Warren99 Posted January 17, 2023 Author Share Posted January 17, 2023 I still haven't decided yet but we will see. In other news, funnily enough I might be able to get the evap core out without disconnecting it by cutting the fire wall. I'm dealing with a completely stripped engine bay so it may not be that hard. Link to comment Share on other sites More sharing options...
AZJeff Posted January 17, 2023 Share Posted January 17, 2023 1 hour ago, Pete M said: Technically the only things you need for switching are the 134 ports that come in the kit linked below. BUT a new accumulator is very nice. as is new orings and a 134 specific expansion valve. I'm currently redoing a friend's truck and converting as I go. r-12 has real value these days to guys stuck using it. 134 is dirt cheap. convert while you can and never look back. https://www.amazon.com/Replacement-Expansion-Valve-Compatible-56003173/dp/B0987GKXZS/ https://www.amazon.com/Mudder-VA-LH11-Retrofit-Conversion-Adapter/dp/B07W91FT8T Yeah, you don't want to use R12 anymore unless you have NO other choice. R12 is HORRIBLY expensive, (typically between $30 and $50 for a 12 ounce can that most DIY guys would use). Also, you cannot buy R12 at normal retail outlets. You have to resort to the "gray" market on eBay. On the other hand, R134a is about $12 for a 12 ounce can at almost any auto parts store. Since you are already planning on disassembling your AC system to work on the heater box, the differential cost to do the conversion is going to be: 1. the two R134a adapter fittings that attach to existing R12 filling ports on the high and low pressure lines. (Figure this is less than $20) 2. the appropriate amount R134a compatible refrigerant oil (Again, that's $10) All the other things I described (accumulator and o-rings) you are going to need REGARDLESS of whether you convert to the more modern refrigerant. So if you spend about $30 up front, you will spend less than $24 to fill your system with R134a. (Assuming two 12 ounce cans to fill the system) If you keep with the R12, you will spend $80 to fill your system with R12. (again assuming two 12 ounce cans to fill the system) And if a leak shows up during your fill, then you are back to spending much more for any further refrigerant you will need if you stay with R12. As I Pete said, it makes little sense, economically, to stay with R12 on an MJ. Link to comment Share on other sites More sharing options...
AZJeff Posted January 17, 2023 Share Posted January 17, 2023 19 minutes ago, Warren99 said: I still haven't decided yet but we will see. In other news, funnily enough I might be able to get the evap core out without disconnecting it by cutting the fire wall. I'm dealing with a completely stripped engine bay so it may not be that hard. That is fine, buy how do you intend to get the same evaporator into the "good" heater box in your vehicle? I assume you are not planning on cutting THAT firewall, are you? Link to comment Share on other sites More sharing options...
Warren99 Posted January 17, 2023 Author Share Posted January 17, 2023 11 minutes ago, AZJeff said: That is fine, buy how do you intend to get the same evaporator into the "good" heater box in your vehicle? I assume you are not planning on cutting THAT firewall, are you? Oh no I wasn't gonna attempt that lol, just figured if I could spend 15 min of cutting the firewall to get it all out without cracking the lines loose then why not. Also yea I probably will just do the r134a swap this time around then. So I'll need a new accumulator, evaporator and o-rings. That is all I'll need to work in combination with my r12 pump and condensor etc? Lastly, if I do that I'm obviously just gonna get a brand new evaporator since its deep in the dash along with the heater core, but would everything else be fine enough to just get from a junk yard? Link to comment Share on other sites More sharing options...
AZJeff Posted January 18, 2023 Share Posted January 18, 2023 19 hours ago, Warren99 said: Oh no I wasn't gonna attempt that lol, just figured if I could spend 15 min of cutting the firewall to get it all out without cracking the lines loose then why not. Also yea I probably will just do the r134a swap this time around then. So I'll need a new accumulator, evaporator and o-rings. That is all I'll need to work in combination with my r12 pump and condensor etc? Lastly, if I do that I'm obviously just gonna get a brand new evaporator since its deep in the dash along with the heater core, but would everything else be fine enough to just get from a junk yard? Keep in mind that if you are pulling parts from a junkyard, those parts are probably close to the same age as the ones currently in your vehicle. That means any refrigerant hoses and the blower motor are in a donor vehicle are aged. If I was re-doing the AC system in your vehicle, I would inspect my existing hoses for any signs of cracking or chafing, and replace with new as needed. For reasons I explain below, I would replace the blower motor and the blower motor resistor with NEW parts while I was at it. (The motors tend to draw more current as they age, and this taxes the blower motor switch more heavily, and possibly can cause it to MELT. There have been photos of this phenomenon on this board before.) Link to comment Share on other sites More sharing options...
Warren99 Posted January 18, 2023 Author Share Posted January 18, 2023 Alright I'll do those and inspect everything else. I think the only thing I will replace a/c wise will be the evaporator, unless I need to get a brand new accumulator as well. Link to comment Share on other sites More sharing options...
Warren99 Posted January 18, 2023 Author Share Posted January 18, 2023 A/C is out of the parts truck. I figured I'd check if there actually was anything in the system because for the short time that I did have the engine running while it was still in, the compressor wouldn't even kick on, and sure enough there was zero pressure from the valves at the compressor, so I just disconnected the lines before the firewall and removed it. Link to comment Share on other sites More sharing options...
AZJeff Posted January 19, 2023 Share Posted January 19, 2023 9 hours ago, Warren99 said: Alright I'll do those and inspect everything else. I think the only thing I will replace a/c wise will be the evaporator, unless I need to get a brand new accumulator as well. It is considered good practice to replace the accumulator whenever the system is open to the atmosphere for any length of time, as yours will be. The accumulator contains a desiccant to trap any moisture left in the system, and when left open for long periods, that desiccant is trashed by that uncontrolled exposure to moisture. Accumulators are not very expensive, and a new one will insure best AC performance. Link to comment Share on other sites More sharing options...
Warren99 Posted January 19, 2023 Author Share Posted January 19, 2023 Ok I'll get a new accumulator too Link to comment Share on other sites More sharing options...
AZJeff Posted January 19, 2023 Share Posted January 19, 2023 On 1/17/2023 at 2:49 PM, jdog said: You might also check to see what his gauges are, different refrigerants take different gauges The guages will be the same. What will be different will be the fittings on the hoses that connect to the fill ports on the vehicle. New fittings can be obtained to attach to the existing hoses. A new can tap valve is needed to connect a R134a can to the fill hose, and any auto parts store will have that. Link to comment Share on other sites More sharing options...
jdog Posted January 19, 2023 Share Posted January 19, 2023 2 hours ago, AZJeff said: The guages will be the same. What will be different will be the fittings on the hoses that connect to the fill ports on the vehicle. New fittings can be obtained to attach to the existing hoses. A new can tap valve is needed to connect a R134a can to the fill hose, and any auto parts store will have that. R12 to r134 to r20/400/500 all are different gauges. Also why contaminate what ever they were using the gauge set previously? Link to comment Share on other sites More sharing options...
AZJeff Posted January 20, 2023 Share Posted January 20, 2023 1 hour ago, jdog said: R12 to r134 to r20/400/500 all are different gauges. Also why contaminate what ever they were using the gauge set previously? If you purge the manifold, contamination is nil. Pressures for R12 and R134a are such that one set of gauges are suitable for both. Link to comment Share on other sites More sharing options...
jdog Posted January 20, 2023 Share Posted January 20, 2023 21 minutes ago, AZJeff said: If you purge the manifold, contamination is nil. Pressures for R12 and R134a are such that one set of gauges are suitable for both. But what gauge set does he have was my question. He says his dad has done it but doesn't state what his gauge set is for. Link to comment Share on other sites More sharing options...
Warren99 Posted January 20, 2023 Author Share Posted January 20, 2023 1 hour ago, jdog said: But what gauge set does he have was my question. He says his dad has done it but doesn't state what his gauge set is for. I think by default the hose ends are for 134a but it has adapters to go onto 12. I know for sure he has used it for both in the past. Link to comment Share on other sites More sharing options...
zomeizter Posted January 20, 2023 Share Posted January 20, 2023 Man this here info is awesome, I've been considering using my rusty 01 xj as a donor for the mj. The only thing stopping that is the xj's slosh box, I despise ATs, sure wish I could find me an NV3550 so the swap could happen... Link to comment Share on other sites More sharing options...
Warren99 Posted January 20, 2023 Author Share Posted January 20, 2023 The NV3550 is the 5 speed in the later generations right? Link to comment Share on other sites More sharing options...
zomeizter Posted January 20, 2023 Share Posted January 20, 2023 36 minutes ago, Warren99 said: The NV3550 is the 5 speed in the later generations right? Yes. Link to comment Share on other sites More sharing options...
Warren99 Posted January 20, 2023 Author Share Posted January 20, 2023 Did they only start in 97? Link to comment Share on other sites More sharing options...
Warren99 Posted January 20, 2023 Author Share Posted January 20, 2023 Nevermind I just looked it up Link to comment Share on other sites More sharing options...
Warren99 Posted March 20, 2023 Author Share Posted March 20, 2023 I have since began tearing apart my actual truck, rather than the parts one which is now gone. I'm at the point of having to remove my hvac box to install my new evap core and heater core. Unfortunately, so far every stud I have touched on the firewall in the engine bay is spinning with the nut. If I put vice grips on(channel locks are too big), they hold still for maybe 1/3 of the way off, but then tighten up again and just slip. If I remove the resevoir and emissions thing off the fender, I can get to most of them a lot easier, and maybe make something else work. -Is there some way to get to the studs from the inside of the truck some how? Or any other easy method? Link to comment Share on other sites More sharing options...
Pete M Posted March 20, 2023 Share Posted March 20, 2023 those studs screw directly into the plastic of the box and so if you turn them, they might just unscrew from said box. it might be mostly free and you're just missing one. Link to comment Share on other sites More sharing options...
Warren99 Posted March 20, 2023 Author Share Posted March 20, 2023 Ah ok. I'll just turn each stud a bunch then and see where it takes me. Link to comment Share on other sites More sharing options...
Pete M Posted March 20, 2023 Share Posted March 20, 2023 it's only like 4 turns to unscrew them. Link to comment Share on other sites More sharing options...
Warren99 Posted March 22, 2023 Author Share Posted March 22, 2023 Got the HVAC off and new heater core + evap core in. Couple of questions tho. -The heater core seemed slightly larger, and didn't come with foam rubber stuff that would keep it from coming into contact with the plastic box. So I peeled as much of the old stuff off the old heater core and tried using it, but then the heater core appeared to be sticking up too high. So I took the rubber stuff back out and I think the core still slightly touched the top but it's not really bulging. Is this an issue? Is it gonna melt the box? -The evap core was different in design(passages are travelling 90 degrees compared to oem, and they are thin and wide, opposed to just being tubes). Despite not having a tap for 2 screws to hold it in place, it still fit nice and snug. The real issue I might have is with the probe thing that slid into the original one. I simply bent it around the side, then stuck it in between the fins. Will it still work properly? And what is it, the blower motor switch or something? I have the whole HVAC box screwed back together. I'm waiting on input on these potential problems before I put it back in the next chance I get. Link to comment Share on other sites More sharing options...
Warren99 Posted March 22, 2023 Author Share Posted March 22, 2023 Here is what the OEM evaporator and heater core look like, with the rubber insulation stuff I was talking about before laying around the heater core. Link to comment Share on other sites More sharing options...
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