88 GW A/C revival and R134a retrofit

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88 GW A/C revival and R134a retrofit

Post by sirrus » Tue Jun 02, 2020 2:40 pm

So summer is here and it is getting less and less comfortable in the Jeep without AC. When I got my waggy AC didn't work and PO didn't know anything about what was wrong with it. First time I tried to turn it on engine died right away - but that was before I even did initial tune up. Now when if I switch it on nothing happens - no air from vents (warm or cold), just some clicking/clunking sound from under the dash. I never worked on AC systems before and knew almost nothing about them, but it was the same for mostly every system on the Jeep. Some online research, reading TSM and asking people helps a lot :D

So here is my plan and I hope that someone with more experience than me would chime in and tell me if I'm not getting something right
  • Sort out electrical issues first. As I understand the blower should turn on no matter what's going on with refrigerant level or compressor. Possible candidates here are blower relay, switches, wiring or just dead blower motor. Looking at pictures online I'm thinking that heater blower motor and AC one are different, am I right? Just thinking ahead if I have to get a new one.
  • Once I have the fan running I also want to check if compressor clutch is getting a signal to turn on. I suppose that with jumping the pressure sensor and unplugging wire to clutch (I don't want to run compressor on empty system) I should see 12V on that bullet connector?
  • Not sure if there are any vacuum actuators on the AC duct, but I'll check that as well
  • I'm pretty sure that system is empty of refrigerant after few years with hoses that look pretty dry-rotten. I can think of couple ways to check that like checking if pressure sensor is closed or open or actually checking the pressure on one of the service ports with a gauge
  • Original system is R12 and I think my best option is to convert to R134a - hoses look like they need replacing anyway, R12 is pricey on eBay and R12 "alternatives" are all flammable gases that I don't want anywhere near engine or passenger compartment. More questions about conversion below.
  • Once I fix the electrical issues, convert the system to R134a and recharge it I should be good, right?
Now more about R134a retrofitting. After searching this forum, ifsja and other places I think I'm getting an idea what I need to get to do it, however there are different opinions everywhere, so I'll appreciate any feedback here:
  • new hoses - mostly because old ones are probably leaking like a sieve anyway. Saw a lot of folks suggesting getting barrier hoses
  • o-rings and other seals - once again, old ones are old and I'll need new ones that are R134 compatible
  • drier - need new one since desiccant is refrigerant specific and I also read that it's a good practice to replace that if system was open
  • oil purge - have to get all mineral oil out before introducing R134 to the system. Some say that just pulling a vacuum for hour or two is enough, some suggest using nitrogen or some special flushing solutions
  • expansion valve - not sure if original is R12-only, but it's not crazy expensive and easy to get
  • condenser - some mentioned that because R134 is less efficient as a refrigerant than R12, replacing stock finned condenser with parallel flow one is a good idea. I never had a vehicle with R12 AC, so I don't know how cold it is compared to modern ones, but I want cold :) Also not sure whether new condenser with fit with stock transmission cooler if I go with ebay kit (linked below)
  • compressor - as my rig is 88 it came with York compressor (no idea about it's condition though). I've read that later years Sanden compressors are more efficient and more R134-friendly (Yorks supposedly are prone to blowing front seal after conversion). Is that so? Should I upgrade to Sanden or leave York?
Having that initial parts list, I looked around for a place to get all of it and found that eBay listing. I saw that seller mentioned here and on ifsja with a good feedback and that kit covers everything from the list above. Does that look like a good option?
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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Sat Jun 06, 2020 7:08 am

https://oljeep.com/
I suggest looking at the wiring diagram at this website, I think your a/c system was used in 86 and newer FSJ's,the "control module" if bad could be hard to find, good luck


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sat Jun 06, 2020 9:33 am

Thanks for input!

So far from studying wiring diagrams, I understand that control module is responsible for turning compressor clutch on/off depending on input from temperature probe (in evaporator housing) and potentiometer in heater/ac control. I suspect that part of system is ok because as I mentioned earlier turning AC on would kill the engine on idle (before tune up) - I think that was due to extra load from AC compressor engaging.

AC blower does not look like it's controlled by that module, so hopefully it's some loose wire or bad blower resistor. BTW I've found AC control modules for sale on eBay for $50. Temperature probe is harder to find, but since it's just a thermistor I think it should be possible to match something else to resistance/temperature table from TSM.

Anyway, I'm going to look at electric side of things with AC today, will report back with what I've found :)

The part that I'm not that confident about is R134 conversion - any advice on the second list in my post? I'd like to start ordering parts soon to get this whole thing going :D
1988 Grand Wagoneer - bone stock (AMC 360, TF727, NP229), slowly turning into reliable and nice daily driver

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Re: 88 GW A/C revival and R134a retrofit

Post by SJTD » Sat Jun 06, 2020 10:21 am

sirrus wrote:
Tue Jun 02, 2020 2:40 pm

Now more about R134a retrofitting. After searching this forum, ifsja and other places I think I'm getting an idea what I need to get to do it, however there are different opinions everywhere, so I'll appreciate any feedback here:
  • new hoses - mostly because old ones are probably leaking like a sieve anyway. Saw a lot of folks suggesting getting barrier hoses
    Yes but I doubt you can get anything else.
  • o-rings and other seals - once again, old ones are old and I'll need new ones that are R134 compatible
    Always replace anyway.
  • drier - need new one since desiccant is refrigerant specific and I also read that it's a good practice to replace that if system was open
    Always want a new drier anyway.
  • oil purge - have to get all mineral oil out before introducing R134 to the system. Some say that just pulling a vacuum for hour or two is enough, some suggest using nitrogen or some special flushing solutions
    Vacuum won't remove the oil, purging leaves some. Need to flush. Ideally you'd remove the evaporator so you can do it well.
  • expansion valve - not sure if original is R12-only, but it's not crazy expensive and easy to get
    Original will be fine. I doubt you can get one specific to 134 anyway.
  • condenser - some mentioned that because R134 is less efficient as a refrigerant than R12, replacing stock finned condenser with parallel flow one is a good idea. I never had a vehicle with R12 AC, so I don't know how cold it is compared to modern ones, but I want cold :) Also not sure whether new condenser with fit with stock transmission cooler if I go with ebay kit (linked below)
    Need to flush the old one. If you have the money I'd replace it.
  • compressor - as my rig is 88 it came with York compressor (no idea about it's condition though). I've read that later years Sanden compressors are more efficient and more R134-friendly (Yorks supposedly are prone to blowing front seal after conversion). Is that so? Should I upgrade to Sanden or leave York?
    Lot of work to flush it, hook it up, charge it to find it's bad. Again, if you can afford it...
Having that initial parts list, I looked around for a place to get all of it and found that eBay listing. I saw that seller mentioned here and on ifsja with a good feedback and that kit covers everything from the list above. Does that look like a good option?
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sat Jun 06, 2020 12:03 pm

OK, so it looks like I need almost everything from my initial list, expansion valve being optional. Not sure about condition of it, so might just get a new one as well. I think I can afford it - goal here is get it working good once and ideally don't have to fix it again and again.

Since I would be getting new everything except evaporator I think it would be easy enough to remove and flush it. At that point should I use the old one or get a new one as well?

About condenser - should I get a parallel flow or go with factory one? My biggest concern here is fitment (especially with stock tranny cooler) as I'm very limited in fabricating new mounts.

And the last question for now - what are good sources for parts that I need? So far I've found that kit on eBay, and BJs and TGW sell most of them - any other suggestions?
1988 Grand Wagoneer - bone stock (AMC 360, TF727, NP229), slowly turning into reliable and nice daily driver

Relay modules and other parts for sale

How to clean electric switches (power windows, locks, seats)


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sat Jun 06, 2020 8:32 pm

Figured out why AC blower was not working - blower itself is rusted and barely moves and thermal fuse in blower resistor is blown. Fortunately, both are available and not that expensive.

Compressor clutch is working same as AC control module. Thermistor in evaporator is also looking good and resistance somewhat matches what it should be. Low pressure sensor was closed (as it would with charged system), so out of curiosity I decided to check compressor on a running engine. Disconnected clutch wire, turned AC on, got back to engine bay and reconnected clutch wire.

And then I saw short burst of bubbles through sight glass! After few seconds compressor turned off, I checked AC duct around evaporator and it was cold. So turns out I have a fully functional AC minus blower motor and resistor! Never expected that, my Jeep is full of surprises for sure :)
1988 Grand Wagoneer - bone stock (AMC 360, TF727, NP229), slowly turning into reliable and nice daily driver

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Re: 88 GW A/C revival and R134a retrofit

Post by SJTD » Sat Jun 06, 2020 10:19 pm

You say the pump turned off. Did you disconnect it or did it shut off on its own?

Might still be low on refrigerant but I'd say if it aint broke...
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sat Jun 06, 2020 10:23 pm

Shut off on its own after 30 seconds of working. Low pressure switch was still closed, so pressure should be ok. My theory is that without airflow from blower evaporator gets cold very fast and so does thermistor there. And then control module shuts compressor off


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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Sun Jun 07, 2020 7:27 am

sirrus wrote:
Sat Jun 06, 2020 10:23 pm
Shut off on its own after 30 seconds of working. Low pressure switch was still closed, so pressure should be ok. My theory is that without airflow from blower evaporator gets cold very fast and so does thermistor there. And then control module shuts compressor off


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Yes I agree with you, at my shop I have seen vehicles with otherwise properly working ac system cycling on/off because the cabin air filter is plugged (ie no air flow thru evaporator) new filter solves the problem,good job sounds like your getting the problems solved


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Tue Jun 16, 2020 7:49 pm

So I replaced blower and resistor today and AC is alive, blowing cold :) I noticed through the sight glass that flow of bubbles keep going after initial burst when compressor turns on - as I understand that means that it is a bit low on refrigerant.

So I'm thinking about topping it off with R12. Do I need a whole set of gauges (low and high side) for this or can I get away with just a can of R12 and charge hose for low side port? What would be better to determine if system is full - looking at low side pressure (as I understand that heavily depends on outside temperature and humidity) or filling until there are no more bubbles in sight glass? Or should I rent AC gauges, get R134-R12 adapters and fill it looking atr booth low and high side pressures?
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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Tue Jun 16, 2020 9:36 pm

Back in the day we used to just charge with R12 till the bubbles stopped,fast idle,hi blow, max cold, ambient temp at least 75 or higher, can’t do that with 134A much more sensitive to overcharging.


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Tue Jun 16, 2020 10:16 pm

Great info, thanks! Haven't thought about fast idle. I'll start looking for R12 cans and tap/hose on eBay then.

Another question - is it bad for AC to run it when it's undercharged like mine is? And R12 is not that sensitive to overcharging, right?
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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Wed Jun 17, 2020 5:32 am

In a perfect world one would want to recover the existing R12 recycle it, evacuate and charge with proper amount of refrigerant, making sure the system had the proper amount of mineral oil.
In the world of let's try this and see what happens,if the a/c is fairly cold then adding a little R12 till the bubbles are gone won't hurt,to tell if system is overcharged you need a set of guages, on a standard day should read around 30/150-250 more or less


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sat Jun 20, 2020 8:15 pm

Yeah, I'm definitely in a "let's try this and see what happens" realm :) Got a charge kit (tap, hose and a gauge) - so I'll be able to look at high side pressure during recharge, not just bubbles. Also found the table of pressure/temperature/humidity relation in TSM

Image

Next step is getting some R12 and charging. Probably a stupid question, but I'll ask anyway just to be sure - to operate service valves I need to take off those caps first or the caps themselves are connected to valve stem?

Image

As I understand the actual stem is under the cap, but once again, I just want to be sure before unscrewing anything :)
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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Sat Jun 20, 2020 8:57 pm

those are backseating valves with three positions, turned all the way counter clockwise the charge port is shut off,turn 1/2 way in (clockwise) opens port for charging,turned clockwise till stem seats shuts of hose.
The guage will work on either port (suction or discharge) but because you should only charge thru the low side(suction) you will have to use the red hose with the can tapper, so the guage will have to be on the high side(discharge) while charging, just be sure the high pressure doesn't get too high, max maybe 350lbs psi, lower is better maybe 150/200 lbs psi.
Last after charging put the guage on the low side to check pressure, 25/35 lbs psi desireable, make sure to turn the stems ccw and shut off the service port before disconnecting hoses.
BTW if you look at the compressor head there should be a S and D telling which service valve is suction/discharge.
Cheers


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Sun Jun 21, 2020 9:53 am

Thanks a lot, Ed! I think I have a pretty good understanding of what I’m about to do now I’ll post up the results when I’ll get to charging AC.


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1988 Grand Wagoneer - bone stock (AMC 360, TF727, NP229), slowly turning into reliable and nice daily driver

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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Wed Jul 22, 2020 1:00 pm

I've finally charged the AC :) Gauge I got has a fitting for low side port, didn't realize it until I had everything ready to go. So I was slowly charging and stopped right when bubbles disappeared from sight glass.

Checked low side pressure after - 30 psi, and ordered adapter for high side port to be able to check the that pressure later, just to be sure. AC is blowing ice cold now, I got 38 degrees at the vent with doors open and outside being 85-ish. Extremely happy with results

Thanks for the help!
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Re: 88 GW A/C revival and R134a retrofit

Post by sonoraed » Wed Jul 22, 2020 9:33 pm

Glad you got it going!


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Re: 88 GW A/C revival and R134a retrofit

Post by sirrus » Fri Oct 09, 2020 7:14 am

Who said anything about venting it to the atmosphere? I didn’t have to evacuate the system, so no problem here

BTW I knew that sounded familiar, you just copy/pasted from post on hagerty lol
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