Mudweiserjeep
NAXJA Forum User
- Location
- tipp city, ohio
sounds good....thanks Shorty
-
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Air Conditioning Trouble Shooting
- Thread starter splitz
- Start date
Rick Anderson
NAXJA Forum User
- Location
- Lusby, MD
I can't argue with playing it safe, and pulling a full vacuum before servicing an AC system.
BUT, in most cases, even if the AC system leaks down enough the compressor won't even engage, there will still be enough residual pressure in the system to create an overpressure and prevent anything from leaking in. You have to use a little common sense here, obviously if had a line break, had a fast and large leak develop or opened a line completely, air and moisture has leaked into the system. As well, if your system has been totally depleted for years, the natural cycle of air pressure with weather may have got to the point where one day the ambient air pressure exceeded what was left in the system and forced some air and moisture into the system.
But, in most cases, where the system is leaking very slowly and your AC was getting weaker slowly over time and now is at the point where the compressor is cycling excessively or won't engage at all, when it was engaging (cycling) a few weeks before, its very likely there is still enough pressure left in the system to keep any air or moisture from leaking in.
Again, your taking a risk, and you really should never service an AC system yourself unless you have the proper set of gauges (hi and low) and know what they mean.
What it comes down to, with AC if you value the system and don't know what your doing, just take it to a pro to be serviced or repaired, your far more likely to destroy the system and cost yourself far more to repair it doing a ham-fisted diy servicing.
If you don't really value the AC and are NOT willing to pay the money for the Pro, take your chances and do it yourself, not knowing what your doing, and you've got a good chance of destroying the AC. If not the day you add the refrigerant, then a year down the road, when moisture and air in the system form acids and burn up the compressor.
BUT, in most cases, even if the AC system leaks down enough the compressor won't even engage, there will still be enough residual pressure in the system to create an overpressure and prevent anything from leaking in. You have to use a little common sense here, obviously if had a line break, had a fast and large leak develop or opened a line completely, air and moisture has leaked into the system. As well, if your system has been totally depleted for years, the natural cycle of air pressure with weather may have got to the point where one day the ambient air pressure exceeded what was left in the system and forced some air and moisture into the system.
But, in most cases, where the system is leaking very slowly and your AC was getting weaker slowly over time and now is at the point where the compressor is cycling excessively or won't engage at all, when it was engaging (cycling) a few weeks before, its very likely there is still enough pressure left in the system to keep any air or moisture from leaking in.
Again, your taking a risk, and you really should never service an AC system yourself unless you have the proper set of gauges (hi and low) and know what they mean.
What it comes down to, with AC if you value the system and don't know what your doing, just take it to a pro to be serviced or repaired, your far more likely to destroy the system and cost yourself far more to repair it doing a ham-fisted diy servicing.
If you don't really value the AC and are NOT willing to pay the money for the Pro, take your chances and do it yourself, not knowing what your doing, and you've got a good chance of destroying the AC. If not the day you add the refrigerant, then a year down the road, when moisture and air in the system form acids and burn up the compressor.
The 1lb. cans of freon they sell work okay for topping off a system. If yours is empty or you've had a major leak, I would suggest completly evacuating the system recharging with an ac machine that weighs the amount of freon that enters the system. Much more acuarate way of charging. This is why the manufacterers do it this way. When using guages, many things can effect readings, such as outside temp, altitude, etc. Adding to much can be as bad as not having enough. R-134 conversions are you're best bet for older systems, just keep in mind slightly less R-134 will be required than with R-12. (general rule R-12 charge x .9 minus .25 lb.) seems to work in most cases. Steer clear of the propane based products, there can be a chance of explosion in an accident.
Rick Anderson
NAXJA Forum User
- Location
- Lusby, MD
R-134a has a lower condensation and evaporation point than R-12. This means that a R-134a system needs a larger condenser then a comparable R-12 system, it doesn't need as big of a evaporator though.
So, there are a lot of R-12 system that had overkill condensers, that were bigger than really needed. The larger ford vehicles and many pick-ups fit this category. Unfortunately, NOT many Chrysler's, they had just barely enough of a condenser for R-12. I really don't know about the XJ's that had R-12. If you do an internet search you should find some tables or databases that will spell out the potential for your vehicle as a retro-fit candidate.
BUT, unfortunately, there are some vehicles out there that just won't do well at all after a conversion to R-134a. I'm NOT saying the alternatives refrigerants out there are better in this case, I'm saying if your vehicle is one of the poor candidates for retro-fit, you should consider paying the extra money for a professional servicing with the spec R-12, it will work and be less expensive in the long run.
I have to agree with the Propane/Hydrocarbon refrigerants, they do work well, and it is unlikely, but still its possible to blow yourself up if you use them.
So, there are a lot of R-12 system that had overkill condensers, that were bigger than really needed. The larger ford vehicles and many pick-ups fit this category. Unfortunately, NOT many Chrysler's, they had just barely enough of a condenser for R-12. I really don't know about the XJ's that had R-12. If you do an internet search you should find some tables or databases that will spell out the potential for your vehicle as a retro-fit candidate.
BUT, unfortunately, there are some vehicles out there that just won't do well at all after a conversion to R-134a. I'm NOT saying the alternatives refrigerants out there are better in this case, I'm saying if your vehicle is one of the poor candidates for retro-fit, you should consider paying the extra money for a professional servicing with the spec R-12, it will work and be less expensive in the long run.
I have to agree with the Propane/Hydrocarbon refrigerants, they do work well, and it is unlikely, but still its possible to blow yourself up if you use them.
Mudweiserjeep
NAXJA Forum User
- Location
- tipp city, ohio
Question.....Typically in an older system.....What is the most common leak? O-Rings? I am planning to do the retro fit kit after I take it to have the old taken out. I was thinking of just replacing all the o-rings now before refilling.
Rick Anderson
NAXJA Forum User
- Location
- Lusby, MD
Yea O-rings and shaft seal on the compressor. The oil and R-134a is NOT compatible with some of the older O-ring materials, when retro-fitting you should replace the O-rings with R-134a O-rings made of a material more compatible with the oil and refrigerant.
Lines can leak, the R-134a molecule is smaller than the R-12, requiring a nylon sleeve inside the rubber hose to keep the smaller molecule from diffusing out thru the rubber. BUT, many R-12 hoses had this features by the time R-134a came along, as well, they've found the R-12 molecules often saturated the rubber and plugs all the holes in the molecular structure, so they still seal better than expected with R-134a.
As mentioned, the smaller R-134a molecule and higher pressures associated with the condensing the refrigerant result in any existing leaks usually leaking a little more.
Lines can leak, the R-134a molecule is smaller than the R-12, requiring a nylon sleeve inside the rubber hose to keep the smaller molecule from diffusing out thru the rubber. BUT, many R-12 hoses had this features by the time R-134a came along, as well, they've found the R-12 molecules often saturated the rubber and plugs all the holes in the molecular structure, so they still seal better than expected with R-134a.
As mentioned, the smaller R-134a molecule and higher pressures associated with the condensing the refrigerant result in any existing leaks usually leaking a little more.
Some manufacterers started using the neopryne seals well before R-134. If you have these you won't have to switch.( they will be colored as opposed to black rubber ones. Unbolt your compressor and tip it over to drain oil. And like Rick said replace the orifice tube, and even the accumulator if you really want to do this right. Vac it down extra long (1/2 hr to 1 hr). make sure you put in the right amount of oil too. I usually poor some of it directly into the compressor than let the vacuum pull in the rest...good luck!
momma's xj
NAXJA Forum User
- Location
- mtn home idaho
so what if the high side has lots of pressure & nothing on the low side?
momma's xj
NAXJA Forum User
- Location
- mtn home idaho
so, dead thread...is it the compressor or expansion valve?
... bringing it back to the top will only serve to inform people who've never seen it before.
- Location
- MilkyWay Galaxy
momma's xj said:
Could be either or neither. Could be clogged anywhere, crushed tubing, hose ID failure, cloggged filter/dryer, but the expansion valve is the usual suspect.
I had that problem recently, turned out the AC shop that replaced my hoses screwed up and oversoldered a tube to tube joint and filled it up with metal close to the condenser. I did not find their mistake until hours of work later replacing the expansion valve and filter dryer, needlessly. I made the mistake of assuming a professional AC shop did not make a stupid mistake.
After 2 bad guesses as to what was really clogged I opened the entire system and used an air blow gun to test every single part for flow.
Saudade,
Some threads are like cats, they have multiple lives! LOL. Seems this one is not quite !!!1.
This thread seems to go dead in winter and usually drifts back up in spring/summer. In my earliest posts - I suggested to read/study and/or get some training about AC systems. It's really the best way to "know" - we're just talking/boasting here and not trying to make everybody into an AC tech.
Know your limits (good for you splitz) but if you find it fascinating enough to invest study time you'll never regret it and you'll eventually be able to save a nice chunk of money and impress the wife. (Same thing can be said about Electronics training.)
btw - I did use some R22 in an R12 system many, many years ago. It was my own car and I simply didn't have anything else handy. It worked but iced-up if I didn't cycle it a few times during use. Not recommended but it did cool until I was able to R&R leaking compressor.
Blends are drag because with a slow leak they separate and purge at different rates over time leaving you with a different mixture of Freon type in your system than you started with....
I've had good results with the R12-R134 conversion kits. Did my XJ in an AZ, Auto Zone lot nearly 10 years ago, added one can since and it still works fine to this day.
Know your limits (good for you splitz) but if you find it fascinating enough to invest study time you'll never regret it and you'll eventually be able to save a nice chunk of money and impress the wife. (Same thing can be said about Electronics training.)
btw - I did use some R22 in an R12 system many, many years ago. It was my own car and I simply didn't have anything else handy. It worked but iced-up if I didn't cycle it a few times during use. Not recommended but it did cool until I was able to R&R leaking compressor.
Blends are drag because with a slow leak they separate and purge at different rates over time leaving you with a different mixture of Freon type in your system than you started with....
I've had good results with the R12-R134 conversion kits. Did my XJ in an AZ, Auto Zone lot nearly 10 years ago, added one can since and it still works fine to this day.
Like Mike said - it would seem clogged. If it were me, I would measure the temps and compare to pressures but either way it sounds like it will need to be opened.
