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Old 06-15-2020, 06:35 PM   #1
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Dash Air is blowing ambient air

Last weekend I drove my 2018 MADP from Maryland to Nappanee, but my dash air would only blow ambient temperature air. I last used the coach in March, but donít recall how well the dash air was working. I donít recall there being an issue, but I may not have used it.

I had the dash air set to the highest speed setting and the AC button was depress and lit. I also tried fresh and recycled air with no difference. The compressor runs when the AC is turned on. It did not appear to be cycling. My thought is that there is refrigerant in the system as the low pressure switch would otherwise stop the compressor from running.

Iíve started researching the Evans troubleshooting documentation. I started the coach this afternoon and ran it at 1500 rpms. The dash air was blowing ambient temperature air (measured with a thermometer placed at vent opening). After 8 minutes I shut things down. I checked all the lines at or near the Evans unit and they were all at ambient temperature. There was some hissing sounds coming from the Evans unit, but it sounded normal to me based on sounds that I have heard from other AC units in the past. My understanding is that since the engine was cold when I started this test, the problem is not the hot water valve leaking issue that Iíve read about.

I donít (yet) have any pressure gauges to test the refrigerant levels. Iím wonder what else I can/should check before find a professional to take a look at it. Thanks.
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Old 06-15-2020, 06:46 PM   #2
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It is possible to have low freon and not be low enought to trip the low pressure switch. Are the vents/doors operating as they should? Next best step is a pressure reading. Poor mans check but if you can start feeling lines if you can. Hot gas from the compressor, change to close to ambient liquid line going to the evap, cold sweating after the exap valve and cool possibly some sweat going back to the compressor. After saying all that you may not have access to some of it
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Old 06-15-2020, 07:19 PM   #3
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The control valve for directing where the air blows works as it should. The coachĎs front cap has hydraulics and extends for generator access. This provides great access to the AC components.

The Newmar tech (who was working warranty stuff) gave me a quick education on what to look for. He pointed out the lines to check. They are all at ambient temperature which is what has me baffled. Given this, my feeling is that either the compressor isnít working correctly or the refrigerant is low. The compressor is engaging when the AC is turned on. My thought was that the refrigerant level was okay given the low pressure value wasnít stopping the compressor from running, but it sounds like that isnít necessary the case.

The tech also mentioned that the system has dye in it. Can I use a generic UV flashlight to check for the dye?
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Old 06-15-2020, 08:30 PM   #4
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Sounds very strange, no differences in line temperature at all would mean no work being done by the compressor. Really need gauges. You said the compressor is engaging. Is there any way you can short or open the low press switch to see if the reaction of the clutch changes. Goes from engagement to no engagement? Would be VERY strange but is it possible the clutch plate is engaging but the actual compressor is not. I know it sounds way out there but 30+ years in the oil industry both on shore and off I have seen some weird stuff. Had a pump that had no output one time. After tearing it down I found the small half moon key on a tapered shaft had sheared. No squeal or sound at all as would be expected
+. About any UV light should work
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Old 06-15-2020, 08:41 PM   #5
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Might be a clogged or stuck modulation valve. Give it a tap with a hammer. Once you get the gauge set then it will be easier to tell what the problem is.
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Old 06-15-2020, 09:01 PM   #6
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Dash Air is blowing ambient air

Quote:
Originally Posted by kenwyatt View Post
No squeal or sound at all as would be expected

I had a significant squeak in the engine compartment a few weeks ago. I removed the alternator belt and found the source of that squeak. Spartan covered replacing the alternator. I had that done a few days before we left for Nappanee. Iíve noticed that I still have a slight squeak. It could be coming from the new alternator (I would hope not), or the compressor. I need to pull the belts off and manually check by turning the pulleys.

This is the noise that led me to having the alternator replaced.

https://www.dropbox.com/s/4mvf0cmem1...queak.MOV?dl=0

I guess I need to buy some gauges.

The Newmar tech did show me where to short the low pressure switch, so I can give that a try to verify that it working correctly.
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Old 06-15-2020, 09:14 PM   #7
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Quote:
Originally Posted by flyboy013 View Post
I had a significant squeak in the engine compartment a few weeks ago. I removed the alternator belt and found the source of that squeak. Spartan covered replacing the alternator. I had that done a few days before we left for Nappanee. I’ve noticed that I still have a slight squeak. It could be coming from the new alternator (I would hope not), or the compressor. I need to pull the belts off and manually check by turning the pulleys.

This is the noise that led me to having the alternator replaced.

https://www.dropbox.com/s/4mvf0cmem1...queak.MOV?dl=0

I guess I need to buy some gauges.

The Newmar tech did show me where to short the low pressure switch, so I can give that a try to verify that it working correctly.
If the compressor clutch is engaged (you can see the center spinning when engaged - it has "1CJC..." printed on it in your .mov), then you don't need to short the lower pressure switch - because it already is (by the existence of Freon). Remember, the belt spins the outside of the clutch. When the clutch is engaged, it spins the compressor (the center section of the clutch which is connected to the compressor shaft). You should also be able to hear it engage. Have someone turn the AC on / off when you are in the back watching and listening.

If the compressor is spinning an the tubes are all the same temp, then the compressor is shot and not making any pressure, or there is a restriction in the system and no flow. If no flow, then the odds are the dryer broke up on the inside and the dessicent found it's way to clog the modulation valve. This will be obvious if there is freon, but no flow and when the system is discharged and taken apart, then you will see the pellets in the hoses and valve In side. System then has to be taken all apart and flushed. Dryer and valve replaced.
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Old 06-15-2020, 09:56 PM   #8
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Dash Air is blowing ambient air

Well when I had my wife turn on the AC, I definitely saw the clutch engage. The slight squeaking that I was hearing didnít seem to come and go with the compressor being engaged, so it could be something else squeaking, or not. Iíll pull the belt tomorrow. Definitely, no temperature changes in the lines, so that makes sense that either the compressor isnít doing itís job or thereís a clog, but then I would have expected the low pressure switch to cut the compressor off.

Between this dialogue and reading the Evans Service Manual, Iím definitely becoming more knowledgeable about the dash AC system...

Iíll give Spartan a call tomorrow. The compressor and the lines to the front of the chassis are under warranty for another 5 months. The Evans components are no longer under warranty. Weíll see how this works out.

Thanks.
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Old 06-16-2020, 06:27 PM   #9
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The dash AC in our new Dutch Star is blowing at outside temperature. The coach is a the Spartan Service Center now so I will report back on what they say.
When I set up the appointment it sounded as if ours is not the first one they have looked at.
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Old 06-18-2020, 05:29 PM   #10
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Warm dash air has been discussed before and redbaron found the problem that's been around since early 2003.
The Evans control valve was not installed correctly, thread is found in section with all EVAN's info.
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Old 06-19-2020, 01:16 PM   #11
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Quote:
Originally Posted by ShelbyTom1 View Post
The dash AC in our new Dutch Star is blowing at outside temperature. The coach is a the Spartan Service Center now so I will report back on what they say.
When I set up the appointment it sounded as if ours is not the first one they have looked at.
Any update from Spartan?

I got my gauges in the mail yesterday and connected them up. Below is the picture of the readings. I have a slight negative pressure on the low side and about 85 psi on the high side.

Click image for larger version

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I was looking various troubleshoot guides and it seems like the diagnose may be Refrigerant does not circulate. Although one of the indications of this problem is "Frost or condensation on the front and rear pipe connections of the receiver dryer or expansion valve". I'm not seeing any frost.

This issue is caused by:
  • AC system is blocked by contamination or ice
  • AC system is shut off by defective expansion valve or temperature sensor
  • AC line from evaporator to compressor has kink in the line

Any suggestions or guidance before I take it to the shop would be appreciated.
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Old 06-19-2020, 06:43 PM   #12
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Looks like a blockage. Likely the metering valve if anything. I would decharge the system and disconnect the valve and look for debris. If any is found the whole system should be disconnected and flushed. You might as well order a dryer and valve now.

The compressor is trying to pump as it is going negative. Don't run it that way or it can kill the compressor.
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Old 06-21-2020, 12:44 AM   #13
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Dash Air is blowing ambient air

Quote:
Originally Posted by flyboy013 View Post
Any update from Spartan?.....
Newmar would not let them fix it because it was aĒNewmarĒ issue so they sent me to a Thermo King service center and they have to ordered a new Filter Receiver Drier and metering valve
Apparently there was a blockage.. the mechanic said it happens when there is some contamination in the lines during installation.
Should get the part next week so I will let you know how it turns out
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Old 06-29-2020, 03:38 PM   #14
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Dav L.,

I dropped off my coach today to have the dash AC worked on, but it sounds like it may be a few weeks before I get it back due to other work they have and given that they may need to order parts (Expansion Valve).

I'm looking for Evans documentation on the system. I've found this manual, but it appears to only go up to year 2017. My coach is 2018. My guess is that it's all the same, but I'm not really sure. Newmar had listed the Evans dash air model number as RV202058, but I'm not finding much when searching Google for this. I did find a 2 page document with some part numbers, but not much else.

I found this document on the Newmar website. The Evans website doesn't seem to work. Do you know where I can find a service manual that covers 2018? In reading some old posts on your MA, it looks like you replaced the expansion valve. From Amazon if I recall. Did this work OK for you? I recall bruceisla providing quite a few other links.

Also, from the manual it would appear that my 45' 2018 MADP/Spartan would require 8 lbs of refrigerant. Does that sound right? I looked at the bottom of page 37 of the above manual and it lists 8 lbs for "Spartan Rear Mounted Fin & Tube Condenser, Side Radiator w/ No Elect. Fan, >=450 Hp, 43’ or Longer Chassis". I think that's me!

Thanks for the help.
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