you go.

Also, if you can have a dryer installed, it would be a good Idea.
It will filter out any contaminates and ensure no moisture is in the system.


XJR
 
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R134a compressors are built to run a higher head pressure (R134a has a higher working pressure than R12) and the lubricants are incompatible. If you're getting a R134a compressor, might as well finish the job - replace the receiver/dryer, flush everything else, and convert to R134a anyhow.
 
they are the same i have converted alot of them it is a good idea to replace the accum. and while you have it open use brakes parts cleaner to clean out all the lines to remove the old r12 oil then use air to blow it out install the new accum.pulla vaccuum on the system and recharge with 134a oil and refrigerant.
 
AN R12 COMPRESSOR WILL RUN AN R134 SYSTEM.

I have done the conversion myself and it works fine.

it was colder then the R12. Since R12 is more efficient then R134a, I suspect the R12 system was never really working well and might even have been low.

Ever had snow flakes blow at your face from the AC when its 90 outside?
Its nice!
 
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XJRubicon said:
AN R12 COMPRESSOR WILL RUN AN R134 SYSTEM.

I have done the conversion myself and it works fine.

it was colder then the R12.

Ever had snow flakes blow at your face from then AC when its 90 outside?
Its nice!
Click to expand...

Yes, it will (I did the conversion as well.)

However, R134 runs at a marginally higher head pressure, and you've got better odds of blowing a compressor head gasket or piston rings... Forewarned is forearmed.
 
Compressors from 91-96 all have the same external physical characteristics (mounting, line placement, etc.). Lines were the same in 91-93 and changed in 94-96 with the switch to R-134a.
 
5-90 said:
Yes, it will (I did the conversion as well.)

However, R134 runs at a marginally higher head pressure, and you've got better odds of blowing a compressor head gasket or piston rings... Forewarned is forearmed.
Click to expand...

hahahahahaha

You crack me up man. seriously.

I have NEVER seen an automotive compressor blow a head gasket.

Hell, the only head gasket I have replaced on a AC compressor was on a 10 ton York on an office building that was 15 years old.

Book smart is not street smart.

... and don't even try the whole front seal thing... its the same part.

XJR
 
XJRubicon said:
hahahahahaha

You crack me up man. seriously.

I have NEVER seen an automotive compressor blow a head gasket.

Hell, the only head gasket I have replaced on a AC compressor was on a 10 ton York on an office building that was 15 years old.

Book smart is not street smart.

... and don't even try the whole front seal thing... its the same part.

XJR
Click to expand...

I'm going by what I've been told by aircon techs - I'm more into engines and transmissions, myself.

I have confirmed that R134a does run somewhat higher head pressures (I don't recall the exact different - 8-10% wants to come to mind,) but I'll toss it out as a warning until it's proven, to my satisfaction, that it's not a concern. I've taken apart a couple of SD505's - I know the head gasket is pretty stout, so it's probably not a worry for us. However, it hasn't been proven to me that I shouldn't worry about it, so I'll keep it as a tickle in the back of my mind.

As far as the piston rings - it's an axial compressor driven by a swash plate - so you've got pistons as well. Having seen axial compressors with blown piston rings, I'm quite sure that's a point of failure that can be accelerated as well.
 
sweet, so it looks like the dd is getting the extra compressor we have laying around as well as a new reciever drier(1996) and oriface tube(1992) and probably new lines just for the fun of it.
 
XJRubicon said:
hahahahahaha

You crack me up man. seriously.

I have NEVER seen an automotive compressor blow a head gasket.

Hell, the only head gasket I have replaced on a AC compressor was on a 10 ton York on an office building that was 15 years old.

Book smart is not street smart.

... and don't even try the whole front seal thing... its the same part.

XJR
Click to expand...

Let me crack you up a little more, both the Sanden and the York do have heads. I'd likely listen to what 5-90 had to say, before taking advice from a tire and rim salesman or is it compressor expert? Most of the answers are in the books somewhere, some people waste there time researching, others waste there time talking trash.
The HPRV (Sanden) is different for freon 12 and 134a, there is a chance it may pop before the 134a reaches operating pressure/temperature. Or worse yet something else breaks.
In your recommendations, I sure didn't notice any reference to hooking up a vacuum pump and removing as much air as possible. If you leave much air in there, it's sure to run the head pressures up and pop the HPRV if your lucky.
My only qualification for commenting, is I've likely fixed 18,000 refrigeration systems, about 2 a day for as long as you've been alive. Though of course I don't claim to be a know it all, especially in automotive systems.
 
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8Mud said:
Let me crack you up a little more both the Sanden and the York do have heads. I was working on compressors thirty years before you were popped out of the oven. I'd likely listen to what 5-90 had to say, before taking advice from a tire and rim salesman or is it compressor expert? Most of the answers are in the books somewhere, some people waste there time researching, others waste there time talking trash.
The HPVR valve (Sanden) is different for freon 12 and 134a, there is a chance it may pop before the 134a reaches operating pressure/temperature. Or worse yet something else break.
Click to expand...


I never said they don't have heads, I said I have never seen one blow.
Front seal, sure, seize up because of the rings, sure, but never blow a head gasket.

I just can't understand why you think an increase in pressure of 8-10%, when its already 350psi, is going to cause a failure.

What do you think happens when the expansion valve is clogged? The head pressure skyrockets! WAY over R134a pressures. Yet STILL the head gasket does not fail. EVER.

You guys don't even know what you are talking about.
My father was a HVAC guy for 35 years and I almost followed in his footsteps. I have been around refrigeration my entire life.

Show me proof that the head gasket will fail on a R12 compressor running R134a and I will stand corrected.


But the fact of the matter is it will never happen.

Mine has been running strong since 03' How's that for proof?

...And did you just call me a tire salesman?
Your ignorance is showing....


XJR
 
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HVAC is not the same as auto...........I just do this for a living..

Refrigeration, walk ins? Is this the type you are talking about..??? Stop doing them a long time ago.... Takes all day to get them running right.... Low temp work sucks
 
XJRubicon said:
I never said they don't have heads, I said I have never seen one blow.
Front seal, sure, seize up because of the rings, sure, but never blow a head gasket.

I just can't understand why you think an increase in pressure of 8-10%, when its already 350psi, is going to cause a failure.

What do you think happens when the expansion valve is clogged? The head pressure skyrockets! WAY over R134a pressures. Yet STILL the head gasket does not fail. EVER.

You guys don't even know what you are talking about.
My father was a HVAC guy for 35 years and I almost followed in his footsteps. I have been around refrigeration my entire life.

Show me proof that the head gasket will fail on a R12 compressor running R134a and I will stand corrected.

But the fact of the matter is it will never happen.

...And did you just call me a tire salesman?
You're ignorance is showing....


XJR
Click to expand...

You are right, blowing smoke up someones rear unnecessarily is ignorant. There is a HPRV (high pressure relief valve) in many of the Sandens. If it fails and the pressures go way up, because of air or valve failure, some thing is going to spring a leak and never is a long time.
Expansion valves have a screen filter in them (that can be cleaned) and they rarely fail. In the first page of the troubleshooting manual for most types of expansion valves, they say the most common cause of failure is the hammer. Second most common cause is moisture, though the screens occaisonally get clogged with debris.
Maybe you should go back and watch some more.
I've seen various automotive compressors spring leaks in various places, I've seen them seep in the rear.
Your entire life is less than half of mine. Come back in 30 years and tell me it will "never" happen.
 
scottmcneal said:
HVAC is not the same as auto...........I just do this for a living..

Refrigeration, walk ins? Is this the type you are talking about..??? Stop doing them a long time ago.... Takes all day to get them running right.... Low temp work sucks
Click to expand...


No, Do you realize how big a 10 ton AC unit is?

Our old house was 2500 square feet and only needs a two and a half ton.

That would be one huge cooler man.

Not the same as auto? Why because different refrigerants are used?

I don't think so. Automotive AC is only a smaller system.

Sure there are slight differences but the basic theory on how the systems work is Identical.

I have done a lot of automotive AC work over the years with my Father.
I almost went for my license but I did not want to be in the horrible pain he was always in from being on 130 degrees rooftops in the summer and 40 below in the winter. It played hell with him.

I will say i again, specs on paper mean nothing in the real world. This isn't building a house here.

XJR
 
8Mud said:
You are right, blowing smoke up someones rear unnecessarily is ignorant. There is a HPRV (high pressure relief valve) in many of the Sandens. If it fails and the pressures go way up, because of air or valve failure, some thing is going to spring a leak and never is a long time.
Expansion valves have a screen filter in them (that can be cleaned) and they rarely fail. In the first page of the troubleshooting manual for most types of expansion valves, they say the most common cause of failure is the hammer. Second most common cause is moisture, though the screens occaisonally get clogged with debris.
Maybe you should go back and watch some more.
I've seen various automotive compressors spring leaks in various places, I've seen them seep in the rear.
Your entire life is less than half of mine. Come back in 30 years and tell me it will "never" happen.
Click to expand...

You are a real know it all aren't you?

No need to take an attitude old man.

Does it annoy you that I proved you wrong or whats the deal?

You wanna come feel my AC?


ChipsXJ said:
...In the mean time he evacuated my 93 system to 'top off' my r12 but could not recharge it..another 100.00. advised that my expansion valve was clogged.....
Click to expand...

Yeah... that never happens...
 
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XJRubicon said:
You are a real know it all aren't you?

No need to take an attitude old man.

Does it annoy you that I proved you wrong or whats the deal?

You wanna come feel my AC?




Yeah... that never happens...
Click to expand...

In reverse order.

If I go pull one out of the junk yard,, will you eat it?

Your are a seriously ignorant little plick aren't you? No I don't want to come feel your AC (asscünt?).

I didn't notice you proving me wrong about anything, though you did do a pretty good job showing your arse.

Attitude, sorry can't help myself, self important little plicks always make me want to slap em up side the head.

Know it all, not hardly, but even if I'm half as smart as you are, I've had more than twice as long to get it right.
 
The air is thin where he lives.... 90 degress, oh my god..... it cools down to that at night here during the summer.... Come sit on a roof here, then go get your burned butt fix..... Thats my 2 cents
 
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