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On a trip I found my AC evaporator was icing up and was informed it was low on refrigerant,  refrigerant was added and it did not solve the problem, so I continued on with trip using the house AC to keep cool as I did not want to go from AC shop to AC shop on my trip. Plus is was not that warm out.

Being overly impressed with my diagnostic skill's I assume I know what the problem is or may be. Took it too a mechanic friend (not an AC tech) he checked it and kinda confirmed my diagnostics but said to take it for proper testing.

I don't want it diagnosed, I want the system evacuated so I can replace the expansion valve and make sure the thermister was not dislodged.  I go to the local AC place and they insist on doing a free diagnostic check and will evacuate the system for me.

So they do their check and hand me an estimate for $1212, holy bad dung Batman.  No wonder no one gets their AC fixed!  When I balked at the bill, he far too quickly added that they could trim some of the fat off it. 

 


They tell me the system has been overcharged and blown the front AC seal and the compressor has a bad leak and needs to be replaced.  The over charging is very possible, but how do I have an over charged system and a bad leak.  I don't know much about AC, but this sure don't smell right??  Looking the estimate over they want to replace all the parts and clean the others including my wallet!

Flush a condenser, evaporator and lines for no reason, replace the evaporator and charging ports. All the while saying (does not include air conditions system recover, evacuate and recharge) 3 times.

So I take it apart and now I start looking around on the net and asking questions. I have went about this all wrong but my thermister is not laying on the bottom of the case, which I could have found out with proper diagnostics.  As long as it is apart I am replacing the expansion valve and pressure switch, which might be a problem or might not.  I could have tested for this before I did anything else and saved myself some work and $$$$

In the meantime I have bought a UV light and glasses and can find no leaks anywhere. Particularly on the compressor with a large leak. The original PAG has dye in it so should be obvious.

Keep an eye peeled for the rest of the story.

AC bill.jpg

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  • 2 weeks later...

While I had this apart I was able to test the thermister, I replaced the pressure switch and the expansion valve as have no way to test. Also replaced the dryer as I had a spare one sitting.   Put vacuum on overnight and showed no signs of leaks.   Vacuum is not a sure sign of no leaks as is a pressurized system and could not access nitrogen for testing.

I installed refrigerant, but did not have the #'s from 1st install. Chart called for minimum of 16oz 134a so I stopped at 17 with 50° vent temp.  So I can observe before adding more.   The pro's told me when dealing with an unknown system to let the system equalize before looking for sweet spot on refrigerant fill.

I do not see any leaks and the evaporator is no longer freezing.  In the meantime I found that last time I added 20oz of 134a and achieved a vent temp of 41° with the temp in the 90's.  So now know about where I should be.

Looking more and more like NAPA shop needs to buy gun's and masks for employee's. 

 

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  • 3 weeks later...

Looking at your low and high pressure you could get away with adding a smidge more freon. Bring the rpm up to 2k or close and see what the low side drops off to. If the compressor cycles you can add more till it stops

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On 9/3/2017 at 11:18 AM, 85shasta said:

Looking at your low and high pressure you could get away with adding a smidge more freon. Bring the rpm up to 2k or close and see what the low side drops off to. If the compressor cycles you can add more till it stops

I did add 3 oz of 134a pressures are now more inline with charts and now have an issue with evaporator freezing. Which is where I was before.  

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When you deal with 134 you need to have an ambient temp to pressure chart to properly charge the system. The sock in the drier is suspect you said it was one you had that leads me to believe it was sitting around collecting moisture. Overpressure can cause evap freeze up. Low air flow leaves etc. in the intake duct also

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2 hours ago, Maineah said:

When you deal with 134 you need to have an ambient temp to pressure chart to properly charge the system. The sock in the drier is suspect you said it was one you had that leads me to believe it was sitting around collecting moisture. Overpressure can cause evap freeze up. Low air flow leaves etc. in the intake duct also

Drier was brand new, sealed.    Pressures are in line with AC charts, system has been apart and everything is clean.  

I did replace the blower motor and fan,  it is possible it is the wrong one and not pushing enough air?

Thermister was tested as per FSM and is within spec's, shouldn't the thermister turn off clutch if system is icing up?

Thanks for the response always appreciated.  

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