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08-03-2020, 12:08 PM
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#15
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Senior Member
Join Date: May 2017
Location: Metamora, MI
Posts: 5,518
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Look for fine dirt accumulating near fittings. Telltale sign that's where the freon leak is, because the oil is also leaking out which attracts the dirt.
Worse case, pull new hoses in with the old ones as the pull cord (disconnect all tie wraps, hangers first) and replace the dryer and Vac and recharge. You can also pull a strong string to pull the new hose in. Once the old hose is out, you can take that to a auto parts store to build a matching hose (length / diameter / right ends crimped on). Unlikely that's where the problem is. RV air is much easier than auto air. Same parts and technology and tools, but easier to get to the devices.
Sniff test the drain from the evaporator water...might be a evap leak. If you smell oil out of the vents, that's another indicator.
Replace the schrader valves no matter what. High percentage of leaks. When you remove the covers, listen for a very brief Hiss that indicates the valve is leaking.
If you are a good DIY'r and have access to AC tools (gauges, vac pump, valve remover etc) then this just takes clear systematic diagnostic time to root cause.
__________________
2002 Newmar Mountain Aire Limited 4370 w/ Spartan K2 and Cummins 500hp
ASE Master Certified (a long.....time ago...)
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08-06-2020, 09:53 AM
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#16
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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I can't seem to find the Schrader valves around the compressor? I can only find that one by the evaporator on the suction line? Anyone have any tips on a high side connector?
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2006 Newmar Mountain Aire 4301, Cinnabar
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08-06-2020, 10:20 AM
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#17
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Senior Member
Join Date: Dec 2019
Location: Alberta
Posts: 1,976
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Hissing noise at the TX is a sign of low refrigerant or a condensing problem.
You mentioned 200 PSIG for a high side. Maybe. Condensing pressure is related to ambient temp. So for 200 PSIG you would need an ambient temp of 100f.
You take the ambient temp, add 30f to it and read off the pressure on a pressure temperature chart. So at 72f I would expect a pressure of 130psig.
Make sure when you are working with refrigerants that you wear safety glasses. This chemical cocktail can be dangerous.
__________________
Jeff and Annette Smith. Sparky, lemon Beagle.
2022 Chevy Equinox RS.
2007 Dutch Star
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08-06-2020, 01:06 PM
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#18
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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I have to find the darn high pressure Schrader valve! LOL. I will post before and after pressures here to help others ....
__________________
2006 Newmar Mountain Aire 4301, Cinnabar
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08-06-2020, 01:15 PM
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#19
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Senior Member
Join Date: Dec 2019
Location: Alberta
Posts: 1,976
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Quote:
Originally Posted by ColoradoBnd
I have to find the darn high pressure Schrader valve! LOL. I will post before and after pressures here to help others ....
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Usually. I say usually on the discharge line from the compressor to the condenser. May also be on or near the receiver drier. Hope this helps.
You are doing great.
__________________
Jeff and Annette Smith. Sparky, lemon Beagle.
2022 Chevy Equinox RS.
2007 Dutch Star
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08-07-2020, 05:21 PM
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#20
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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I looked again today. Very strange to me because I have done some car AC work. Right out of the compressor and going to the condenser are the crimped rubber hoses. No sign of Schader valves. I guess I’m just going to pump 12 oz into the valve up by the evaporator after checking the pressure. I do have a refrigerant scale, so I can measure what I put in. Unless you guys have better places to look.
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2006 Newmar Mountain Aire 4301, Cinnabar
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08-07-2020, 10:41 PM
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#21
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Senior Member
Join Date: May 2017
Location: Metamora, MI
Posts: 5,518
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Quote:
Originally Posted by ColoradoBnd
I looked again today. Very strange to me because I have done some car AC work. Right out of the compressor and going to the condenser are the crimped rubber hoses. No sign of Schader valves. I guess I’m just going to pump 12 oz into the valve up by the evaporator after checking the pressure. I do have a refrigerant scale, so I can measure what I put in. Unless you guys have better places to look.
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There is "definitely" high and lower pressure ports. Probably two pairs (front and back). You know that they typically have a threaded plastic cap over the top of them? One will be on one side of the modulating valve and the other on the other side of it.
By chance had a hose been replaced before? Long shot, but maybe the replacement hose didn't have the port on the hose it replaced...
12 ounces is nothing for most all RVs. Just enough (maybe) for the clutch to engage, but not enough to get cold. You also should Vac the system down first for a few hours. If the system has been opened (zero freon), then replace the dryer component first (must do).
__________________
2002 Newmar Mountain Aire Limited 4370 w/ Spartan K2 and Cummins 500hp
ASE Master Certified (a long.....time ago...)
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08-08-2020, 07:47 AM
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#22
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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Found both of them, but there are none in the back (kind of surprising to me). Nothing by condenser or compressor. Don't know on the hose change. High side is by the dryer in the coach front compartment and low side is on the evaporator inlet. Pics to help others .....
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2006 Newmar Mountain Aire 4301, Cinnabar
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08-08-2020, 12:10 PM
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#23
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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Does anyone know where the expansion valve is? Is it built into the Evan’s unit somehow??
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2006 Newmar Mountain Aire 4301, Cinnabar
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08-15-2020, 11:52 AM
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#24
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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Here is the followup to help others. Starting suction pressure was 0 and discharge was 50 psi. These 134a quick connects are sweet! No more frostbite. LOL. Put in 1.6 lbs of 134a and the suction came up to 39 psi and discharge to 200 psi at about 75 F ambient. That charge yielded about 21 F differential across the evaporator . Textbook results versus the Evan's booklet. Thanks to all that helped and I hope this helps others.
Now time to find that leak!
__________________
2006 Newmar Mountain Aire 4301, Cinnabar
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08-31-2020, 07:39 PM
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#25
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Senior Member
Newmar Owners Club Spartan Chassis
Join Date: Apr 2017
Location: Eden, UT
Posts: 418
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Well, didn’t last for long. Lost refrigerant in several days to the point where the clutch wouldn’t engage. Are there any techniques other than wasting another 1.6 lbs of refrigerant with dye injection to find the leak?
__________________
2006 Newmar Mountain Aire 4301, Cinnabar
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09-01-2020, 06:35 AM
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#26
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Senior Member
Join Date: May 2017
Location: Metamora, MI
Posts: 5,518
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If the system needed freon, there is a leak. Should have fixed the leak first time. That being said, now you put dye in the system. And look for dirt collecting at a fitting that may indicate where the leak is. Replace the schraeder valves (where you connected the hoses to the system as they are common leak points). Listen for hiss when you remove the protective caps which is evidence that the valve is leaking. Listen for hissing (if it took several days then it's not a huge leak) at lines / connection points.
There is leak detection equipment that looks for the existence of freon in the immediate air.
Good time to pressure wash the entire motor, AC system components so it's more evident where dirt collects for the next time.
Get a receiver / dryer for the next repair attempt and replace it. You will need a AC vacuum to evacuate the system once it has been opened up.
__________________
2002 Newmar Mountain Aire Limited 4370 w/ Spartan K2 and Cummins 500hp
ASE Master Certified (a long.....time ago...)
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