How to recharge your AC?

[huntindog]

[QUOTE=BigSwick;334755]

I see now that I don't have the necessary equipment or knowledge to attempt this. I was thinking it was like recharging a car, but with different refrigerant. But you can buy the r410a on ebay: https://www.ebay.com/itm/203012297431

As an additional FYI, the same principle applys to a car.... Of course it you are using one of the recharge kits that are available everywhere now, then they have idiot proofed it.... But those kits have their issues as well. Those that know ACs call them death kits, as they kill your AC system by adding other ingredients than refrigerant.... This causes long term damage nessitating a complete replacement of the system. BIG $$$$$$$
Proper AC charging requires manifold gauges and the knowledge to use them properly AND safely

[Steven@147]

[QUOTE=huntindog;334793]

As an additional FYI, the same principle applys to a car.... Of course it you are using one of the recharge kits that are available everywhere now, then they have idiot proofed it.... But those kits have their issues as well. Those that know ACs call them death kits, as they kill your AC system by adding other ingredients than refrigerant.... This causes long term damage nessitating a complete replacement of the system. BIG $$$$$$$
Proper AC charging requires manifold gauges and the knowledge to use them properly AND safely

Absolutely. I have installed numerous aftermarket AC systems in hot rods from Classic Auto Air and Vintage Air. And always, always pulled a vacuum and charged from the low pressure side of the system.
The kits you can get at autoparts stores or cans of 134 most likely have a sealer in them that will destroy a modern AC system and plug it completely. Then you have no recourse but to go through and replace all the components, very expensive. And yes those kits will only connect to the low pressure side of the system because the low and high pressure connections are different sizes.
It has gotten so bad that most auto repair shops will not touch an AC system that has been "monkeyed" with (their words). Some will not touch an aftermarket AC system. Several shops had their AC charging stations plugged up by people using those store bought kits using sealers in the can. When I had my shop I i worked on a lot of R12 systems. Converted a lot of R12 to R134. Now you would have to have a separate system for R1234yf.

Unfortunately in the RV world the AC units are pretty much disposable if problems are with the compressors, condensers, leaks in the system, even pressure switches, you have no recourse but to replace the complete unit. About the only thing you would be able to do is replace the fan motor or electronics.

[sgrol60]

[QUOTE=huntindog;334734]

DANGER
Do not attempt this
You can get hurt or blinded
Doing this on the high side of a running ac will over pressure the Freon canister and probably explode it
Charging on a running ac can only be done on the low side
If you do not understand ac do not attempt this or give advice on forums
It is a dangerous procedure

You are dead on and anyone attempting to charge on the high side could just end up dead. I have installed the saddles and charged many rooftop a/c units that were R22 which operates at much lower pressures.

[BigSwick]

Thanks to advice from you fellow campers, I did not attempt to recharge the AC. Dometic sent out a new AC one under warranty. After six weeks or more, it finally arrived. The local mobile techs arrived this morning to install. They opened the box, and it looked like somebody literally dropped it off the truck. The plastic shroud was broken and the base looked to be bent. The tech called Dometic and they said to throw it away and they are sending out another new one. Hopefully it won't take another 6 weeks. pretty disappointing. But the new (broken) one did say "evolution" on the cover. Whatever that means.

[BigSwick]

The new AC finally came in and got installed 3/10/21. So about 3 months from time it was first ordered with Dometic until a usable unit was delivered and installed. Good thing is that I now have a new 2 year warranty on it. So if you need a new unit, plan on a delay in getting it.

[Dawgfever]

Good info gentlemen. My rear AC is not putting out cold air...called mobile RV guy and he said what all you are saying. Can't be recharged / buy a new one. Geez and just a year out of warranty. So its time to hit the forum...

So do I go with Dometic (orginal) or do I go with another brand, preferably a quite one. What say you O Wheeled Travelers Who Reside in Boxes?

Ed

[sgrol60]

Good info gentlemen. My rear AC is not putting out cold air...called mobile RV guy and he said what all you are saying. Can't be recharged / buy a new one. Geez and just a year out of warranty. So its time to hit the forum...

So do I go with Dometic (orginal) or do I go with another brand, preferably a quite one. What say you O Wheeled Travelers Who Reside in Boxes?

Ed

That is just not true. They can easily be recharged. The question is - Is it leaking somewhere and if so can it be repaired (re soldered). While it may not be the right decision financially to fix them, they can (usually) be fixed. I repaired many roof top units when I worked in Mexico and had no other choice (and freon was dirt cheap).

[my12by60]

That is just not true. They can easily be recharged. The question is - Is it leaking somewhere and if so can it be repaired (re soldered). While it may not be the right decision financially to fix them, they can (usually) be fixed. I repaired many roof top units when I worked in Mexico and had no other choice (and freon was dirt cheap).

I have been reading this thread with interest. We have a used 2017 29RS that we just took for a one week shake-down trip. The unit has a 15K Dometic on the rear and a 13.5K Dometic on the front. The rear AC blows nice and cold. The front AC is only slightly colder than ambient.

We have the PD EMS which shows me the amp draw on each of the Line 1 and Line 2 AC power feeds. With all else off, I confirmed an 11 amp draw from the front AC when it is running. So that confirms that the compressor is running and also makes it highly likely that the AC has lost refrigerant, which is r410a according to the label under the shroud. I removed the shroud and looked for any signs of a leak, but saw nothing other than a unit that looks brand new.

Before I simply scrap the unit, I am inclined to try the saddle valve and then recharge with a bit of sealant followed by r410a.

Here is why:

My 4-ton home AC lost its refrigerant about 7 years ago. I had a tech come out and add a can of Easy Seal followed by refrigerant. The unit has worked fine and not required any additional service since then. In researching Easy Seal, I found many horror stories on the internet about how adding any sealant would ruin the system, how sealant was snake oil, how sealant was only for hacks, etc. Maybe I just got lucky with my experience.

Anyway, since so many say to just scrap the Dometic, I don't see any harm in trying the saddle valve, sealant, refrigerant route.

sgrol60 - Since you have experience with this, I have a few questions for you on how to do this for the best chance of success:

What is the best piece of tubing to attach the valve to? I know I need the low-pressure side. The compressor has tubing that exits toward the front of the coach and enters cooling fin area and tubing that returns from the cooling fin area and re-enters the compressor. Is the low side the return side, which is toward the rear of the unit? Will any straight run of tubing work or do you have a preferred location for the valve?

Have you used sealant in the repairs you did? If yes, what brand do you prefer and how much did you add?

My plan was to just add refrigerant in small dabs while my wife was inside reporting on how cold the air was getting while monitoring a stick thermometer placed in one of the vents. Once we get to a 15 to 20 degree spilt vs. ambient temps, we would stop adding refrigerant.

Do I need a special fitting to add the r410a? I have the saddle valve in hand. I ordered this one: https://smile.amazon.com/dp/B00DM8J3...t_details&th=1

My cheap auto AC fill hose does not fit the fitting on the saddle valve as the male valve on the saddle is smaller than the female fitting on the hose. Can I just buy a can of like this:

https://www.ebay.com/itm/20368065294...3ABFBM9Pmak5xf

If yes, then it looks like I would net an adapter to go from the male fitting on the 410a to the male fitting on the saddle valve. Is such an adapter available?

Any other tips or advice would be appreciated. Thanks.

[Crazybanshee]

Huntindog you are correct. I have been doing AC work for 30 years and never tried to charge to the high side. It is not for an amateur to try.

[sgrol60]

I have been reading this thread with interest. We have a used 2017 29RS that we just took for a one week shake-down trip. The unit has a 15K Dometic on the rear and a 13.5K Dometic on the front. The rear AC blows nice and cold. The front AC is only slightly colder than ambient.

We have the PD EMS which shows me the amp draw on each of the Line 1 and Line 2 AC power feeds. With all else off, I confirmed an 11 amp draw from the front AC when it is running. So that confirms that the compressor is running and also makes it highly likely that the AC has lost refrigerant, which is r410a according to the label under the shroud. I removed the shroud and looked for any signs of a leak, but saw nothing other than a unit that looks brand new.

Before I simply scrap the unit, I am inclined to try the saddle valve and then recharge with a bit of sealant followed by r410a.

Here is why:

My 4-ton home AC lost its refrigerant about 7 years ago. I had a tech come out and add a can of Easy Seal followed by refrigerant. The unit has worked fine and not required any additional service since then. In researching Easy Seal, I found many horror stories on the internet about how adding any sealant would ruin the system, how sealant was snake oil, how sealant was only for hacks, etc. Maybe I just got lucky with my experience.

Anyway, since so many say to just scrap the Dometic, I don't see any harm in trying the saddle valve, sealant, refrigerant route.

sgrol60 - Since you have experience with this, I have a few questions for you on how to do this for the best chance of success:

What is the best piece of tubing to attach the valve to? I know I need the low-pressure side. The compressor has tubing that exits toward the front of the coach and enters cooling fin area and tubing that returns from the cooling fin area and re-enters the compressor. Is the low side the return side, which is toward the rear of the unit? Will any straight run of tubing work or do you have a preferred location for the valve?

Have you used sealant in the repairs you did? If yes, what brand do you prefer and how much did you add?

My plan was to just add refrigerant in small dabs while my wife was inside reporting on how cold the air was getting while monitoring a stick thermometer placed in one of the vents. Once we get to a 15 to 20 degree spilt vs. ambient temps, we would stop adding refrigerant.

Do I need a special fitting to add the r410a? I have the saddle valve in hand.
My cheap auto AC fill hose does not fit the fitting on the saddle valve as the male valve on the saddle is smaller than the female fitting on the hose. Can I just buy a can of like this:

If yes, then it looks like I would net an adapter to go from the male fitting on the 410a to the male fitting on the saddle valve. Is such an adapter available?

Any other tips or advice would be appreciated. Thanks.

This is what I have used on several systems and have had good luck with it:

https://www.amazon.com/Cliplight-Sup...U%2CB00BYS6SV2

Charging a system will involve a gauge set (and vacuum pump if all freon has been lost). You need to charge up until the low side pressure reads higher than 108 PSI F (which corresponds to an evaporator temp of 35 deg F on a 410a system) so the evaporator coils don't freeze up. The saddle valve you ordered should work fine as long as it snugly fits the line it is installed on. The inside coil is your evaporator and the line from it to the compressor is the low pressure side. Any lines going to the cooling fins on the outside (top of RV and exposed to the ambient outside air) are high pressure and you need to stay away from them. I would go in this order:
1. attach saddle valve to a straight and perfectly round low pressure copper line
2. attach blue hose or low pressure side of gauges to the saddle valve and then open the valve to allow a pressure reading on the gauge.
3. turn on the a/c and watch the gauge. If it starts dropping in pressure you are on the low side, if it rises in pressure you are on the high and wrong side
4. bleed the blue hose at the gauge connection by cracking it open to let a little freon (and air) out then close the hose connection
5. After you confirm you are on the low side, you can start to add refrigerant until the 108 PSI is reached ( should be warm outside and inside, don't want to do this when it is cold or below, say, 65 deg) (again, when you hook up to the freon can bleed the air out at the gauge connection before you introduce freon into the system)
6. After the system is charged up properly you can add the leak stop by following the directions on the can.

Good luck and be careful. You can blow up a freon can into your face if you hook it up on the high pressure side of the unit.