Dash ac recharge on class a diesel pusher

[GTMADNS]

Just turned dash ac on this past weekend. It blows cool but not cold like it used to. Is it easy to charge yourself? This is a 2006 coachman cross country. Let me know your thoughts. Thanks

[mike_brez]

dougrainer wrote:

Ivylog wrote:

crasster wrote:
Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

Really, How is air going to get into a system that is still cooling, but not as cold as normal... is still pressurized and has enough freon in the system to work somewhat? Even while working the low pressure side will have 60+ psi in it... how is air going to get in???

Bingo. HOW can air get into a pressurized system? IF the system has been open to the atmosphere, then yes, find the leak, then Vacuum and charge. Vacuum can also let you know if the system has a large leak. Small leaks that happen under pressure, a Vacuum test rarely is accurate. Now, HOW is a novice supposed to know how much 134a to install? Unless you have your gauges connected and do a digital temp at closest outlet to the evaporator, you will have a hard time getting it filled correctly. BTW, SMALL leaks will not cause Oil loss. TOO MUCH 134a is as bad as too little. Too much and the system will not cool correctly just like too little. A TEST for posters. HOW much 134a(lbs) do you think a average Diesel RV motorhome takes? Doug

A diesel pusher about 3-4 lbs

[rgatijnet1]

dougrainer wrote:

Ivylog wrote:

crasster wrote:
Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

Really, How is air going to get into a system that is still cooling, but not as cold as normal... is still pressurized and has enough freon in the system to work somewhat? Even while working the low pressure side will have 60+ psi in it... how is air going to get in???

Bingo. HOW can air get into a pressurized system? IF the system has been open to the atmosphere, then yes, find the leak, then Vacuum and charge. Vacuum can also let you know if the system has a large leak. Small leaks that happen under pressure, a Vacuum test rarely is accurate. Now, HOW is a novice supposed to know how much 134a to install? Unless you have your gauges connected and do a digital temp at closest outlet to the evaporator, you will have a hard time getting it filled correctly. BTW, SMALL leaks will not cause Oil loss. TOO MUCH 134a is as bad as too little. Too much and the system will not cool correctly just like too little. A TEST for posters. HOW much 134a(lbs) do you think a average Diesel RV motorhome takes? Doug

If the system is still pressurized then who cares how much freon the system holds? All you really need is a thermometer. Placed in the outlet of one of the ducts, add freon slowly until the temperature drops to it's lowest and starts to go back up. As soon as that happens, you stop. You are right, too much is as bad as not enough so you add for the lowest temp reading.
Now this is not scientific and is not how a tech would do it but for a NOVICE, it will work just fine and probably save them a lot of money.

[dougrainer]

Ivylog wrote:

crasster wrote:
Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

Really, How is air going to get into a system that is still cooling, but not as cold as normal... is still pressurized and has enough freon in the system to work somewhat? Even while working the low pressure side will have 60+ psi in it... how is air going to get in???

Bingo. HOW can air get into a pressurized system? IF the system has been open to the atmosphere, then yes, find the leak, then Vacuum and charge. Vacuum can also let you know if the system has a large leak. Small leaks that happen under pressure, a Vacuum test rarely is accurate. Now, HOW is a novice supposed to know how much 134a to install? Unless you have your gauges connected and do a digital temp at closest outlet to the evaporator, you will have a hard time getting it filled correctly. BTW, SMALL leaks will not cause Oil loss. TOO MUCH 134a is as bad as too little. Too much and the system will not cool correctly just like too little. A TEST for posters. HOW much 134a(lbs) do you think a average Diesel RV motorhome takes? Doug

[GTMADNS]

Guys I work at a car dealership we see cars every summer 3-5 years old that blow cool not cold. The Freon over time soaks into the rubber hoses or yes seals start to leak and a recharge will last another 1-3 years. If I have to to recharge 1 time a year I'm fine with it. Wondered how hard it is to do it. The radiator/condenser is easy to see and clean which I do every year. Just did not want to bring Rv to the store or have to bring a machine home vs a can and a recharge hose kit. I will look at it this weekend when kids can give me some time to inspect

[Ivylog]

crasster wrote:
Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

Really, How is air going to get into a system that is still cooling, but not as cold as normal... is still pressurized and has enough freon in the system to work somewhat? Even while working the low pressure side will have 60+ psi in it... how is air going to get in???

[crasster]

Really - while you can DIY recharge, it is BEST if you can put the system under a deep vacuum then charge. It's the proper way to get all the air out so there is more pure 134a.

[rgatijnet1]

Ivylog wrote:

garyemunson wrote:
Something else that can fail on some coach A/Cs is the heater water valve. If it begins to get sticky, it will not fully shut off and will preheat the incoming air to where the A/C cannot get it fully cold. Lots of things to check.

X2. You can buy a 134 freon recharge kit with a gauge...$20. Put it on and you can see if it needs more freon which is likely since it is still cooling. One can will be enough to recharge it almost into the red (to much) which could last for a couple years even with a slow leak. The system will cool well over a fairly wide pressure range.

That is correct. I'm going to assume that this is the first time that you have had to add freon to a 10+ year old coach. It may be just a very slow leak and the addition of a can or two of freon may last you another 10 years. On the other side, yes an AC tech MAY be able to find the leak, at $100/hour as he traces your freon lines from front to back. Personally, I'd go the cheap route first.

[Ivylog]

garyemunson wrote:
Something else that can fail on some coach A/Cs is the heater water valve. If it begins to get sticky, it will not fully shut off and will preheat the incoming air to where the A/C cannot get it fully cold. Lots of things to check.

X2. You can buy a 134 freon recharge kit with a gauge...$20. Put it on and you can see if it needs more freon which is likely since it is still cooling. One can will be enough to recharge it almost into the red (to much) which could last for a couple years even with a slow leak. The system will cool well over a fairly wide pressure range.

[garyemunson]

Something else that can fail on some coach A/Cs is the heater water valve. If it begins to get sticky, it will not fully shut off and will preheat the incoming air to where the A/C cannot get it fully cold. Lots of things to check.

[Ski_Pro_3]

Other things that might cause the air vents to only blow cool, not cold;
The condenser or the evaporator are blocked or partly blocked.
The condenser is usually located where the radiator is. But instead of bleeding off heat with water, like radiator, it bleeds off heat with compressed freon.
The evaporator is located inside the dash. The compressed liquid freon is routed though a valve, much like a spray water hose nozzle, where the liquid is converted to gas due to the loss of pressure, just like a garden hose with a mister; high pressure on one side/ low pressure on the other and you get a chilling mist.
If either of these; condenser or evaporator, are clogged with dirt, dust, bugs, mouse nest(mine was over a winter storage once) then the transfer of heat/cold isn't as great as it could be.

[Ski_Pro_3]

The only reason a charge would work is if there's a leak. If there's a leak, charging is a very temporary fix and not cheap. For around $100, a good AC tech will pinpoint the cause of the diminished cooling, which might not be due to low freon.
Speaking of which;
If your AC is only cool, not cold like it used to be, it's most likely not due to a leak of freon. Here's why; there is a pressure switch that will operate the compressor so that the compressor will not operate if there isn't enough freon in the system. As freon is lost, at first the AC will blow colder air than it would with a correct amount of freon. The reason for this is that freon is converted from a liquid to a gas to chill. When fully charged, the freon doesn't fully convert to gas, there's too much of it. When freon leaks, it approaches a magic point where 100 percent of the freon evaporates to a gas. At this point the AC will blow it's coldest. However, if freon continues to leak, the pressure switch will kick in and there will be no chilling to the air. The reason the pressure switch kicks in is so that the compressor is protected. You see, freon contains oil that lubricates the compressor. When you leak freon, you also leak the lubricating oil.

In a nutshell, an AC unit will fail in this order if there's a freon leak;
1. normal chilling from vents
2. increased chilling from vents
3. no chilling from vents and compressor clutch won't engage because the pressure switch senses the loss of freon and subsequent lubricating oil

[lj2654]

it may have a leak.....I spent $1800 replacing my whole system and having it charged. It lasted for a week then not cold again. took it back to CAT service and they wanted to look for another hose leak at $139 an hour, I left!

[MountainAir05]

it is if you have a gauge or a loaner from one of the auto parts stores. Really helps if you know something about charging an AC the proper way.