LJ78 Air Conditioning Repair?

[GTSSportCoupe]

I did some searching but did not find much (maybe I didn't use the right key words, don't know).

My LJ78's A/C has never worked. I've been doing some long trips with my family, and it would be nice to get it working again. Especially for the kids.

Has anyone repaired their A/C system themselves? What is involved? I know very little about A/C, but am willing to learn. Or would I be better off just paying someone to repair it? I'm not loaded $$, so prefer to do it myself if possible.

Thanks for any ideas or a point to a thread on the subject.

 

[Gun Runner 5]

I did some searching but did not find much (maybe I didn't use the right key words, don't know).

My LJ78's A/C has never worked. I've been doing some long trips with my family, and it would be nice to get it working again. Especially for the kids.

Has anyone repaired their A/C system themselves? What is involved? I know very little about A/C, but am willing to learn. Or would I be better off just paying someone to repair it? I'm not loaded $$, so prefer to do it myself if possible.

Thanks for any ideas or a point to a thread on the subject.

When I first bought my LJ78 the A/C did not work either. The problem was the rheostat style "on-off" switch which I simply replaced with a toggle switch. After that it was good to go.

 

[GTSSportCoupe]

When I first bought my LJ78 the A/C did not work either. The problem was the rheostat style "on-off" switch which I simply replaced with a toggle switch. After that it was good to go.

Wow! That must have been nice! I'll have to test mine. That would be great if that is all it is. The on/off dial switch doesn't feel like it is actually doing anything...no 'click' or anything.

Although having not run for years now it could be the seals dried out in the mean time... I'll be looking at this tonight and will report back.

 

[Gun Runner 5]

My rotary switch did not click either ( first clue ) but when the compressor was "direct wired" it came on. ( second clue ). If I remember correctly we also converted the system to the modern freon. It was working fine when I sold the Cruiser.

 

[roscoFJ73]

Wow! That must have been nice! I'll have to test mine. That would be great if that is all it is. The on/off dial switch doesn't feel like it is actually doing anything...no 'click' or anything.

Although having not run for years now it could be the seals dried out in the mean time... I'll be looking at this tonight and will report back.

The rheostat switch does not make a click but you can hear/feel the compressor cut in as the magnetic clutch is activated.
The magnetic clutches fail sometimes.They are about $250-$300 new in oz
I think the best way is to get the compressor working and then have it pressure tested. I think they pump them full of nitrogen to see if its leaking.

 

[Gun Runner 5]

The rheostat switch does not make a click but you can hear/feel the compressor cut in as the magnetic clutch is activated.
The magnetic clutches fail sometimes.They are about $250-$300 new in oz
I think the best way is to get the compressor working and then have it pressure tested. I think they pump them full of nitrogen to see if its leaking.

Maybe there was a cricket in my floorboard but I was fairly certain there was an audible "click". Perhaps it's time for a hearing check.

 

[Rummat81]

1. make sure that the AC belt is no loose and properly tight.
2. Engine running, give 12V supply to the compressor for a few seconds if it engages one and off repeated then your clutch is fine.
3. the system is probably low on Gas.
4. either consult a car AC guy for testing the system for leaks/fill or if you want to go cheap, get a DIY kit from Princess auto/CDN tire and see if the system holds charge for any reasonable amount of time.
Hope that helps.

 

[GTSSportCoupe]

1. make sure that the AC belt is no loose and properly tight.
2. Engine running, give 12V supply to the compressor for a few seconds if it engages one and off repeated then your clutch is fine.
3. the system is probably low on Gas.
4. either consult a car AC guy for testing the system for leaks/fill or if you want to go cheap, get a DIY kit from Princess auto/CDN tire and see if the system holds charge for any reasonable amount of time.
Hope that helps.

Thanks a lot!! Glad to see you on the forums again! How's your rebuilt 2lte running?

Turns out my rheostat style switch appears to be fine and there is a relay click under the dash when I turn the switch.

I'll hot wire the compressor clutch as you suggested and make sure it's ok.

I've wondered about those princess auto/ can tire kits. Might give one a try for the heck of it and see if I can save a few dollars.

Thanks again!
Nick

 

[GTSSportCoupe]

So I hot wired the compressor electromagnetic clutch to 12V, and sure enough it works fine. I ran it for a bit to see if the A/C would actually work, but it didn't seem to cool the air in the truck at all.

I also removed the caps from the service valves, and pushed on the valve a bit to see if there was any pressure in the system. Definitely got a little 'pshttt'. I didn't let much gas out, but I'm glad the system still has some pressure in it. Gives me hope that there are not any really bad leaks.

I'm going to read the manual (RM183E) A/C and electrical sections and run through the proper troubleshooting etc. to make sure I"m on the right track.

Will post back when I figure it out.

 

[Coolstream]

I'm certain that somewhere in the system is a low pressure switch that will cut power to the compressor if the system is low on refrigerant. If it's not cooling well when you hot wired the compressor, there's a high likelihood that the system is low. Is it an R12 system? If so, look for the sight-glass, often on top of the drier, and look for bubbles in the window when you have the system running with the compressor hot wired. Bubbles mean it's low. This is not really an accurate check if you have R134a.

 

[GTSSportCoupe]

I'm certain that somewhere in the system is a low pressure switch that will cut power to the compressor if the system is low on refrigerant. If it's not cooling well when you hot wired the compressor, there's a high likelihood that the system is low. Is it an R12 system? If so, look for the sight-glass, often on top of the drier, and look for bubbles in the window when you have the system running with the compressor hot wired. Bubbles mean it's low. This is not really an accurate check if you have R134a.

Thanks for the tips! I think your are right about the low pressure switch. I believe it is a R12 system (1990 JDM truck). I did look in the Receiver sight-glass, and saw just a little bit of clear fluid blowing on the glass surface and that is it. So I'm guessing that means I'm very low on refrigerant.

 

[BCR4619]

Hey GTS been following your threads and builds, good stuff!

I know a guy over here on the mainland had got some R12 shipped up from the US to the boarder and recharged his system and he says it works like a charm. If I were you I would get it evacuated and change all the o-rings/dryer and add oil to the system once you figure out what you wanna run.

I have been looking into this too as my R12 is kinda low but it blows cold with the recirculating mode selected so I am not in dire need of it yet.

 

[GTSSportCoupe]

Hey GTS been following your threads and builds, good stuff!

Hey, thanks a lot man. One doesn't get compliments like that every day.

I know a guy over here on the mainland had got some R12 shipped up from the US to the boarder and recharged his system and he says it works like a charm. If I were you I would get it evacuated and change all the o-rings/dryer and add oil to the system once you figure out what you wanna run.

I have been looking into this too as my R12 is kinda low but it blows cold with the recirculating mode selected so I am not in dire need of it yet.

Thanks for the advise. I'm so tempted to cut corners on this job for some reason, but instead I should take my time and do the job right (as you suggest). I think I remember reading a thread that had something to do with what you mention. Is that in the 80 series forum? I'll do a search...

 

[BCR4619]

Search HDJ81 r12 something, his name is Spurcap I believe.

 

[Gun Runner 5]

If you can find R12 at all, it is VERY expensive, at least here in the U.S. Hopefully that is not the case in Canada.
I just had my BJ74 converted to the new freon ( approximately $100.00 USD ) which is readily available.

 

[GTSSportCoupe]

Found some advice on another forum (http://forums.tdiclub.com/showthread.php?t=145180) with regard to the red-tek style R12A kits. As with all things on the web, this is just one person's experience and opinion. I put in bold points what I found of particular interest. Read the thread for more info. The guy's handle whom I quoted is "rotary kid". Seems to be a refrigeration specialist.

"
Hydrocarbon refrigerants are the most efficient refrigerants that exists using much less energy to produce their cooling effect .

The Red Tek products are hydrocarbon mix refrigerants that have been widely used throughout the world for over 10 years for a chlorofluorocarbon replacement in industrial and auto applications .

I've been using it as it was intended to be a "Drop In" replacement for chlorofluorocarbon R12 , R22 , & R509 . No seal or oil replacement required . In Canada no valve replacement , but in the US the connection valves must be retrofit to the R134a connectors . R12a is also a "Drop In" for R134a .

As with all hydrocarbon refrigerants much lower head pressures are required . Lower head pressures equal less system wear and longer system life .

And yes it is true that these refrigerants do operate better without a vacuum being applied before the fill . A vacuum should still be used to verify that there are no leaks but must be released before refilling the system .

Moisture can cause the system to work very poorly when using R12 & R134a but it can be helpful in small amounts while using hydrocarbon refrigerants .

Hydrocarbon refrigerants require less volume to work as compared to what they are replacing . If using this stuff pay attention to the conversion rates as overfilling will cause a less efficient system .

6 ozs of R12a , Equivalents to ;

= 16 ozs R134a

= 18 ozs R12

8 ozs of R22a , Equivalents to ;

= 20 ozs R22

Red Tek also sell a wide range of products that work with their refrigerants .

"ProSeal" is for sealing cracks in evaporating coils , condenser coils , & cracks in hard rubber hoses . Yes it does work I've used the stuff to repair systems with leaking hoses and cracked coils .

"ProLeakStop" is a ac seal treatment that swells seals , repairs leaky seals , & conditions O-rings . I've seen this stuff repair compressor seals that were leaking before it was applied .

"Universal Oil Charge" can be used to add oil to a system that has lost some the oil after a system leak down .

There are other things they sell but these are things that I have tried .

A farm supply dealer is the best place to look for the stuff as it is widely used to replace R12 in tractors & freezers .

Unless the cars system has been open to the air for a while no dryer receiver replacement required .

Unless you have blown a hose and lost all of your freon at once then no replacement of oil is required .

Vacuuming the system down is only needed if you think there is a leak .
"

 

[Coolstream]

Since hydrocarbon refrigerants (propane or butane) were never designed to be used in automotive A/C systems, here are a couple things to consider. They will certainly work in an A/C system, although I have doubts that it will work better than R12. One thing they fail to mention is that 19 states in the US have prohibited the use of hydrocarbon refrigerants in mobile A/C systems...another thing to consider, many A/C hoses use Chloroprene as their inner layer, propane will attack and swell the hose. I'm sure they will tell you that the risk of fire is minimal, but last time I tried, my propane torch seemed to ignite just fine. One last thing, check any compressor manufacturer about what warranty they will offer if you use a hydrocarbon refrigerant.

Propane compatibility

Hose materials and construction

 

[GTSSportCoupe]

Thanks for the heads up coolstream! I appreciate your experience and knowledge.

After lots of reading online (and the FSM), I decided to risk the Red-Tek 12a kit. Because my system still had some pressure and had not been opened up, I knew there was a good chance my dryer/receiver was still in ok shape, and the system was clean and still had oil. Of the people that have actually used the Red-Tek style kits, most only had good things to say and there were few bad experiences. Most did not evacuate their system before adding the Red-Tek refrigerant, and had not issues even so.

So I bought the kit at Canadian Tire http://www.canadiantire.ca/AST/browse/4/Auto/AirConditioning/AirConditioningRefrigerant/PRD~0146129P/RED+TEK+A%2BC+Refrigerant+Recharge+Kit.jsp?locale=en. The kit had all the bits I needed. No special extra parts required. Cost me $55 before tax. (Kit is cheaper at some other retailers...)

I carefully followed the instructions and tips I'd read on the net. My system ended up using the full two cans to achieve 35psi at idle on the low pressure side with the compressor running. As soon as I got pressure in the system, the low pressure switch worked again, and allowed power to turn on the compressor. I began getting cold air after the first can, and even colder air after the second!

So, all said and done it seems to run great and blows nice cold air. I'll be using a little oil tester from the kit to make sure I've got enough oil in the system. If I don't have enough oil I'll buy some of the red-tek oil and add it.

I'll keep this thread up dated with how things go and whether any issues arise.

Thanks for the help everyone.

 

[GTSSportCoupe]

Went for a 1 hour drive yesterday on the highway. A/C worked EXCELLENT. More capacity than I needed. I still can't believe how easy it was to recharge myself.

Last night I used the oil tester that came with my kit. The tester indicated the oil in my system is clean and there is lots of it! This is the factory oil still; I did not have to add any.

So now I'll just have to see how the Red-Tek stuff works for the long term. Will post here if I have any issues with it.

 

[VI Cruzer]

Thanks for the post Nick, I had been wondering how hard it would be to recharge it meself. I have to get mine re-charged every second season.