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A/C issues, need help before heat hits!

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  #71  
Old 05-26-2012, 11:08 PM
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Smile you saved big time

you saved big time they would of replaced everything you did but they would of tacked on Labor you did the labor.

It just took you longer thats all you learn as you go and we all screw up the first time and get frusterated.

Have you done your ball joints yet? Now thats hard and very frusterating just wait.


Plane well and have patience especial if it’s your first try at a new project
 
  #72  
Old 05-26-2012, 11:37 PM
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not yet. we will work on both uppers and lowers this summer with my dads friend, its gonna be a p.i.t.a.
 
  #73  
Old 06-15-2012, 06:03 PM
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First off as with most things it takes years of practical experience to obtain all or most of the knowledge necessary to troubleshoot a/c systems in general. They are just a bit more complex in nature than most can easily understand. From the looks of your gauges I'd say it's possible for there to be a number of issues and you will need to go to square one to begin. First thing is to completely purge the system of all pressure and then vac the system thoroughly to boil off all non-condensibles picked up when your system was pulling negative pressure on the low side due to low charge. The system normally has enough refrigerant to keep both high and low side in positive pressure until a leak occurs. Once moisture/dirt/whatever is pulled it's a matter of starting from scratch. Incidentally, I have several degrees in both engineering and a/c troubleshooting/repair (just putting that out there so you can assume confidence in my word). Pressure reading will be skewed without a pure charge of the refrigerant your system calls for (air, water, refrigerant boil at different temperature/pressures). No one can determine anything without doing the purge and recharging. Now that you've done that your readings should be in the proper range for the particular type refrigerant. R134A may produce something like 50 low/250 high or thereabouts depending one outdoor temp, inside air speed, system condition, etc. Write me back once you get to this point. If you have a leak you may do what millions of red blooded Americans do and that is to add more every so often. Not kosher but it works and is cheaper and less hassle than leak checking/repairing. If the leak is significant enough you will want to do a leak check. Never use additives such as red dye or leak sealer as these WILL damage vital components inside the system such as plugging filter screens and rubbing your compressor piston the wrong way. Sometimes you can spot oil near a leak but in my vast experience (over 40,000 systems to date) I rarely see oil where the leak is as it evaporates quickly. If the leak is significant you will not only see oil but you will hear the hiss!! Nuf said about that issue. A good leak detector electronic or my favorite, a halide detector is optimum. Problem is some components are not visible or easy to get to. O-rings are the number one culprit in auto a/c so I recommend a change out of them. This will require another purge and after repair a thorough vac of the system with a high vacuum pump. Your pump should be able to draw down to 5 microns or less per million. You can do a leak check at the point where you have finished vac'ing the system. Just shut the valves on your manifold set and watch to see if there is movement on the compound gauge (low side gauge). It should be down below 25 inches of mercury (hg) and stay there. Remember a pure vacuum is around 28.27 inches of mercury. If the needle moves upwards either you have a leak or have things still boiling off inside the system such as water which boils a little slower at this vacuum level than r134a. (water does boil at this vac/pressure at normal temps) So try to vac some more and check again to see if the needle holds. I've seen some system where no one could ever find the source of a minor leak for the lifespan of the unit and constant refil was necessary. Once I saw a 125 lb canister of refrigerant permanently located next to a system with a hose connecting the two so the maintenance man could just turn on the tank valve periodically to adjust the charge (atop social security building in Baltimore - no lie. and they preach to us about leakes). In other words small leaks are sometimes the cost of keeping cool and we must learn to live with them. Large leaks are easier to find and repair. Like I said, write back if you need more advice. Could be compressor or metering device or even fan or dirt on coils etc.
 

Last edited by mellowde; 06-16-2012 at 10:39 AM.
  #74  
Old 06-15-2012, 06:21 PM
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Incidentally, the changeout of metering device (restrictor tube on most dodges) is usually unnecessary. Moisture mixed in with refrigerant forms ice at the end of the metering tube (the coldest place in the system) which operates below freezing thus causing a blockage. I don't think this is Brian's problem though based on the pressure readings (blockage would normally cause low suction and high head pressure). If moisture is present though it can be boiled off with a vac pump. The only time I can think of when it's necessary to replace the restrictor tube is if either the diffuser screen or filter screen inside it is blocked with leak repair compound found in some cans of r134a. Most times the screens can be scraped and cleaned (generally metal shavings are the only items floating free inside a sealed refrigerant system). If it's been sucking below atmosphere (negative pressure) long enough and moisture is present it can form mold on the screens. I've only ever seen this personally one time in the many times I've done service so it's highly unlikely. The restrictor itself is a capillary tube which meters the flow of refrigerant by resticting the amount that can flow through the tube by it's small diameter. Blockages inside the tube are almost non-existent unless someone crushes the tube manually. The filter screen is located up front of the restrictor tube thus preventing blockage by dirt or metal shavings. I personally have never had to replace a restrictor tube. And that is in over 20,000 auto units. The manual tells you to replace if blocked but they want you to buy new parts. 99.99% of blockages here are caused by moisture freezing which is handled by vac'ing the system to remove moisture.
 
  #75  
Old 06-15-2012, 10:37 PM
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thank you for the response! although i never posted that i had got this thing straighted out only to 98dakaz in a private message, but my ac has been holding great for the past 4ish weeks with temps at 45f with it being 85f outside. it was a bummer to see my mpg drop!

now i read through your post and thought the 125lb can was hilarious!
 
  #76  
Old 06-16-2012, 11:01 AM
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That's good change in air temp over the evap coil. Is that at high speed fan? Mine gives me about 35 deg F change over the coil at high speed (97 in/62 out). And increases to 40 deg change at next lowest fan setting. I can get a couple of degrees at lower setting on the fan but not enough flow to cool the back seat quickly. I found that during the spring when pollen is airborn the change drops off some as the pollen coats and insulates the condenser coil (and probably the evaporator coil). A trip to the car wash helps. Ever so often I have to take a brush to the cond coil to clean bugs off. My truck has 4 coils up front (radiator, oil & tranny cooler, and the condenser coil.) The cond coil has a separate electric fan mounted behind it to pull air through which helps at idle and slow speeds. Dodge really did it right. Some vehicles rely on air over the cond coil when moving. The thermister probe on the evap coil is sheer genius. It determines whether to shut off the compressor clutch. My car (kia) has an expansion valve and a high pressure cut off if the head pressure gets too high. I'm not sure if you understand all this but the thought that went into the design of the dodges is beyond what is normal. The compressor is protected against really high pressure situations the way the a/c is designed. Just one of many features I found on this dodge that amaze me. The battery has a heater under it to help avoid cold start drain. I'm using the original battery 6-1/2 years old and over 90,000 miles. I could go on. Dodge is truly the best designed US truck on the market.
 
  #77  
Old 06-17-2012, 01:04 AM
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got the temp while fan was on low.

Originally Posted by mellowde
Dodge is truly the best designed US truck on the market.
i have thought the same thing people attempt to bash on my truck and say ford is superior which is a joke.

it has its moments like the ifs crap, then again i have mine lifted and am gonna have those issues.
 



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