AC Issues and Duracool (HC12a)

[traveler1980]

Hi All. I posted this on GMCNet and here to get as much input as possible.

The dash AC system in my rig was converted to R134 sometime in the past 5 years or so. The PO then replaced the R134 with Duracool (HC-12a). My AC still blows nice and cold, but there is a leak right under the front hatch on the high side where there's a T feeding refrigerant to two evaporators - the stock one and an auxiliary unit installed under the dash in the coach. I can see bubbles coming from the connection and there is oil on the lines. I've had no luck getting anyone to work on a Duracool system. I guess they're worried about liability. Do I need to buy an evacuator, tank, and vacuum pump and repair this myself? For those that use Duracool, do most of you work on your own systems?

I have no AC experience, but I guess there's no time like now to learn something new.


Update - The guys on the GMCNet forum suggested that I just let the system leak down and then I can depressurize whatever Duracool remains, fix the leak, and then take it to a shop to have the system vacuumed. Sounds reasonable to me so long as I don't damage the compressor in the process. I know it will shut down when the pressure gets too low.

 

[JSanford]

I do my own work, but I have several old cars so I have the vacuum pump and gauge set on hand. Not sure what a evacuator tank is, they make big expensive refrigerant recycling machines but that is for real refrigerants like R12 and R134a not Dura Cool. AutoZone has a tool loan program, they might have the gauges and vacuum pump. Just let the Dura Cool out, replace the bad component and then vacuum it down and refill.

 

[traveler1980]

I do my own work, but I have several old cars so I have the vacuum pump and gauge set on hand. Not sure what a evacuator tank is, they make big expensive refrigerant recycling machines but that is for real refrigerants like R12 and R134a not Dura Cool. AutoZone has a tool loan program, they might have the gauges and vacuum pump. Just let the Dura Cool out, replace the bad component and then vacuum it down and refill.

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Thanks @JSanford! I think the term I was looking for was “refrigerant recovery machine,” not “evacuator.” They are super expensive and I would definitely prefer not to have to purchase one. When you say, “let the Duracool out,” how do you do that? Do you just vent it from the low pressure port? Will that also remove it from the high pressure side or would I also have to somehow drain/vent the liquid from that side?

 

[JSanford]

Thanks @JSanford! I think the term I was looking for was “refrigerant recovery machine,” not “evacuator.” They are super expensive and I would definitely prefer not to have to purchase one. When you say, “let the Duracool out,” how do you do that? Do you just vent it from the low pressure port? Will that also remove it from the high pressure side or would I also have to somehow drain/vent the liquid from that side?

You only use the low pressure port, don't even touch the high side. Just hook up the gauge set without the vacuum pump attached and open the valve and the Dura Cool will go away.

 

[tmsnyder]

The amount of Duracool in there is literally less than a pound of a propane / butane blend. It doesn't need to be recovered.

To put it in perspective, if you've ever had your propane tank filled on your GMC, they open a small vent valve to allow propane vapor to vent while they pump in liquid propane. I'm sure this is more than a pound.

The leak could be at an o-ring or maybe where they swaged on the fittings. Good luck with the fix.

 

[traveler1980]

Thanks for the help, guys!

 

[bdub]

You don't even need a gauge set. Just get the single low side gauge sold at most auto parts stores. Vacuum down for a few hours to make sure it holds. It only takes less than 2 cans of propane coolant, and there are several besides Duracool. Set low side on about 20# with engine running ~1500rpm and the AC fan on high coolest it'll go. If you get too much in there, just bleed some off. It'll get cold, then if you add too much, it'll warm up some. Best to go just a little over to keep it from freezing up.

 

[traveler1980]

You don't even need a gauge set. Just get the single low side gauge sold at most auto parts stores. Vacuum down for a few hours to make sure it holds. It only takes less than 2 cans of propane coolant, and there are several besides Duracool. Set low side on about 20# with engine running ~1500rpm and the AC fan on high coolest it'll go. If you get too much in there, just bleed some off. It'll get cold, then if you add too much, it'll warm up some. Best to go just a little over to keep it from freezing up.

Thanks for the advice, @bdub. Having never worked on AC, it’s a little intimidating, but it sound a lot simpler than it looks based on what everyone is saying.