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Using Propane in Volvo AC

25psi said:
Sounds like you need a low pressure cutoff switch. Compressor should cycle off below a certain pressure to prevent the evaporator from freezing up.
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Possibly. It would have to be adjustable to be finely tuned. High pressure side runs in the 150-180 psi range and is very stable. I'm wondering though if a switch would simply shut down the compressor repeatedly, every time it tried to pressurize the line, rather than regulate smoothly. That would be bad for the compressor.
 
chris740 said:
My mistake on fully synthetic...
My temp readings were 52 on 134 and 45 with this..so no...it's colder
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Ok, I'll give you the benefit of the doubt. I wonder what makes it "synthetic" if it's designated as R134a in the MSDS. And what would make it cool better?
 
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.

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.
 
I don't know much about the refrigerant but I can tell you that the copper line from the expansion valve goes to in front of the evaporator inside the climate unit. Nothing special about it's location other than in front of the evaporator.
 
Dave, R134a is the refrigerant of choice if you ever want to get the system serviced. Propane is explosive and if you have a pinhole leak inside the passenger compartment, it could explode. Propane may be illegal in some states for automotive use. Any reputable shop will sniff your system and if you have anything but R134 inside, they will not service it. Any other mix besides R134 will contaminate recovery systems and insure that performance is degraded. For the sake of saving a few pennies, safety and a/c performance is sacrificed.
Many have touted using these other mixtures, mostly those who are selling them.
R 134 conversion kits use a thermostatic expansion valve(TXV) that is specific for that gas. Initially, when conversions were started from R12, the thought was that major components must be replaced. This has changed, and many only replace receiver/drier canisters, o-rings and use a quality ester oil. Ester oil is compatible with R12 oils, while PAG oil is not. Also, use Ester oil that is in a can-plastic bottles can allow moisture seepage through the container. Water is the enemy and can only be removed by vacuuming down a sealed system.
If all of these instructions are followed, and no leaks are detected, R134 can absolutely replace R12 with fantastic results. I have done Volvo conversions with TXV systems and fixed orifice systems with good results. Personally, I think it is false economy to use anything but what the factory recommends.
 
The bourdon tube on the expansion valve senses the temperature at the outlet (large line) of the evaporator. It should be fastened to the outlet as close a possible and insulated from ambient temperature. This regulates the opening and closing of the expansion valve.

It is very easy to over charge a system with R134a. In my experience R134a works very well in a R12 system with an expansion valve, but not as well with a fixed orifice tube.

As far as the use of propane goes, mount an insulate the bourdon tube so the expansion valve can do it's job. If you are still having problems report back with results.
 
Ok, I'll try this... The tube was sitting in front of the evap. It is now zip-tied on the evap outlet tube and insulated. When the system is defrosted (for lack of a better term) I'll try it again and report back. The defrost seems to take as much as 6 or more hours.
Thanks

vlvman said:
The bourdon tube on the expansion valve senses the temperature at the outlet (large line) of the evaporator. It should be fastened to the outlet as close a possible and insulated from ambient temperature. This regulates the opening and closing of the expansion valve.

It is very easy to over charge a system with R134a. In my experience R134a works very well in a R12 system with an expansion valve, but not as well with a fixed orifice tube.

As far as the use of propane goes, mount an insulate the bourdon tube so the expansion valve can do it's job. If you are still having problems report back with results.
Click to expand...
 
This is what is most likely happening.

You are putting in a refrigerant with a lower boiling point which is great as far as colder air coming out but as with everything you hit a limit. You can not run the evap much colder then 35-36 degrees or you will start to pull water from the air and freeze it as it goes through the evap coil and thus blocking the coil for air flow.

You need to adjust the expansion valve to keep the temperature of the evap not any colder then 34-36 degrees F so freezing dose not take place.

Once operating properly then charge the system with pressure and temperature readings based on charts to keep the high pressure to a minimum.

Once this is working that well you will dump a good amount of moisture from the air too so make sure your waste tube is clear.
 
Just a couple semi-related things...

Gwen's R in stock R134 trim will blow 39-41* with 105* ambient temps, with generic Johnson brand refrigerant.

My 90 745T with a 134 conversion including expansion tube, dryer, orings, and a compressor from a stock R134 940 blows 45* at 100* ambient, without having a pusher fan.

I haven't personally tried other refrigerant's, but talking with Justin (tjts1) he swapped Liz's wagon to Duracool and was having an issue with frost blowing out the vents, at 100* ambient.
 
Two things with different refrigerants to keep in mind:

1) They having different boiling points, and must be dealt with. Too low and the humidity is turned to ice and the evap freezes so no air can get through, keep it at 34-36, no lower. This temperature range is sweet for a real cold A/C system as the air is cooled quickly, the heat is removed. If the evap has to run high as in r-134a the air is circulated many more times for the same amount of cooling.

2) The efficiency of a refrigerant can not be changed so using a lower efficiency one in a system designed for a higher efficiency one you will have less cooling.
 
gsellstr said:
Just a couple semi-related things...

Gwen's R in stock R134 trim will blow 39-41* with 105* ambient temps, with generic Johnson brand refrigerant.

My 90 745T with a 134 conversion including expansion tube, dryer, orings, and a compressor from a stock R134 940 blows 45* at 100* ambient, without having a pusher fan.

I haven't personally tried other refrigerant's, but talking with Justin (tjts1) he swapped Liz's wagon to Duracool and was having an issue with frost blowing out the vents, at 100* ambient.
Click to expand...

I think the main problem with R134 in these cars are when they aren't switched to an expansion valve or variable orifice tube. Too much pressure swing between idle and driving.
 
I kind of skipped ahead, so hopefully I am not repeating anything. Why not pick up some r12 off ebay? It just as cheap as r134 (bought 134 yesterday at advance for $13 a can) and it will save you the cost of switching the car over. IMO r12 blows colder.
 
25psi said:
I think the main problem with R134 in these cars are when they aren't switched to an expansion valve or variable orifice tube. Too much pressure swing between idle and driving.
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Nope, changing the expansion tube or expansion valve if needed is proper for correct operation but the size of an r-12 system's condenser and evaporator is too small for an r-134a refrigerant, it will work but is always going to have less cooling.
 
MikeSr. said:
Dave, R134a is the refrigerant of choice if you ever want to get the system serviced.
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I am the only one servicing it.

MikeSr. said:
. . . . R134 can absolutely replace R12 with fantastic results. I have done Volvo conversions with TXV systems and fixed orifice systems with good results. Personally, I think it is false economy to use anything but what the factory recommends.
Click to expand...

How many pre-'90 240s have you done?

And they all got fantastic results... in Georgia??
 
gsellstr said:
Just a couple semi-related things... Gwen's R in stock R134 trim will blow 39-41* with 105* ambient temps, with generic Johnson brand refrigerant.
My 90 745T with a 134 conversion including expansion tube, dryer, orings, and a compressor from a stock R134 940 blows 45* at 100* ambient, without having a pusher fan.
Click to expand...

More semi than related in my experience. Later Volvos have much, much more efficient systems to begin with than mid-'80s 240s. I don't think they can be compared.
 
dbarton said:
Ok, I'll give you the benefit of the doubt. I wonder what makes it "synthetic" if it's designated as R134a in the MSDS. And what would make it cool better?
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I wonder if that's where the synthetic materials come in.....The cans I had had full synthetic on them.Not the ultra synthetic as the site does.Guess maybe some false advertising there.Or a name change..
 
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