The Air Conditioning thread...

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CathodeRayTube
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The Air Conditioning thread...

Post by CathodeRayTube »

about a year ago my AC compressor seemingly locked up whilst using the defroster last winter...smoke came out from under hood from the AC clutch (i think), took the belt off on the side of the road and haven't messed with it til now. Performed an autopsy of the compressor today and found several interesting things...the idler bearing was seized up and very stiff, but the compressor itself still turns freely...i dont remember seeing the clutch actually slipping last winter when i peeked at it on the side of the road, but everything definitely got very hot. This leads me to believe that the idler bearing is what created the heat and was smoking and not necessarily the compressor locking up itself...the clutch does appear to have been slipping...but after taking the compressor completely apart and seeing that its basically fine, im confused as to what actually happened...either the idler seized up and caused the smoke etc...or it was just on its way out anyway and the compressor actually did lock up and smoke the clutch...and because theres no damage inside the compressor, i can only think that perhaps i way over charged the system and it hydrolocked itself with liquid refrigerant...

would liquid refrigerant cause it to totally lock up like this? the way the compressor is built i would think it should handle liquid refrig. OK...i would think overcharging would cause other problems first also...like it not cooling...it worked up until the smoke.

No serious damage in the compressor, however there was a small internal thrust bearing that was shot and scraping, accounting for the scraping noise compared to the other good spare i have...but this hadnt yet caused any sort of catastrophic failure yet.

Im planning to keep the dissected compressor around for further investigation or a rebuild later... and im planning to do a preemptive rebuild/reseal on the spare one before i put it in the car. Im having trouble locating a complete seal kit for it...

Also, im interested to hear others thoughts on two controversial things...the use of R290 (Propane) in place of R12... which has worked well for me in other vehicles and has pros that outweigh negligible cons. And then something else really far out there that i just thought of today after dissecting the compressor...Using Gear oil in the A/C system in place of refrigerant oil...after seeing the inner workings of the compressor and all the sliding-action, it made me think of gear oil..which is meant for hypoid gears that also do alot of sliding...actual R12 refrigerant oil is just mineral oil, is pretty thick, and is also pretty expensive... Propane is known to mix with real refrigerant oil very well which is partly why its well suited as an R12 replacement...but would it mix well with gear oil? and what other adverse affects may happen if its in an A/C system that anybody can think of..? Just some thinking outside the box here...il probably try it anyway to see what happens for the sake of experimentation, unless i figure out or hear a good reason not to. Im basically dealing with old junk anyway so if i fry a compressor it doesn't really matter..

Il post pictures of the dissected compressor internals later if anybody is interested.
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Mark
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Re: The Air Conditioning thread...

Post by Mark »

Every refrigerant oil I've worked with (not in cars admittedly) has special wax-free properties. Some of the oil is carried along with the refrigerant and when it is exposed to low temps after the thermal expansion valve, wax crystals could form in regular oil, clogging small passages (TXV). The cloud point is the temperature at which these crystals form. I'd check the MSDS sheet for the cloud point for any oil you want to use. Then there's also the viscosity, etc. I'd stick to the proper refrigeration oil.
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Re: The Air Conditioning thread...

Post by CathodeRayTube »

That probably is the best plan. It is pricy but looking on Ebay, R12 mineral oil isnt that much more expensive than synthetic gear oil...and id use so little of it in these projects that its probably worth just using the proper stuff...that and the R290 is already a wildcard to deal with. Still cant help but think tho that gear oil might actually be a benefit in the compressor if not for the wax issue, and if it would mix with the refrigerant and not attack copper/brass parts in the system (dont think there are any?) etc..
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Re: The Air Conditioning thread...

Post by splatterdog »

For best results, use the proper materials. Once you contaminate it you either need real expensive flushing equipment with super expensive solvent or replace EVERYTHING. As demand dwindles so does the price of R12. Gear oil is a real bad idea, it won't be carried by the refrigerant.

I would go with this before trying to re engineer a system that worked good enough for the car manufacturer.https://images.search.yahoo.com/images/ ... r2=piv-web
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Re: The Air Conditioning thread...

Post by irowiki »

I thought R12 was practically unobtainable?
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Re: The Air Conditioning thread...

Post by splatterdog »

Can't be manufactured or imported. Lots still around though. Between c-list and garage sales I've acquired a nearly new ac machine and 90lbs of r12 for under $500.
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Re: The Air Conditioning thread...

Post by CathodeRayTube »

I have a few cans of the real stuff stashed as well that i managed to score for free...but im saving that for if i find a fridge or a window A/C that i want to keep going...otherwise im sold on propane...legal & flammability issues aside, its a great functional replacement, mixes with existing R12 & mineral oil in a system, is more efficient and actually colder than R12, the compressor doesnt work as hard which saves gas, is totally safe for the environment, is cheap (coleman bottles)...and is widely used in Europe for the same purpose. Iv had 4 other vehicles that it works wonderfully in...and on my recent drive across the country in the 86 Mercury, it was almost too cold even in the Nevada desert...they also sell it as actual refrigerant anyway as R12a or HC12a...but for a higher price and with more red tape.

The gear oil idea...maybe isnt the best idea...however looking on Mobil 1s website they state that there product is made from a wax-free synthetic base...might call for an experiment...spray some liquid propane into a heavy jar with a lid and some gear oil and close it up before it boils off and see if the two liquids mix...

There is also a black market for real R12 as well..i believe its still being smuggled in from Mexico in small quantities.
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Re: The Air Conditioning thread...

Post by Mark »

Do you use R134a in the US? I'm pretty sure that's the replacement for R12 up here. In a big industrial-style system I work with, that's what it was switched to years ago. I think most cars up here use it now too. It's non-ozone depleting and you can buy it off the shelf in the automotive section of many stores (Canadian Tire for example).
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Re: The Air Conditioning thread...

Post by CathodeRayTube »

Yes, R134a is the standard here in the US now. However it is not totally ozone depleting...it still does just less than R12 did. I hear talks about the industry moving to carbon dioxide as a refrigerant...however that works at extremely high pressures and is less mechanically efficient than 134a...which is already poor compared to 12.
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Re: The Air Conditioning thread...

Post by Mad_Marx »

So, I converted Terc II to 134A with the $40.00 kit from NAPA, this involved replacing all the O-rings in the system with 134A safe O-rings. I did this while doing the heater core, talk about a fun job... :/ I had to buy a new set of manifold gauges for charging the system as my old Snap-On R12 gauges did not fit the newer fittings and apparently no adapters are available. I was able to apply vacuum to the empty system for almost an hour and it held vacuum. I was able to charge the system, and the Air blows cold, but takes longer to get cold, and does not blow as cold as it did with the old R-12 refrigerant. So here's my question (sorry for the long way around). Does anyone know what manifold gauge readings should be as compared with the FSM? The new AC gauges have a scale that is specific to 134A. The FSM says the high pressure side should be 14.0-15.5 kg/cm2 (199-220 psi, 1,337-1520 kPa). I suspect the two different refrigerants have different viscosities and do not respond the same under various atmospheric pressures. Anyone else have a 134A converted system? What should I be looking for?

Thanks in advance

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Re: The Air Conditioning thread...

Post by Mark »

I think the temperature at which the refrigerant will condense at around 200 psi is pretty close for both refrigerants (55 vs 58 degrees Celsius). I'm not familiar with automotive AC systems since I live on the West Coast of Canada and I've never had a car with AC so I don't know how automotive systems control the condensing of refrigerant in the condenser. On systems I'm familiar with, if the refrigerant is not condensing due to not enough cooling air/water through the condenser, there is a high pressure switch that will shut the system down. I don't know if cars have this. If it doesn't have this switch and the refrigerant isn't condensing fully, there will not be much cooling effect in the car. Does the condenser have a cooling fan and is it working? Is the condenser covered with dirt or dust that would restrict airflow?
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Re: The Air Conditioning thread...

Post by irowiki »

Converted Party (87 Tercel) to R134 from R12, system didn't really work before (must have been low). Doesn't seem to get THAT cold...but the car is dark brown and is a total oven in the hot sun.

With a turkey thermometer in the center vent it gets about 60-70F on ECON and 50-60F on AC. Seems like it should be colder? Was thinking of turning the amplifier just a little colder.

The 92 Camry was also converted to R134 and it gets down to 40F with the AC on, averaging about 45F.

After running the Camry on high and driving from work when it is in the 80's (starting with a roasty car), after 5 minutes it is too cold and I have to turn the fan down.

On the Tercel on the other hand, I can run it on high the entire 15 minute trip home and it never gets too cold, it is "just enough" or "barely enough".

So maybe we can brainstorm together!

I need to double check that the condenser is clean. The fan does operate.
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Re: The Air Conditioning thread...

Post by Mad_Marx »

Thanks again for quick feedback I won't have time to experiment with mine until this weekend, but my experience has been close to irowiki's. I checked the relay and switch as per FSM. Haven't touched the amplifier yet. It was 98 here yesterday, I hope to have it tip top before we get our typical 3 to 5 weeks of triple digits.

I'll keep you posted
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Re: The Air Conditioning thread...

Post by Petros »

I converted a Tercel to use the new refrigerant, it seemed to work okay but I never had a working Tercel to compare it to. We dont really need a/c here, that car I installed the whole system in and had it coveted and charged because it was going to Texas. Unfortunately on the drive there the A/c stopped working, I learned refrigerant leaked out after leaving for Tx. I spent some time diagnosing it, and yes, it has a pressure switch that shuts the system off if it has no refrigerant. That what how I knew the refrigerant leaked out, I disconnected the switch (it is right behind the glove box), and the clutch engaged and the compressor was turning, but no cold air and no refrigerant could be seen circulating past the little window. So I shut it off real quick. And realized all of that new refrigerant had leaked out.

I was over 1000 miles away from the shop that tested it and installed the new seals and the refrigerant, so I did not bother to take it back. Figured if my daughter wanted the a/c so bad she could have the leak fixed and the system recharged, it was working so all it needs is to keep refrigerant in it.
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Re: The Air Conditioning thread...

Post by CathodeRayTube »

You basically have to totally flush and clean the entire system out and replace the oil for it to work properly converting from 12 to 134a...the 2 refrigerants themselves do not mix together, and they both use different oils. but propane does mix with r12 and r12 mineral oil. 134a is also less efficient than 12, so it needs a larger heat exchangers (evap & condenser) to have the same cooling affect...just adding 134a to an existing 12 system will only work so well or may damage the compressor...

I ended up rebuilding my compressor that i was talking about in this thread originally...only thing wrong with it was the one bearing was just beginning to fail but probably would have gone for a long time yet...no idea why it originally locked up...perhaps the clutch was at the end of its life and started slipping badly... I used genreric Chinese rubber O rings from Ebay to rebuild the compressor, barring the availability of an actual rebuild kit...they promptly blew out allowing all the refrigerant to escape again and i havent bothered with it again this year yet...il probably get a new compressor next attempt and keep using propane. I did try putting the gear oil in it, but it wasnt in long enough to find anything out...i dont think the seals blowing again had anything to do with it tho.
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