A/C whats the difference?

[ftpiercecracker1]

Trying to get my a/c pieced back together and I'm wondering how i should go about this.  The truck still has the old Renix pressure switch plug, evaporator, and expansion valve block that goes on the engine side firewall.

 

I'm wondering how much i can mix and match parts. The main one being the orifice tube used in newer jeeps (r134a) and the expansion block (r12)

 

Whats the difference? 

 

Same for compressors are they all created equal?

 

What about dryer/reciever vs accumulator?

 

Also any idea if i can use flexible hydraulic lines as a/c lines? Soldered copper? Alternatives? I need custom lines because of my alternator/ compressor setup.

[MuddFoot]

If there's an expansion block there's no orifice tube that's a Ford thing. Everything that I used on my 1987 was off of a 95 XJ off of RockAuto and ryc compressor. Anybody that makes hydraulic lines should be able to make you air conditioning lines also. I suggest you take a picture or great measurements to be able to make it exactly how it needs to be so it doesn't rub on anything. Definitely order a new h block for r134 and if you're going that far I hope you change the evaporator coil and the heater coil while you're at it. if you don't you will regret it.

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[MuddFoot]

Also r12 and r134 operate at different pressures. Meaning that we're r12 on the low side would operate between 35 and 45 r134 needs to operate between 45 in 55 PSI unless you have a temperature chart on your gauges. I'm an HVAC, refrigeration technician and electrician.

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[scguy]

Another thing, if you're using R134a in R12 components, use 80% of the R12 refrigerant charge spec.

[AZJeff]

10 hours ago, ftpiercecracker1 said:

Trying to get my a/c pieced back together and I'm wondering how i should go about this.  The truck still has the old Renix pressure switch plug, evaporator, and expansion valve block that goes on the engine side firewall.

 

I'm wondering how much i can mix and match parts. The main one being the orifice tube used in newer jeeps (r134a) and the expansion block (r12)

 

Whats the difference? 

 

Same for compressors are they all created equal?

 

What about dryer/reciever vs accumulator?

 

Also any idea if i can use flexible hydraulic lines as a/c lines? Soldered copper? Alternatives? I need custom lines because of my alternator/ compressor setup.

Others have talked about the expansion process, but I will address your other questions:

 

You will need to acquire an evaporator and a compressor intended for use with R134a, if that is the refrigerant you have chosen.  R134a is not as efficient as the old R12, and so components were resized when the switch over was made.   Likewise, your receiver/drier will need to be R134a sized.

 

You cannnot use hydraulic hoses for refrigerant lines.  The refrigerant molecules are MUCH smaller than oil molecules, and will litterally escape through hoses that don't have the proper barrier layer in them as would a true refrigerant hose.   There are shops out there that will make custom refrigerant hoses, you will just need to search for one.

[Minuit]

You'll want the expansion valve matched to whatever refrigerant you're using. R-134a XV for R-134a use. All pre-97 XJs use systems with the same basic operating principle, although the parts do change a bit.

 

In 1994 they switched from R-12 to R-134a. The pressure switch changed, receiver-drier changed, the expansion valve changed, the compressor technically changed but remained cross compatible, and there may have been some changes to the lines at the same time. The condenser did not change, and that really kneecapped the stock R134a system's performance since R-134a isn't as good a refrigerant as R-12. I strongly suggest using a parallel-flow condenser. I suggest using R-134a for environmental, cost, and parts availability reasons despite this.

 

All of our Jeeps use a receiver-drier and expansion valve instead of an accumulator and orifice tube. That's better anyway. Buy a new receiver drier and make it the last thing you install. Pull the plugs on it right before you button up the system. It must not be exposed to open air for any longer than strictly necessary.

 

Renix 4.0 used an SD508 compressor in an ear mount configuration. HO used an SD709 compressor in a direct mount configuration. Brackets are therefore different. The SD709 compressor has roughly 10% larger displacement.

 

The job MUST BE DONE CLEANLY. Keep your hands clean when working on the A/C components and do not allow any dirt to get inside the system in any way.

 

There's no special magic to A/C lines other than the specific type of hose used. It's called "barrier hose". Just let the guy know it's an A/C hose and he should know what to do. If not, find a guy who specializes in A/C hoses. All of the factory hoses use crimped-on hard fittings at connections.

 

Tools needed for a successful job will be a set of manifold gauges, vacuum pump, HNBR o-ring assortment and an R-134a can tap (or R-12 can tap if you decide to go that way) at the bare minimum. If you have access to a dry nitrogen cylinder it will make for a more accurate leak check before you add refrigerant.

 

This isn't all you need to know but should get you started on choosing parts. I don't think any certain way is better than any other for most uses, and you can have a good working system with pretty much whatever configuration of parts you pick. There are things about the stock Jeep system that do not impress me, so I'll be doing a semi-custom build on my 91 soon, but the stock parts will do most people just fine.

[ghetdjc320]

I posted some info in the diy section about upgrading to the newer style plate and fin evaporator if you want to upgrade everything. I’ve never experienced better ac now in any vehicle, even on max the air is freezing and that’s with Guam weather. 

[ftpiercecracker1]

5 hours ago, ghetdjc320 said:

I posted some info in the diy section about upgrading to the newer style plate and fin evaporator if you want to upgrade everything. I’ve never experienced better ac now in any vehicle, even on max the air is freezing and that’s with Guam weather. 

 

Searched DIY section, couldn't find it. Link?

 

 

 

 

So ignore orifice tube/accumulator.

 

Get new expansion block, why though? Isnt it just a block of metal with two holes? One that is adjusted by a thermostat? I imagine it would be pretty simple to clean/test that right?

 

Reciever dryer, yes, not going to argue here.

 

and evaporator/heat core. I understand the thought process, but mine doesnt leak. I've had the a/c going a couple times in years past. My truck is just a mud toy, totally gutted and ive mastered pulling the dash so its not a big deal if it goes out. Plus i can save a few bucks

 

If i do buy a new one, for what year? The dash changed in 2000? So will i have to stick with pre 2000 parts? Same for condenser? Pre 2000?

 

My truck is a Renix 1990. I can and will cut/splice new connectors electrical or otherwise if it means upgrading to a newer system. The problem is, aren't newer jeeps' a/c controlled by the PCM/ECU vs the renix pressure swithes and thermo resistor thingys?

 

My compressor is used, but a newer variant (134a) It spins freely/quietly and the electro clutch works and it makes pressure when engaged. Are there any further tests?

 

Has anyone considered running propane as their refrigerant? 

[ghetdjc320]

Here is the thread: 

Just ignore all the naysayers And read my last few posts in that thread 😂. Most were saying it wouldn’t work or wouldn’t work well but it actually works much better. Just get plenty of 1x1” foam strips so you can insulate everything and fill in any gaps around the evaporator. And don’t get your ac lines made until you install the evaporator and expansion valve. The new style sets away from the firewall further than oem. The condenser I used is a four seasons one from rock auto for a 91 xj

 

[MuddFoot]

Same here ordered from RockAuto. The h block that you think is just a tube of metal is the metering device that allows the freon to do temperature change so make it so it's cold in your vehicle. R12 runs at different pressures than r134 you can do what you want it will perform better with the right h block. It is illegal to run propane as a refrigerant in anything that is charged greater than 5 ounces in the U.S. there is refrigerant that is deprived from propane but it is missing the explosive molecules. It's an engineered product not propane from Lowe's.

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[ftpiercecracker1]

21 hours ago, ghetdjc320 said:

Here is the thread: 

Just ignore all the naysayers And read my last few posts in that thread 😂. Most were saying it wouldn’t work or wouldn’t work well but it actually works much better. Just get plenty of 1x1” foam strips so you can insulate everything and fill in any gaps around the evaporator. And don’t get your ac lines made until you install the evaporator and expansion valve. The new style sets away from the firewall further than oem. The condenser I used is a four seasons one from rock auto for a 91 xj

 

 

I am currently looking into this. I want to know more about the differences between the evap core styles (fin plate vs tube whatever)

 

So you used an older (pre 97) style condenser, but and newer (post 97) evaporator. 

 

What about the compressor? Are the fittings the same across the years?

 

 

 

 

 

14 hours ago, MuddFoot said:

Same here ordered from RockAuto. The h block that you think is just a tube of metal is the metering device that allows the freon to do temperature change so make it so it's cold in your vehicle. R12 runs at different pressures than r134 you can do what you want it will perform better with the right h block. It is illegal to run propane as a refrigerant in anything that is charged greater than 5 ounces in the U.S. there is refrigerant that is deprived from propane but it is missing the explosive molecules. It's an engineered product not propane from Lowe's.

Sent from my Z982 using Tapatalk
 

 

 

Ok so there are different blocks for the two different refrigerants 

[ghetdjc320]

Old style is tube and fin. Plate and fin is a newer design and provides more surface area for better cooling. Everything else is for my 91MJ. Fittings aren’t really a big deal since your making your own lines anyways.

[ftpiercecracker1]

9 minutes ago, ghetdjc320 said:

Old style is tube and fin. Plate and fin is a newer design and provides more surface area for better cooling. Everything else is for my 91MJ. Fittings aren’t really a big deal since your making your own lines anyways.

 

 

The newer 97+ system uses push to connect fitting with clips. The old system uses threaded fittings.

 

How did you adapt the newer evap core to the older fittings??

 

There is no way to attach the old expansion block to it?

 

Are you using an orifice tube instead?

 

I want to use the fancy new plate/fin design but i don't know how it could be done without replacing the entire system.

[ghetdjc320]

23 minutes ago, ftpiercecracker1 said:

 

 

The newer 97+ system uses push to connect fitting with clips. The old system uses threaded fittings.

 

How did you adapt the newer evap core to the older fittings??

 

There is no way to attach the old expansion block to it?

 

Are you using an orifice tube instead?

 

I want to use the fancy new plate/fin design but i don't know how it could be done without replacing the entire system.

Jump on rock auto and grab an expansion valve and evaporator for a 91 xj. You can’t hardly find the tube and fin design anymore

[ghetdjc320]

Four season part number 54812 and 38880 are the two parts I used 

[ftpiercecracker1]

Ok, cool. Looks just like the post 97 evap core but with threaded fittings.

 

So pretty much everything can be pre 97?

 

 

I wonder why the condensers arent plate and fin style. 

 

Also someone mentioned i should get a parallel flow condenser. It looks like they are all parallel, although they don't say it explicitly. 

[Minuit]

What I call a "parallel flow" is what @ghetdjc320 calls "plate and fin". The refrigerant flows evenly from one side to the other in separate channels, rather than back and forth. Roughly a 20% to 30% efficiency improvement. APDI part number 7014173 is a direct fit and uses the threaded line connections. Almost all aftermarket reproduction condensers are "serpentine" tube and fin condensers. The APDI is the only one I'm aware of that is different from the original design.

 

I do not know if you can install the aftermarket parallel flow evaporators in a 1990 heater box. If you can, that would be a worthwhile upgrade - I cannot confirm personally but @ghetdjc320 had good results and managed to retain the evaporator probe, which is essential to a properly functioning system.

 

If your compressor spins freely without resistance, noise, or binding, that's about the best you can hope for. I'd rather have a used compressor that spins smoothly over a new reman. I am no fan of the Sanden A/C compressors that Jeep used, but if it works it works.

[ghetdjc320]

Thanks @Minuit for the clarification. That is the condenser part number I used too

[ftpiercecracker1]

Ok perfect. Thanks for the part number. 

 

So this Condenser (APDI 7014173) and this Evap core (UAC EV4178PFXC)

 

Next is the expansion block and reciever dryer.

 

Based on what ive seen, 1991 dryer does not have a socket for the plug that is on mine. Which i assume has something to do with the pressure switch. 

 

Compressor oil, ether or mineral?

 

 

[Minuit]

For a primarily new system using R-134a and an SD709 compressor, PAG 100. No additives or stop leak crap. The only thing in your system should be refrigerant and oil. Ester oil is generally used in retrofits, but you're building a new system. Drain the existing oil from the compressor and add roughly 6 to 7 oz of oil to the system. You can put it all in the compressor, half in the compressor and half in the condenser, or whatever. Just make sure there is some oil in the compressor when you start the system. If you add the entire charge to the compressor, rotate the compressor 10 full revolutions right before beginning the charge.

 

Mineral oil will not be carried through the system by R-134a. It is for R-12 or R-12 compatible refrigerants only.

 

As a side note - for a custom system, it'll be damn impossible to tell you HOW MUCH refrigerant/oil you will need. That is calculated based on the internal system volume and was done when the system was designed. You are deviating from the factory setup so I cannot tell you an exact amount of refrigerant or oil.

[ftpiercecracker1]

On 4/26/2020 at 11:29 PM, Minuit said:

For a primarily new system using R-134a and an SD709 compressor, PAG 100. No additives or stop leak crap. The only thing in your system should be refrigerant and oil. Ester oil is generally used in retrofits, but you're building a new system. Drain the existing oil from the compressor and add roughly 6 to 7 oz of oil to the system. You can put it all in the compressor, half in the compressor and half in the condenser, or whatever. Just make sure there is some oil in the compressor when you start the system. If you add the entire charge to the compressor, rotate the compressor 10 full revolutions right before beginning the charge.

 

Mineral oil will not be carried through the system by R-134a. It is for R-12 or R-12 compatible refrigerants only.

 

As a side note - for a custom system, it'll be damn impossible to tell you HOW MUCH refrigerant/oil you will need. That is calculated based on the internal system volume and was done when the system was designed. You are deviating from the factory setup so I cannot tell you an exact amount of refrigerant or oil.

 

 

Thanks, got it PAG 100

 

As far how much refrigerant i imagine the pressures will dictate when the system has a full charge.

 

 

 

Any thoughts on the pressure switch? 

[ghetdjc320]

The evaporator and condenser we referenced along with the oem dryer and a 709 compressor took 1.2lbs and works perfectly at that amount for my system

[Minuit]

11 hours ago, ftpiercecracker1 said:

 

 

Thanks, got it PAG 100

 

As far how much refrigerant i imagine the pressures will dictate when the system has a full charge.

 

 

 

Any thoughts on the pressure switch? 

Charging by pressure is not ideal but it is probably what you will have to do. For reference, the '96 system takes 2 lbs of R-134a. The earlier systems took something like 44 oz of R-12. Parallel flow condensers and evaporators have lower capacity than the original style, so your charge amount probably end up somewhere between 1 and 2 lb.

 

It's my opinion that the original R-12 pressure switch will probably be ok, since in normal operation its job is basically "yep, we have refrigerant present in the system. It is not dangerous to engage the clutch" and cycling is primarily done by the probe in the evaporator unless you have a leak and the system runs dry or something causes an excessively high pressure in the system.

 

The pressure switch for a 94-96 XJ is calibrated for R-134a. The plug is different. I do not know if it will fit the earlier receiver-drier. I do not know if the later receiver-drier that goes with it will fit your truck.

[ftpiercecracker1]

1 hour ago, Minuit said:

Charging by pressure is not ideal but it is probably what you will have to do. For reference, the '96 system takes 2 lbs of R-134a. The earlier systems took something like 44 oz of R-12. Parallel flow condensers and evaporators have lower capacity than the original style, so your charge amount probably end up somewhere between 1 and 2 lb.

 

It's my opinion that the original R-12 pressure switch will probably be ok, since in normal operation its job is basically "yep, we have refrigerant present in the system. It is not dangerous to engage the clutch" and cycling is primarily done by the probe in the evaporator unless you have a leak and the system runs dry or something causes an excessively high pressure in the system.

 

The pressure switch for a 94-96 XJ is calibrated for R-134a. The plug is different. I do not know if it will fit the earlier receiver-drier. I do not know if the later receiver-drier that goes with it will fit your truck.

 

 

There is no high pressure cut off?

 

Keeping the old plug would require using the old dryer.

Can i just cut and splice the newer plug on in order to use the newer dryer?

 

What year? Would it also be 1991?

 

So that would be a 1991 exp block and dryer?

[Minuit]

4 minutes ago, ftpiercecracker1 said:

 

 

There is no high pressure cut off?

 

Keeping the old plug would require using the old dryer.

Can i just cut and splice the newer plug on in order to use the newer dryer?

 

What year? Would it also be 1991?

 

So that would be a 1991 exp block and dryer?

The pressure switch is a dual high-low cutoff switch. The receiver drier is on the high side of the system. The pressure switch changed in 1994 with the switch to R-134a.

 

The receiver drier design is different between Renix and HO. If you try to put a newer model receiver drier in, I do not know if the lines will connect and I don't know if it'll even fit the truck. I would just buy a new receiver drier for your year. Yes, you can splice the plug if you want to try using the new design receiver drier. I can't tell you if it will fit.