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Gjac

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Posted: 07/27/21 01:00pm Link  |  Quote  |  Print  |  Notify Moderator

rgatijnet1 wrote:

I think the needle is actually called a schrader valve.
When you say you see bubbles coming out of the Schrader valve that could be where your leak is coming from. You can tighten that valve with a tool. Some valve caps have that tool built in the top of the cap, either way these are $2 or less.

buystockinfun

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Posted: 07/30/21 06:44am Link  |  Quote  |  Print  |  Notify Moderator

Lol, I would think that to some extent just like in propane 5 gallon propane tank holds less propane then a 7.5 gallon. I would think the lines would increase the capacity somewhat but probably not double LOL so I get what you're saying. Without ripping the system apart on the highway basically I'm going to have to wait until I get home I guess. I still don't really understand the whole expansion valve thing and somebody was mentioning kind of screen and taking something and cleaning it I don't know if that means the system needs tore apart to do that. I know replacing the dryer and would involve tearing it apart as far as I could tell here the fittings are not removable as I see some places sell like green o-rings but it doesn't appear that this system is removable in terms of those fittings except for whatever that little valve is that looks like a tire valve. I have a feeling the dryer isn't removable either unless it's cut or something from what I can tell everything looks all soldered or welded or whatever you want to call it. I'm pretty sure I'm pretty primed to get ripped off at an AC shop if I'm not careful. On a side note I've never seen the compressor turn off while the engine was running I guess I should check to see if it turns off when the air conditioning knob is on off but it never turned off when I was filling it or whatever I guess maybe because of the pressure on the low side is what it is I don't know so there's a few things here that I don't totally understand. Is there anything I can do with that screen with the closed system? It almost sounded like I could but I don't know then I still have to find the stuff. Thxs

dougrainer

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Posted: 07/30/21 07:07am Link  |  Quote  |  Print  |  Notify Moderator

There is NO screen you remove and clean. YEARS ago(35 to 45) GM and others had a orifice tube that had a screen that you could remove and clean/replace IF it caught debris caused by a failed component in the AC system. An expansion valve just opens and closes its orifice to meter the flow of coolant to get the heat removal done. You do NOT have to replace the dryer or tear the system apart. The fact you get 63 air shows the system is operating and you just need to do as I stated. Drain the system and install the 4 lbs and then see what happens. A dryer is usually replaced when you have had a catastropic opening of the sealed system or if the system has been opened to the air due to a drain and hole for some time. The dryer has a dessicant and needs replaced when that fails due to exposure to air. So, at this point you do not have to replace anything other than the 134a. Doug

PS ALL the components are replaceable

* This post was edited 07/30/21 07:13am by dougrainer *

dougrainer

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Posted: 07/30/21 07:12am Link  |  Quote  |  Print  |  Notify Moderator

To your LP tank statement[emoticon] A 20 lb tank holds 5 gallons FULL. BUT you only fill to about 4.6 gallons liquid due to expansion and need for vapor. A 30 lb holds 7.5 gallons, but only fill to about 7.2 gallons. Fun Fact. Doug

RLS7201

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Posted: 07/30/21 09:54am Link  |  Quote  |  Print  |  Notify Moderator

buystockinfun wrote:

Richard, thanks for the information on the compressor I didn't realize that that was the method to figure out the exact type of oil. Probably saw why some oil was added to begin with. Interestingly an RV dealer told me that they've seen systems take up to 10 pounds though I believe Doug said my system should only hold 4 lb.

As far as the dryer so you're saying I may need to replace the dryer. I'm supposed to use a wire to replace the dryer or are there fittings that need separated in the system evacuated and all of that? Or maybe you mean to do something with the expansion valve screen. It's my understanding that's all sealed and you would need to replace the expansion valve but is there a way to unclog it or do something with this screen with a small wire? Not sure I completely follow that.

When I say needle now I guess I mean is it a valve stem you know like the little valve stem thing inside of a air fill they look the same in the inner tube or your automotive tire as they do inside of those air conditioners the connector for the low and high side.

Thanks again so much


Let me try this again. The inlet of the expansion valve has a screen that some times gets clogged. After depleting the system, you take the hose fitting off the inlet side of the expansion valve. Look closely inside the valve and you will see a screen. If you see debris, remove the screen with a small bent, pointed wire and clean it. If there is debris in the system then the receiver/dryer will need too be changed, as it also filters the system. The receiver/dryer is a round tank with fittings on both sides, at the top. Remove fittings and loosen the clamp.
The needle that you mention is a schrader valve, very similar to a schrader valve in a tire.
As far as the refrigerant capacity of diesel MH systems, the location of the condenser is the major contributing item. If the condenser is in the rear, then the liquid line runs almost the full length of the MH. If in the front, then the liquid line is much shorter and less refrigerant is required.
To address the word "FREON". Freon is a DuPont trade mark and does not describe any chemistry. R12 & R22 are not FREON, they are dichlorodifluoromethane & difluoromonochloromethane. Where as 134A is Tetrafluoroethane. The word "refrigerant" covers the whole array of chemistry and is the word most normally used by trained technicians.

Richard

* This post was edited 07/30/21 10:09am by RLS7201 *


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buystockinfun

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Posted: 07/30/21 10:00am Link  |  Quote  |  Print  |  Notify Moderator

Well the condenser is in the front I think with the compressor in the back. The compressor doesn't have the fluid in and as well the refrigerant? I thought that was through the entire system but anyway. I did find the capacity and I did find the dryer which are in the front and I figured out how to attach pictures it's just advanced posting I'll throw in a few pictures of a bunch of parts that I have no idea what they are other than maybe the dryer. Okay maybe not I don't understand why it wants the URL for the picture don't know what that means I thought I could just attach a picture.

buystockinfun

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Posted: 07/30/21 10:01am Link  |  Quote  |  Print  |  Notify Moderator

[image]

buystockinfun

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Posted: 07/30/21 10:03am Link  |  Quote  |  Print  |  Notify Moderator

This is real hard to do without pictures I mean kind of weird that you can't put pictures on this website very easily most people have pictures like they take that they want to just post rather than like Do I have create a web page to send a picture?

There are some caps on the dryer I don't know what they are for... Etc. Pics would be nice to be able to post.

dougrainer

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Posted: 07/30/21 10:08am Link  |  Quote  |  Print  |  Notify Moderator

RLS7201 wrote:

buystockinfun wrote:

Richard, thanks for the information on the compressor I didn't realize that that was the method to figure out the exact type of oil. Probably saw why some oil was added to begin with. Interestingly an RV dealer told me that they've seen systems take up to 10 pounds though I believe Doug said my system should only hold 4 lb.

As far as the dryer so you're saying I may need to replace the dryer. I'm supposed to use a wire to replace the dryer or are there fittings that need separated in the system evacuated and all of that? Or maybe you mean to do something with the expansion valve screen. It's my understanding that's all sealed and you would need to replace the expansion valve but is there a way to unclog it or do something with this screen with a small wire? Not sure I completely follow that.

When I say needle now I guess I mean is it a valve stem you know like the little valve stem thing inside of a air fill they look the same in the inner tube or your automotive tire as they do inside of those air conditioners the connector for the low and high side.

Thanks again so much


Let me try this again. The inlet of the expansion valve has a screen that some times gets clogged. After depleting the system, you take the hose fitting off the inlet side of the expansion valve. Look closely inside the valve and you will see a screen. If you see debris, remove the screen with a small bent, pointed wire and clean it. If there is debris in the system then the receiver/dryer will need too be changed, as it also filters the system. The receiver/dryer is a round tank with fittings on both sides, at the top. Remove fittings and loosen the clamp.
The needle that you mention is a schrader valve, very similar to a schrader valve in a tire.
As far as the refrigerant capacity of diesel MH systems, the location of the condenser is the major contributing item. If the condenser is in the rear, then the liquid line runs almost the full length of the MH. If in the front, then the liquid line is much shorter and less refrigerant is required.

Richard


While you can remove that screen, it is much easier to replace the Valve. Also, that screen will only get clogged if you have a problem with the Compressor failing and throwing debris thru the system. Also, when I State Capacities, that is NOT my guess but the specs from the maker of the AC system for a Roadmaster chassis. I have the specs for Roadmaster/Spartan/Freightliner/Ford/Workhorse/Chevy, Gas and Diesel. Maybe this link will help people out. Doug

https://comfortairgr.com/wp-content/uplo........ant-Charge-Information-R134A-Systems.pdf

dougrainer

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Posted: 07/30/21 10:19am Link  |  Quote  |  Print  |  Notify Moderator

If you decide to drain and vacumm the system, just replace both the Hi and Lo side valve core inserts. Do NOT just tighten. They are VERY CHEAP and better to just replace when the system is empty than to just tighten/Charge and then find out they leak from bad seal. Doug

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