Good Sam Club Open Roads Forum: Class A Motorhomes: Dash AC not cold
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buystockinfun

California

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Posted: 08/05/21 04:36pm Link  |  Quote  |  Print  |  Notify Moderator

Are those some kind of special inserts or are they like just something you buy for a tire? In other words did you buy them from an air conditioning place or can just pull one off the shelf of Walmart for example? Thanks

dougrainer

Carrolton, Texas

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Posted: 08/05/21 06:01pm Link  |  Quote  |  Print  |  Notify Moderator

buystockinfun wrote:

Are those some kind of special inserts or are they like just something you buy for a tire? In other words did you buy them from an air conditioning place or can just pull one off the shelf of Walmart for example? Thanks


NOT tire. especially 134a fittings. You can go to most large Auto supply and tell them you what Hi and Lo side 134a valve cores. Doug

dougrainer

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Posted: 08/05/21 06:04pm Link  |  Quote  |  Print  |  Notify Moderator

dodge guy wrote:

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!


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


That is exactly from the Manufacturer of the Largest Maker of RV dash AC systems and obviously from THEIR Engineers in their manual. I also know how to read gauges (42 years of experiance). Doug

hughesjm21

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Posted: 08/06/21 09:30pm Link  |  Quote  |  Print  |  Notify Moderator

On one of my coaches I had similar pressure indications. I found out the dryer had an oulet screen that failed and allowed resin like beads to flow downstream to restrict flow through the expansion valve. After replacing dryer and expansion valve cooling returned to normal.

buystockinfun

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Posted: 08/06/21 09:48pm Link  |  Quote  |  Print  |  Notify Moderator

I'm going to take a guess that you're right about the dryer and the beads into the expansion valve. I wonder if I'll replace that myself and then have an AC guy fill it I don't know that I'm qualified to fill the air conditioner myself but then again I don't know that I'm qualified to determine if it's the dryer or not either. Where I live it's very hard to find a good AC guy

JRscooby

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Posted: 08/07/21 04:33am Link  |  Quote  |  Print  |  Notify Moderator

I don't know a lot about AC systems, but if you are getting over 20* drop (85* outside, but you have not posted the temp of air at intake) I would look at side of engine where heater hoses connect. Most times there are valves to shut off flow of coolant thru heater. Much better than putting a weak spot in hose with vice grips

Rick Jay

Greater Springfield area, MA

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Posted: 08/07/21 11:07am Link  |  Quote  |  Print  |  Notify Moderator

JRscooby,

I agree, and this was mentioned in the first page of posts. It would be relatively easy to add a manual shut-off valve on the inlet hose of the heater core, if there's not one already installed. It doesn't take much hot coolant leakage to overpower the cooling ability of the A/C. Buystockinfun, if there is already a manual valve installed, try shutting it off to see if that helps.

Though, that wouldn't account for your low pressure readings being on the low side.

Good Luck,

~Rick


2005 Georgie Boy Cruise Master 3625 DS on a Workhorse W-22
Rick, Gail, 1 girl (24-Angel since 2008), 1 girl (20), 2 boys (21 & 18).
2001 Honda Odyssey, Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.


buystockinfun

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Posted: 08/07/21 11:41am Link  |  Quote  |  Print  |  Notify Moderator

Yeah I think the shut off maybe makes it more efficient so I'm not opposed to doing that. I don't know that it helps cooling the motor very much considering the size of the engine and how small that area is under the dash but I think on other cars like small cars or even trucks that can help cool the motor sometimes you're having an overheating problem you can run the heater I think I've done that before. But you're right about the low pressure thing and I think that's actually the major indicator. I have a feeling something's broke loose maybe with that dryer or something and it's plugged up the system in some way. That being said I'm told that 20° from ambient Air temperature is a great drop somebody said something about intake air temperature well let's just say that that is the same as the outside air temperature even though it hasn't been tested once you get some cooling in the cab at your feet let's just assume the temperature is the same I haven't read it but it probably is very close cuz it's blowing out and then you have the whole camper and until you're running the air conditioner in the camper it's probably some pretty warm air going into the intake vents I assume on the floor I don't really know if that's a heating vent or where it intakes exactly but assuming it's on the floor somewhere that's probably at least the same temperature as it is outside. It does cool a little better when the camper temperature is lower running the generator cooling the entire camper. Then you get a cooler sort of feel but a lot of that is because the entire camper is cooler anyway.

But if you're supposed to be getting readings like the RV guy said of 35° I just don't believe that I think coming out of that thing during the summer you'll be lucky to see 45° maybe 52 anywhere in the USA down on the lower 48 anyway I don't see 35 I mean unless you're running the air conditioner in the winter Maybe... Maybe 20° drop is the answer if it's 85 outside and it's blowing out at 65 I should be happy but it sounds like it should be cooler than that and I think it should be coming out in the 50s anyway and so therefore that kind of indicates a problem in my opinion.

I am going to probably do the diverters to block that the only have to do it one way like one valve to stop it from flowing in or do you have to put it on both sides? Also any comments about the above with the air temperature thing am I misunderstanding that I mean if it's 20° I should be good then there's absolutely nothing wrong but then why the pressure problem I think solve the pressure problem by whatever is causing that and I get better temperature out of the dash.

JRscooby

Indepmo

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Posted: 08/07/21 04:06pm Link  |  Quote  |  Print  |  Notify Moderator

Rick Jay wrote:

JRscooby,

I agree, and this was mentioned in the first page of posts. It would be relatively easy to add a manual shut-off valve on the inlet hose of the heater core, if there's not one already installed. It doesn't take much hot coolant leakage to overpower the cooling ability of the A/C. Buystockinfun, if there is already a manual valve installed, try shutting it off to see if that helps.

Though, that wouldn't account for your low pressure readings being on the low side.

Good Luck,

~Rick


If valves was mentioned, and I missed it, I'm sorry. I did see something about vice grips on hose. That could (likely would) cause damage to hose. Do it to somebodies rig, then charge to later fix leaky the hose is a questionable deal to me.

OP I mentioned the intake temp, and the amount of drop you are getting.
Back in my youth I took the AC out of a pickup, put in my 427 GMC. Now that truck had 2 gearboxes under a not well insulated floor, lots of other ways heat could get in. And because of the loads we carried, we would shim the back edge of hood up to let some heat from under hood. Worked on it for hours, on a 90* day, air at vent was about 75* Gave up when I taped the thermometer to the cowl in front of windshield where could read going down the road. The air it was picking up was over 140*

down home

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Posted: 08/07/21 10:04pm Link  |  Quote  |  Print  |  Notify Moderator

Our Revolution had o rings in line replaced and filled with refrigerant several times. Finally it wasn't putting out any cool air in Kingman,AZ last year, again. The evaporator under the coach, is part of the chassis, was corroded etc. Found the only one available, or in existence apparently in Main, I think, and may have replaced the fan too. Freedom Roads in the Northeast was first Dealer, and it was apparently exposed to salt etc. I did get underneath and rinse it really good a few times, over, the 19 years we owned it.
Freightliner Service Center in Kingman got it fixed proper. Long hoses from the ac compressor forward.
Generally if they leak you will may see compressor lube and or dye leaking from the o-rings or holes or stains.
Once we got 100 miles east of Kingman we cut the generator and heat pumps off, Seldom had to use them the rest of way home. It blew cold. We many/most of the times kept the a/c set on max to recirculate inside air as there is no filters on the dash air intake, something I never got around to deigning and making. On a long trip with outside dash air everything seemed to get coated with dust.

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