1990 A/C Question - stick with R12 or change to R-134

[OP240sx]

My A/C is blowing warm air, Friday was working great and Saturday is was not. I know the compressor still works as it cycles on and off just like normal, just no cold air comes out the vents. It is the R12 system, and I currently have 12 cans of R12 freon. I tried charging the system last night using about 1/2 of a can and nothing changed, still warm air. I stopped because I did not want to waste any not knowing if I was doing any good. I was at least hoping to feel the air temperature change to know that it is working correctly and just low on freon. Should I go ahead and try more?

I was planning to take it to the dealer to have them check it out, but they want to convert it to R-134A using their $40 kit.

What the likelihood, that it will only need that kit and not a bunch of other parts?

I just don't know what to do. Should I go ahead and convert it if some of the parts are bad, they will have it apart anyway, or should I stay with R12 since I have the freon?

Sorry for the long question.Thanks.

[navysnail]

i would stick with r-12, i hope that you know that r-12 is illegal to manufacture or vent into the atmosphere, so: have a profesional evacuate the system and find out if there is a leak, and have him use your r-12 to refill it (r-12 is currently about $50 to $60 a pound, so you could sell one or 2 cans and convert the system if you wanted) .the thing is, that r-134a will not blow as cold

before charging, use a pressure gauge too

[DAEDALUS]

If the compressor is cycling on and off then the system has adequate pressure in it. The compressor might be bad, all you're hearing is the clutch. Feel the temps of the metal lines going to and from the AC.

[OP240sx]

i would stick with r-12, i hope that you know that r-12 is illegal to manufacture or vent into the atmosphere, so: have a profesional evacuate the system and find out if there is a leak, and have him use your r-12 to refill it (r-12 is currently about $50 to $60 a pound, so you could sell one or 2 cans and convert the system if you wanted) .the thing is, that r-134a will not blow as cold

before charging, use a pressure gauge too

Yep, I am aware of the R12 laws. Currently I plan to get it evacuated, checked for leaks, repaired if necessary, and refilled with my freon. If I didn't have the 11 1/2 cans of R12 I would probably get it retrofitted because of the cost of R12. I haven't put any in the car for about 4 years, that is before this happened. I read that if you can stay with R12 it is better because as you said, the r-134a will not perform as well.

[OP240sx]

If the compressor is cycling on and off then the system has adequate pressure in it. The compressor might be bad, all you're hearing is the clutch. Feel the temps of the metal lines going to and from the AC.

Don't say that!!

If the compressor was bad, wouldn't it seize up?

What if the dual pressure switch was bad, that would affect the system even if it had enough pressure, right?

Damn A/C, love it when it works, hate it when it doesn't.

[navysnail]

compressor can also go bad and not engage at all, but feel the lines like daedalus said, thats the best way

if you ever decide to get rid of a can or two, i could always have some spares on hand incase my system decided to vent

[s13sr20chris]

yeah, feel the lines. that tells you all about the refrigeration sys performance. if thats good, check the air mix door operation. to diag a low condition you really need pressure guages.

[PoorManQ45]

What has to be done to convert a R-12 system to R-134?

Does any of the hardware need to be changed? Or does the R-12 just need to be thoroughly flushed out and refilled with R-134?

Will the compressor work with R-134? I have heard that R-134 systems operate at a higher pressure. Is this true? If so, will an R-12 compressor be able to operate reliably at the higher pressures?

[OP240sx]

What has to be done to convert a R-12 system to R-134?

Does any of the hardware need to be changed? Or does the R-12 just need to be thoroughly flushed out and refilled with R-134?

Will the compressor work with R-134? I have heard that R-134 systems operate at a higher pressure. Is this true? If so, will an R-12 compressor be able to operate reliably at the higher pressures?

I found this when googling the subject.. http://www.delanet.com/~pparish/nis-rp.htm

It says the compressor can work with R-134a, but you do need to get all the R12 and oil out before you can complete the retrofit. It does run at a higher pressure, uses different oil, and is not quite as good at cooling as R12. That's what I read anyway.

Taking mine in Friday to get the diagnosis. Preparing myself for what might be an expensive repair. If the compressor is bad, I will just have to decide on whether to retrofit or not. I would really like to stay with R12 because the A/C works fantastic, even here in hot, sunny Florida.

Question, how many 12 oz cans of R12 would it take to fill the system?

[DAEDALUS]

Just a guess, probably 3-4. R-12 rubber hoses don't work well and need to be replaced with barrier hoses. R-134a molecule is smaller than R-12 and will seep through.

[s13sr20chris]

3 ways to retrofitstraight up evac and recharge(works ok)evac, flush, recharge(best option)evac, replace components, recharge(works better but expensive)you get what you pay for. i have tried all three and i prefer no. two.

[OP240sx]

If the compressor is cycling on and off then the system has adequate pressure in it. The compressor might be bad, all you're hearing is the clutch.

You called it. The compressor all chewed up inside..?? Nissan quoted me $1000 parts/labor.

Anyway, going to the internet to buy a reman comp, new dryer, and they said I might need an expansion valve. They are going to install it for $240.

Now for the $64 question, what should I do now that I have to replace the compressor, should I stick with R12 (I have lots of freon) or go to the R-134a system? We plan on keeping this car forever.

If I did convert, other than the conversion kit and the parts listed above, anything else I should buy?

Thanks for all the expert knowledge.
Modified by OP240sx at 4:31 PM 9/17/2004

[DAEDALUS]

I'd say stick with the R-12. Less chance of compatibility issues in case you don't get all the old oil out, plus R-12 cools better.Conversion requires you replace all seals, plus the flexible hoses in addition to the compressor and drier (will the compressor work with R-134a?). Assuming you fix any leaks the system should last as long as the reman compressor. The cost of the R-12 isn't much compared to everything else, especially when you've already paid for it.See if they'll refill the system without charging you for the R-12. Heck, they're taking the R-12 out of there, right? It's yours, and it will get recycled. That's my logic. Didn't fly with the shops I called, though, so I said F-U and bought my own damn AC machine.

[OP240sx]

I'd say stick with the R-12. Less chance of compatibility issues in case you don't get all the old oil out, plus R-12 cools better.Conversion requires you replace all seals, plus the flexible hoses in addition to the compressor and drier (will the compressor work with R-134a?). Assuming you fix any leaks the system should last as long as the reman compressor. The cost of the R-12 isn't much compared to everything else, especially when you've already paid for it.See if they'll refill the system without charging you for the R-12. Heck, they're taking the R-12 out of there, right? It's yours, and it will get recycled. That's my logic. Didn't fly with the shops I called, though, so I said F-U and bought my own damn AC machine.

The compressor will work with R-134a. I think I am going to stick with the R12.

I don't claim to be any sort of mechanic, so how hard would it be to change out the compressor and dryer, after the system is vacuumed out? It doesn't look too hard, just unbolt the a/c lines and replace the parts.

They also said the my expansion valve MIGHT be bad as well, but they won't know until they replace the broken parts and recharge. My problem is that they want about $320 labor just to replace that part. I know it's under the passenger dash, but I really can't tell how hard it would be to get to the part. After looking at the FSM, it looks like it just bolts on as well, just getting to it would be the hard part. Seeing as how I was going to try to replace the other parts, if it's not too difficult, I thought I would try this as well while the system has no freon/oil in it. Is it really hard to reach that part?

Thanks.

[s13sr20chris]

wether or not to do xvalve is just a cost/benefit analysis. can you get one for cheap? its easy to replace. once the sys is evacuated you just:1)remove glovebox2)disconnect a/c lines3)remove evap case4)disassemble and reassemble with new xvalve5)put all that stuff back in

wish i still had mine i would give it to you.

[OP240sx]

1)remove glovebox2)disconnect a/c lines3)remove evap case4)disassemble and reassemble with new xvalve5)put all that stuff back in

wish i still had mine i would give it to you.

Well, assuming I can get an expansion valve for a decent price, how hard is it to get the evaporator case out? The glovebox and A/C lines look to be no problem.

One more thing, Nissan charged me $65 for a diagnosis in which they evacuate, check for leaks, and recharge. They claimed they injected dye into the system to check for leaks, but they never mentioned any, only a bad compressor. I was under the impression that to check the entire system for leaks, the compressor would have to function to pump the dye through the lines. Am I correct?

I know they didn't evacuate the system because I am pretty sure they don't have an R12 machine...??? As far as evacuating the system, they were going to discharge the R12 to the atmosphere, of course those weren't the words they used.

[s13sr20chris]

whoa, thats throwing up my "bad shop" flag. a dealer is going to do that? the dye wont do much if the comp does not work. they are just putting you in a standard service that does not apply to your situation. i guarantee they just want to take your money and you go away.

[OP240sx]

whoa, thats throwing up my "bad shop" flag. a dealer is going to do that? the dye wont do much if the comp does not work. they are just putting you in a standard service that does not apply to your situation. i guarantee they just want to take your money and you go away.

I was afraid of that. It's strange because that's the place we have always taken it to get maintenance. I am going to call the service writer and see what he has to say for himself.

I've decided that I am going to replace the compressor and dryer myself after I get the system discharged. I ordered the parts/O-rings off the net. Then I will take it back have them check it for leaks, evac & recharge with my freon. I am hoping that the expansion valve is still working okay because I would rather not tear apart the dash for no reason.

If the freon is discharged using an R12 machine, can it be put back in after the fixes are done?

Thanks

[DAEDALUS]

Yes, but if the shop isn't a good one to start off with then be very wary. A good shop will test every single system for purity before recovering the fluid. There are a lot of hacks out there who will do anything to get their AC working, and this includes pumping one of many commerically available refreigerants/substitutes into the system. If your shop recovers refrigerant from any of these cars, the entire batch is contaminated and you don't want them pumping any of that stuff back into your car. Otherwise, yes, they recycle it and they should reuse it. Notice I said "should" since, as I mentioned earlier, I found it's not so easy.

[OP240sx]

Yes, but if the shop isn't a good one to start off with then be very wary.

This is a Nissan dealer I am speaking of, not Bob's Auto Repair. He actually owns two, a Ford and Chysler/Jeep dealerships too. It doesn't seem like it should be this way.

[OP240sx]

So here's my latest update. The local Nissan dealer only has a manual pump to discharge the system, and he told me that it WOULD NOT put the freon back in. So any freon they take out, I lose.

I am trying to decide what to do on that expansion valve. I can either replace it along with the compressor, dryer, and DP switch and be in good shape, but the part MIGHT NOT be bad. On top of that, the job looks to be a PITA, remember Nissan wants $320 labor to replace the $50 part. If don't replace it along with the other parts and it is bad, I lose whatever freon is in the system because their junk machine won't discharge and then recharge.

The A/C section of the FSM didn't really show too well how to get at the expansion valve. What would you do?

Also, if the system is fixed and has been evacuated, can they add 1/2 a can of freon to see if all the components are working properly, especially the exp. valve if I decide not to replace it, or would the system have to have a full charge to do a proper diagnosis?

thanks.

[Touchdown038]

I just got done restoring my A/C this summer, and I can tell you from experience that the expansion valve is not too hard to get to. Honestly, getting the glove box out was about the toughest part. Then just unbolt the lines from the engine side of the firewall, unbolt the box, pull the box and change the valve.

As far as the shop not refilling your Freon after evacuating goes, you could probably find a good shop that will do it for you, maybe for a price. I'm not sure where you're located but there's about three different A/C specialized shops in my area, a town of 25,000.

[OP240sx]

I just got done restoring my A/C this summer, and I can tell you from experience that the expansion valve is not too hard to get to. Honestly, getting the glove box out was about the toughest part. Then just unbolt the lines from the engine side of the firewall, unbolt the box, pull the box and change the valve.

Well, I think I just might try to change it out myself. If for some reason I mess it up, I'll just have them fix it.

Since you just recently worked on yours. Can you give me any tips/things to look out for? I was reading that I should change the dryer last to keep the moisture out of it. I did order the dryer for the R12 system since it has the different desicant (sp?) inside vs R-134a. I ordered new O-rings for that and the compressor.

Sure will be glad to get it working again, even though it's sort of starting to cool down here in Florida - 80's today.

[s13sr20chris]

heres a tip. if you put the xvalve in yourself use plenty of penetrating oil on the evaportator lines(coming through the firewall). also use a backup wrench if possible. they rarely freeze up but when they do it sucks. i usually reccomend nissan dealerships for work but if they are not going to put your r12 back in then the heck with them. you can get it done somewhere else.

[OP240sx]

heres a tip. if you put the xvalve in yourself use plenty of penetrating oil on the evaportator lines(coming through the firewall). also use a backup wrench if possible. they rarely freeze up but when they do it sucks.

Thanks for the tip. I will definitely get some of the penetrating oil.

i usually reccomend nissan dealerships for work but if they are not going to put your r12 back in then the heck with them. you can get it done somewhere else.

Yeah, as far as handling the freon, they don't offer much. They will put my R12 in if I ask them to, it's just that whatever they take out, can't be recharged back into the system. I have 11 1/2 cans, but I still don't want to waste any.

[DAEDALUS]

Yeah I don't accept that answer either (obviously).

The back-up wrench is at least as important. You're putting a lot of torque on the fitting and you don't want the thin-walled lines taking the stresses. They often break like that.

Between the dye and sniffers IMO sniffers are much easier and faster to use to find leaks.

[s13sr20chris]

sniffers are nice. i wish i could get my hands on one. tool bill so high already. good thing nissan a/c dont leak as much as the caddys.

[DAEDALUS]

It's an expensive tool for an individual who isn't a full-time AC person, but I don't see any reason why a shop wouldn't have at least one. Compared to the cost of the AC machines and purity testers, it's not too bad. You have to wonder if the shop even has a purity tester if they don't have a sniffer. 5:1 cost ratio roughly.

[s13sr20chris]

my dealership has neither. if we did, surely a $7/hr luber boy would break it.

[OP240sx]

Well, I should receive the rest of the parts today, expansion valve and more O-rings. I already have my reman. compressor ($165 off ebay vs about $600 from Nissan), dryer (complete with new dual pressure switch), and more o-rings. I was not aware that a new DP switch came on the dryer so I am having to send the extra one I ordered back.

Anyway, does the R12 freon in the cans already have the oil for the system, or is this something that I would buy separately and add to the compressor prior to installation? I think I am going to have Nissan charge the system, since I don't have any gauges, but I don't want to assume that they know what they are doing with this "old" system.

I am going to change the belts while I'm at it.