Dash AC not cold

[buystockinfun]

I'm wondering if my expectations for my Dash AC are set too high. It just doesn't seem to blow very cold. When it is about 85 out it comes out about 63 out of the dash with an AC temperature gauge. I tried it on a rental car and it was coming out like 50 degrees at the same time for the rental. Never had any luck doing AC pressure readings but I did buy a gauge set. I hear if it has an expansion valve you can't get quite the right readings but then I also read that if the pressure isn't changing on the low side then you have something stuck or plugged and I'm not sure what that is.

At 85° I get a pressure of about 255 on the high side which appears from when I'm reading to be accurate but the low side is just 15. No matter how much Freon I put in there the low side pressure doesn't change and the high side pressure goes up and of course I have to evacuate that because it can't be too high I don't want to ruin the compressor. Also not sure what type of oil to put in I believe it's some kind of 46 oil but there's no real accurate information to confirm that there's a bunch of different oils. The compressor appears to be engaged fine. I did notice when I put fluid in you could see a little tiny bubbling from the high and low sides I tighten the needle valve down. This could indicate some kind of bad o-ring or needle valve that needs replaced I did put a new needle valve in one of them but I think it still has a little bubble where the needle valve is I think it also goes away though I guess when it gets agitated or something maybe they can bubble out a little I'm not sure. But this could indicate a separate problem I think regardless of the needle valve when you put 5 lb in there the pressure still on the left side never goes up above 15. So like I say two different advice that I saw on forums were that something is sticking cuz it should go up between 30 and 50 psi but then a contradictory for him said that because it might have an expansion fitting that it never will fluctuate or something but it just seems too low for me.

I can't find an AC place that will even look at it because it took camper and a diesel pusher. Maybe 63°is a normal reading with the compressor way in the back. But I really have no information on the routing or any of this for this it would be great to get a diagram of how it's routed and how many pounds it would take I mean I'm guessing it's about four to five pounds somebody said on some forum somewhere. It is r134a system.

This is a 2006 Monaco executive with a 525 horsepower isx15 Cummins engine that was supposedly upgraded to 600 HP on a Roadmaster
chassis.

Sorry for the long post but at least it's a full explanation hopefully. Not sure how to add pictures I don't see that option maybe I'm too new. Oh and most forms people don't post their solutions which drives me crazy so I promise I'll post a solution if I find one or what the final analysis was for example on the low pressure.

[buystockinfun]

Well I'm in a standstill till I get home so I will update everyone when I can get professional eyes on this or dig into it a little more where I'm not on the side of the road..

[Rick_Jay]

buystockinfun,

I'm sorry to hear of your A/C woes, hopefully things will be fine soon.

I do have to say, though, as I read through this thread, that there are parts of your posts which suggest that you know "just enough to be dangerous", as they say. LOL A/C is not difficult work, but it IS precise work. And you can cause some expensive damage to components if procedures aren't followed properly. Proper equipment, gauge set, accurate thermometers and if possible, having the pressure/temperature/humidity charts for the system you're working on, make it easier to properly diagnose the system. As has been pointed out, too much refrigerant decreases system efficiency, so it's a very delicate balance.

I believe you mentioned several times about "draining" the system. It's very important that the system be evacuated in a controlled manner. Not just "drained" as the term implies. If you just open a schrader valve and let the refrigerant out, it'll take a lot of the system oil with it. The proper oil charge in the system is very important as well. Each component that is removed will remove some of the oil with it. That oil should be measured upon removal, and an equal amount installed upon assembly. If you're going to flush the entire system anyway, then it doesn't matter much as you'll be starting from fresh with the oil charge.

IF you think the system is overfilled now, I'd put some gauges on it, try to find the proper charts for your system and see how it performs based on the charts. Check the air temp leaving the vents in the moho. While releasing R-134 into the atmosphere is prohibited by law, IF you can figure out a way to slowly release some of the refrigerant, then you can stop and watch the temp in the vents. If it goes down (colder), you probably do have too much refrigerant in the system. If it goes up, you might not have enough. If it stays the same, try releasing a bit more. Of course could have other problems. But seeing as it might be overcharged, the cheapest and easiest route at this point is to slowly reduce the charge while watching the effect on outlet temps. This will take a while as you need to give some time for the system to stabilize. Even before you start doing anything, you have to let the system run for a while to stabilize the temperature of the ducting/vents etc.

If all else fails with no improvement, then you'll be where you're headed now. Opening the system, replacing some common components, flushing the system, adding oil and recharging. Again, keep everything clean. Once the system has been flushed and reassembled, pull a vacuum on the system and let it stay for a couple of hours to make sure there are no leaks.

Good Luck, I hope you find the source of your problem.

~Rick

[wa8yxm]

When it is 85 it comes out 63... Normal operation for the new refrigerante systems (what is that R-134A) the older Freon (R-12) systems got colder

[buystockinfun]

I'll have to have somebody troubleshoot it probably going to need a new dryer and I guess I'm just going to guess an expansion valve if it has one and then completely flushed and then refilled. I suppose there's a chance that it's either too high or too low on refrigerant but without draining it doing any kind of cleaning that needs to be done however y'all do that and then refilling it. Not going to do all that without testing it in terms of the dryer and stuff first. I assume that's what's a professional would do anyway. Temperatures only getting to about 62° most of the time maybe a little lower on the cooler day and the low side doesn't change at all which doesn't seem from everything I'm hearing to be correct. So probably something wrong. The guy that told me he seen him take 10 lb also said that the dryer if it was going bad would be all froze up and I haven't seen that I haven't seen anything on that dryer at all in terms of moisture.

But if everything was good but levels. Wouldn't we see the low side increase or decrease in pressure?

[ernie1]

I concur with Dodgeguy's reply. That's the way I was taught by my refrigeration instructor who was also a mechanical engineer.

[dodge_guy]

dougrainer wrote:

dodge guy wrote:
Sounds like it’s low on refrigerant. You would need gauges to accurately see the pressures and determine how much it needs.

From the EXPERTS on the link I posted. Gauges are good but you CANNOT accurately determine the correct charge. As I stated, TOO MUCH coolant will cause low output as well as LOW coolant. Gauges cannot be that accurate to determine that. You can get close but close will not give you the BEST cooling other than an exact charge. If I was paying somebody, I want the BEST not close. Doug

From the link.

the only way to be certain of an exact charge is to fill an empty system with the
specified amount of R-134a refrigerant.

A good AC guy knows how to read gauges (and I am one of those people). You have to know outside temp and humidity and have a chart to compare that to the pressures on your gauges as well as the vent outlet temperature. It can be done with the right person. Sadly not many like that left anymore!

[dougrainer]

Last, When you had Freon 12 you could use the sight glass of the Dryer and when the bubbles quit you were pretty darn close to the correct charge. With 134a, you will always have Bubbles with the correct charge. Doug

[dougrainer]

dodge guy wrote:
Sounds like it’s low on refrigerant. You would need gauges to accurately see the pressures and determine how much it needs.

From the EXPERTS on the link I posted. Gauges are good but you CANNOT accurately determine the correct charge. As I stated, TOO MUCH coolant will cause low output as well as LOW coolant. Gauges cannot be that accurate to determine that. You can get close but close will not give you the BEST cooling other than an exact charge. If I was paying somebody, I want the BEST not close. Doug

From the link.

the only way to be certain of an exact charge is to fill an empty system with the
specified amount of R-134a refrigerant.

[dodge_guy]

Sounds like it’s low on refrigerant. You would need gauges to accurately see the pressures and determine how much it needs.

[RLS7201]

dougrainer wrote:

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/uploads/2020/02/eti-Refrigerant-Charge-Information-R134A-Systems...

Doug make a point about the compressor failing but there are other reasons for the screen to get choked. I.E acid in the system and the desiccant sack in the dryer ripped and allowing desiccant into the system. No matter, always change the receiver/dryer.

Richard

[dougrainer]

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

[dougrainer]

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/uploads/2020/02/eti-Refrigerant-Charge-Information-R134A-Systems...

[buystockinfun]

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.

[buystockinfun]

[buystockinfun]

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.