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Using Propane in Volvo AC

In moderate climates r-134a seems quite fine but in hot climates a large r-134a or much better r-12 are the only thing that works. I am talking 110+F and humidity with a parked car with a interior temperature of 160+F. Typical summer day here or worse.

Hydrocarbons are the best in just about every way, they are getting a lot of attention in the past few years. There is a flammability issue and understandable although exploding throwing bodies around is a bit much.

Systems use it now and hopefully more so in automobiles to come. Just keep everything under the hood and run coolant lines in the cabin and then safe as gas. Dupont makes a fortune and all the certified equipment and techs are a big force to keep Freon, not safety concerns.
 
Barton said:
How is this done? There are no external adjustments that I can see.
Dave
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First you should verify that it is freezing up and we are at the point to adjust it. Can you tell if the Evap has ice on it and/or air flow is slowing down.

What dose the valve look like assuming it is an expansion valve?
 
25psi said:
Just looking a little bit at Duracool's( HC blend) comparison chart (which is part propane) has you putting in ~1lbs of their blend if the system was spec'd to hold 2.5-3lbs of R12. Not exactly comparable because their blend contains other chemicals.
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If it's an HC product, then it's comparable.

Looking at the Duracool 12a MSDS at http://www.duracool.com/msds/webmsdscylr.pdf reveals this:
Methylethylmethane 15-40% (the common name is Butane)
2-methylpropane 30-60% (known as Isobutane)
dimethymethane 40-70% (made from methanol and primarily used as a solvent and in the manufacture of perfumes, resins, adhesives, paint strippers and protective coatings)

Maybe pure propane is just too damned strong and a blend of some kind is the way to go.

25psi said:
You might actually want to try a little bit more in the system. If it's warmer out I would get it to ~35-40psi at 1500rpm.
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I began this 'experiment' with about 11 oz and have reduced the charges down to 5 oz. I don't see how going the other direction will help, since it appears less propane is needed to bring evap temps up from the freeze threshhold.
Edit: And since the last 5 oz charge, I've vented the system via shrader valve three times for about 60 seconds each to remove some of the propane. I have no idea how much has been removed, but I'll continue this between freeze-ups until something changes.

Can anyone support an argument for more than 11 oz?
It typically brings pressures up by quite a bit. Low side with this much was 40 to 50 psi (but eventually settled on 30) and high-side was 250.
 
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I've been seriously considering this lately. R134a just isn't good enough for me here in Houston, even with all of the new, updated system parts.

One thing I've been wondering, though: what orifice valve would I use with propane? Will I need to change the R134a variable valve in the system right now, or is it suitable?
 
moxy123 said:
First you should verify that it is freezing up and we are at the point to adjust it. Can you tell if the Evap has ice on it and/or air flow is slowing down.
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Can't see the evap, but air flow never changed. Plenty of air from the vents. I don't think it's icing externally. I'm not getting any wetness or condensation water.

moxy123 said:
What dose the valve look like assuming it is an expansion valve?
Click to expand...

Looks exactly like this:
EX-EX6076C-700-Map.jpg
 
dbarton said:
If it's an HC product, then it's comparable.

Looking at the Duracool 12a MSDS at http://www.duracool.com/msds/webmsdscylr.pdf reveals this:
Methylethylmethane 15-40% (the common name is Butane)
2-methylpropane 30-60% (known as Isobutane)
dimethymethane 40-70% (made from methanol and primarily used as a solvent and in the manufacture of perfumes, resins, adhesives, paint strippers and protective coatings)

Maybe pure propane is just too damned strong and a blend of some kind is the way to go.



I began this 'experiment' with about 11 oz and have reduced the charges down to 5 oz. I don't see how going the other direction will help, since it appears less propane is needed to bring evap temps up from the freeze threshhold.

Can anyone support an argument for more than 11 oz?
It typically brings pressures up by quite a bit. Low side with this much was 40 to 50 psi and high-side was 220 to 250.
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Well if your pressures were like that at 11oz's I'd say your system might not be able to handle pure propane, just freezes up too easy without some modification.

Duracool 12a is good stuff, their blend doesn't autoignite until ~1600F and is stenched so if their is a cabin leak you would smell it quickly. Should cool slightly better then R12 and much better then R134.
 
25psi said:
Well if your pressures were like that at 11oz's I'd say your system might not be able to handle pure propane, just freezes up too easy without some modification.

Duracool 12a is good stuff, their blend doesn't autoignite until ~1600F and is stenched so if their is a cabin leak you would smell it quickly. Should cool slightly better then R12 and much better then R134.
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You might be right.

Was reading the Duracool site and saw this:
A system running too cold can indicate that it has been undercharged. Check the pressures to determine whether or not the system has been undercharged. A DURACOOL? pencil gauge or the Duracool? Low Side Pressure gauge can be used to check the low side fitting psi. If the system is undercharged the pressure will generally read less than 28 psi. Low side pressure should ideally be in the 28-45 psi range.
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This would be an argument for more than I'm using. For a 2.8 lb R12 system like mine, they recommend 1 lb of Duracool.

Duracool 12a is $11 per 6 oz can. Can't hurt much to try it. I'll order a few cans and try it if I haven't cured the existing setup by the time it arrives.
 
The coil part at the end is the temperature sensor that goes on to the evap.

Where does the fitting on the end of the tubing go, I forgot?

The propane is not freezing that is for sure unless you are at -250F, doubtful.

Again in more detail, the air is cold from start after sitting and then gets warmer after running? What temps?

What are the high side pressures through all this? That tells the story and where to look. :nod:
 
moxy123 said:
The coil part at the end is the temperature sensor that goes on to the evap.

Where does the fitting on the end of the tubing go, I forgot?
Click to expand...

It goes to a nipple on the outflow tube coming from the evap. It's an equalizing tube I believe.

moxy123 said:
The propane is not freezing that is for sure unless you are at -250F, doubtful.
Again in more detail, the air is cold from start after sitting and then gets warmer after running? What temps?
What are the high side pressures through all this? That tells the story and where to look. :nod:
Click to expand...

I appreciate the attention....
I've been keeping notes from the beginning.

My first charge was 11 oz. Low side: 30. High side: 250.
Vents at idle immediately after charge: 38-40 F with AC on low setting, fan at 2, ambient was 72 F. At one point while on the freeway, vents dropped to 35 with AC on medium. I set it max and closed the recirc damper for a few minutes and temps dropped to 27 before turning it off.

As I have reduced the charges (8.3 oz, then 5.8 oz), high side pressure has dropped. Most recent was 170 psi. After sitting for many hours, vents will still be 40 F with AC set to low, fan at 2.

Today about noon was the last drive I did, first use of AC today. Ambient was about 83 F. Got about 15 to 20 min of 40 F vents before it began warming. Once it begins warming, it takes about 10 minutes to warm up to ambient or near ambient. Sometimes it will still cool a couple degrees below ambient for another 10 minutes or so, but eventually the vents will be ambient.

Does that answer your question?
Dave
 
Most of it. The added gases of Duracool will help but it still should work with propane and cheaper for testing I think, not sure though.

Your high side is too high especially at those ambients, it should be quite a bit lower then Freon r-12. I would think 150-200 psi, you have no load at 72 F and those pressures should be seen on a hot day with high cabin load. When the condenser temp goes up the high side goes way up this is why a big condenser is needed for cooling.

If you had 27 F coming out the ducts then you had it even cooler at the evap so way too cold and it is definitely freezing up on the outside as that is well below the dew point to trap water and freeze it, this for sure is wrong. This may be one symptom of many tied to one problem. The duct air temperature should be a few degrees warmer then the evap so you want to see 38-48 or so there, closed circulation of course and after the cabin is cooled down if hot.

Just to make sure you know A/C is designed to cool when it is only so cool at ambient not more so if it is too cool outside you will start to get out of range readings. Generally below 68 no one uses A/C. , but it does work a bit in the defrost mode.

What were your low side readings along with these readings during the failure process.


Warning never walk down any aisle in a hardware store that has tens or hundreds of propane torch refill cans as they may explode at any time causing instant death.

This warning has been paid for by the Dupont Freon Company and certified Freon technicians every where. :rofl:
 
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moxy123 said:
Just to make sure you know A/C is designed to cool when it is only so cool at ambient not more so if it is too cool outside you will start to get out of range readings. Generally below 68 no one uses A/C. , but it does work a bit in the defrost mode.
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Yes, I know. Been working on this for weeks waiting for warmer ambients, but the weather hasn't been cooperating.

moxy123 said:
What were your low side readings along with these readings during the failure process.
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When cooling well, low side was 30. As it began failing, low side gradually dropped. When the vents reached ambient, low side would be at zero.
Edit: And if I wait a short time (an hour or three), and try it again, low side will be very low, below 10 and will of course continue downward again to zero. The only change is after waiting an extended time... more than 6 or 8 hours. The best performance is after the car was sitting all night.
Dave
 
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The compressor is definitely working as you have a good differential pressure reading.

There is a restriction at some point from the output of the compressor to the expansion point. Too much gas/liquid on one side that is why the high pressure is reading so high and too little gas on the other side that is why it is so low.

If the expansion valve is opening too much at start that would explain the low temperature evap in the beginning and then closing off too much the excessive restriction and build up on the high side.

Find a little info on the expansion valve you have from the Internet and what the lines do to verify its operation, I am a little weak there.

The freezing up of the evap would do this, are you sure that is not what is happening?
 
example:

When starting the car after sitting and turning the air on the expansion valve releases liquid propane into a high volume area, evap coil, where it expands and takes in heat. At that point is the coldest temperature in the system and the sensor that controls the expansion valve is close by. As the temperature drops below freezing ice begins to form and surrounds the area blocking air flow, it does not take much. The rest of the coil also can start to freeze but less so as you move from the expansion point.

It is possible that you can have a closed loop where the small area is very cold, no air flow there because of ice, keeping the expansion valve in restriction because it is so cold by the sensor. The rest of the coil is quite warm and air is still blowing through without any restriction. This would set up excessive high pressure on the high side and very low pressure on the low side with little cooling.

Check the vapor temperature curves of propane compared to that of the Duracool and r-12 and see if the temperature is different and that would explain the other additives with Duracool. There are ways to correct the expansion problem but if that does it I would just buy Duracool, I am sure they publish the data. If they are the same then more thought and that is not a problem either. Lowering the amount of refrigerant will lower the temp but kill your efficiency at hotter ambients.
 
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One other point:

I was doing a little reading and the vapor-pressure curve for propane is closer to r-22 then r-12 so the above may very well be the issue. A second point I ran across is what really is in the can of fuel you have, off the shelf propane fuel can be quite a mix and have a good amount of moisture in it.

My guess it is the quality of gas or mixture that is your problem.
 
moxy123 said:
example:

When starting the car after sitting and turning the air on the expansion valve releases liquid propane into a high volume area, evap coil, where it expands and takes in heat. At that point is the coldest temperature in the system and the sensor that controls the expansion valve is close by. As the temperature drops below freezing ice begins to form and surrounds the area blocking air flow, it does not take much. The rest of the coil also can start to freeze but less so as you move from the expansion point.

It is possible that you can have a closed loop where the small area is very cold, no air flow there because of ice, keeping the expansion valve in restriction because it is so cold by the sensor. The rest of the coil is quite warm and air is still blowing through without any restriction. This would set up excessive high pressure on the high side and very low pressure on the low side with little cooling.

Check the vapor temperature curves of propane compared to that of the Duracool and r-12 and see if the temperature is different and that would explain the other additives with Duracool. There are ways to correct the expansion problem but if that does it I would just buy Duracool, I am sure they publish the data. If they are the same then more thought and that is not a problem either. Lowering the amount of refrigerant will lower the temp but kill your efficiency at hotter ambients.
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The closed loop theory makes sense, but I'm puzzled that it can take 6-8 hours for the expansion valve to return to normal operation. It must be like super-ice.

Since I have already moved the sensor (called the "bulb" in TXV language) away from the evap surface and placed it on the outlet tube, I'll leave it there are try again tomorrow.

Would you venture to guess what high and low pressures you would expect to see if operating correctly?
 
If it really takes 6-8 hours to reset and it is ice then running the fan on heat with the A/C off should lower that time to much less, a test for water freeze somewhere. If you have propane that has moisture in the new can you will never get rid of it so maybe it is freezing up in the line itself. A new dryer will suck up a lot though but not forever. Again hot air from the heater at the floor level should heat that up quick also.

I know the high side runs less with hydrocarbons then r-12 which is a very good thing. At that ambient r-12 should be around 150-200 psi with propane maybe 10-20% less, just a good guess. The low side should go down about the same I think but again a guess.

I am not going to guess about the bulb as both places make good and bad sense.
 
moxy123 said:
If you have propane that has moisture in the new can you will never get rid of it so maybe it is freezing up in the line itself.
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This is the purpose of drawing a vacuum across the system, no? To lower the pressure in the lines to boil off moisture?
 
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