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Don't use that crap with the stop-leak in it...
Air Conditioning Help
- Thread starter Boone83K10
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Boone83K10
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sorry I have been gone for a week, I moved into my new home!!! Truck drank copious amounts of gas during the move since it took 1/4 tank to go from one house to another which amounted to 6.28 mpg 
I put R134a in it, no stop leak crap, just straight oil and refrigerant. Has been working great all week.
I put R134a in it, no stop leak crap, just straight oil and refrigerant. Has been working great all week.
chengny
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Quted fropm your OPO:
PS----- the truck has already been converted to R134-A before I bought it. I have no idea if it has any refrigerant in it.
I can almost guarantee you that there was at least some refrigerant still in the system.
This is the reason you were able to bring it back to operational status so easily - the system pressure was never allowed to drop below atmospheric pressure.
The recharging procedure is far more involved when a refrigeration system has been exposed to the non-condensables and moisture in the air.
If the system is open to ambient conditions (fancy term for "has a leak") and the internal pressure drops down to atmospheric for any length of time it will soon become contaminated.
When the inside and outside pressures finally become equalized, the system begins to "breathe" in and out at the leak.
The same leak (usually at the compressor shaft seal) that allowed the gas to escape can now allow air and moisture to enter the piping. This occurs due to the normal fluctuations in temperature.
When the system is heated up (by hot sunny days or just by being in the engine compartment) the internal pressure rises and gas escapes out the point of leakage.
When the engine is shut off (or the weather turns cold) the system cools down, the gas/air mixture decreases in volume. This creates a vacuum (below atmosheric pressure) condition within the piping.
With outside air pressure now higher than the pressure inside the system - moisture laden air is forced into the system (or the vacuum pulls it in - depending on your view) through the leak.
After this heat up/cool down cycle is repeated a number of times (how many depends on the size of the leak and the degree of temperature change) the system is basically all air.
The filter drier will be saturated with moisture and there will be even more moisture in the contained air. The air is non-condensable and when the system is operating it will collect in the condenser coils.
When the system is charged and started:
1. The air will migrate to the condenser and stay there. This reduces the amount of area available to condense the refrigerant. When the refrigerant can't condense fast enough the high side pressure rises and overheats. The compressor loses efficiency and cannot pump down the low side.
Bottom line: the flow of refrigerant through the system is severly limited by the presence of air.
2. The moisture (that came in along with the air) will have ruined the drying capabilities of the filter/drier.
A refrigerant filter/drier has 2 functions.
It has a fine mesh screen to catch any debris that is entrained in the refrigerant/oil mix that is flowing through it.
More importantly, it also contains a tray of dessicant that is extremely hygroscopic (it has a tendency to rapidly absorb moisture)
This dessicant has a limited capacity of how much moisture it can trap and hold. While exposed to atmosphere it will have been "used up".
It can't remove the additional moisture that is contained within the refrigerant/oil mixture that will be flowing through the system.
The moisture will eventually migrate to the metering device (in this case the orifice tube). Due to the sudden temperature drop at the metering device, the moisture will condense and start to form ice. The ice will form at the orifice tube and also within the coils of the evaporator.
Eventually, enough ice will accumulate that the flow of refrigerant is blocked.
Bottom line: again, as with contrained air, excess moisture will severly limit the flow of refrigerant through the system.
Having said all that, if a system is found to have no pressure remaining after an extended period of non-use two things must be done:
1. Replace the filter drier with a new one. Another option - if you're cheap like me - bake it in the oven for a day or two at 250 degrees. This will drive all the moisture out of the dessicant and give it new life.
2. When the leak has been repaired and the new F/D installed, attach a vacuum pump to the HP service port. Pull down to a deep vacuum and keep it down for a day or so. This will evacuate all the air and moisture from the system.
While you still have a vacuum, dump as much freon in to the system as possible. If you can get a couple of cans in, it might even get the compressor to start without having to use a jumper across the LP switch.
PS----- the truck has already been converted to R134-A before I bought it. I have no idea if it has any refrigerant in it.
I can almost guarantee you that there was at least some refrigerant still in the system.
This is the reason you were able to bring it back to operational status so easily - the system pressure was never allowed to drop below atmospheric pressure.
The recharging procedure is far more involved when a refrigeration system has been exposed to the non-condensables and moisture in the air.
If the system is open to ambient conditions (fancy term for "has a leak") and the internal pressure drops down to atmospheric for any length of time it will soon become contaminated.
When the inside and outside pressures finally become equalized, the system begins to "breathe" in and out at the leak.
The same leak (usually at the compressor shaft seal) that allowed the gas to escape can now allow air and moisture to enter the piping. This occurs due to the normal fluctuations in temperature.
When the system is heated up (by hot sunny days or just by being in the engine compartment) the internal pressure rises and gas escapes out the point of leakage.
When the engine is shut off (or the weather turns cold) the system cools down, the gas/air mixture decreases in volume. This creates a vacuum (below atmosheric pressure) condition within the piping.
With outside air pressure now higher than the pressure inside the system - moisture laden air is forced into the system (or the vacuum pulls it in - depending on your view) through the leak.
After this heat up/cool down cycle is repeated a number of times (how many depends on the size of the leak and the degree of temperature change) the system is basically all air.
The filter drier will be saturated with moisture and there will be even more moisture in the contained air. The air is non-condensable and when the system is operating it will collect in the condenser coils.
When the system is charged and started:
1. The air will migrate to the condenser and stay there. This reduces the amount of area available to condense the refrigerant. When the refrigerant can't condense fast enough the high side pressure rises and overheats. The compressor loses efficiency and cannot pump down the low side.
Bottom line: the flow of refrigerant through the system is severly limited by the presence of air.
2. The moisture (that came in along with the air) will have ruined the drying capabilities of the filter/drier.
A refrigerant filter/drier has 2 functions.
It has a fine mesh screen to catch any debris that is entrained in the refrigerant/oil mix that is flowing through it.
More importantly, it also contains a tray of dessicant that is extremely hygroscopic (it has a tendency to rapidly absorb moisture)
This dessicant has a limited capacity of how much moisture it can trap and hold. While exposed to atmosphere it will have been "used up".
It can't remove the additional moisture that is contained within the refrigerant/oil mixture that will be flowing through the system.
The moisture will eventually migrate to the metering device (in this case the orifice tube). Due to the sudden temperature drop at the metering device, the moisture will condense and start to form ice. The ice will form at the orifice tube and also within the coils of the evaporator.
Eventually, enough ice will accumulate that the flow of refrigerant is blocked.
Bottom line: again, as with contrained air, excess moisture will severly limit the flow of refrigerant through the system.
Having said all that, if a system is found to have no pressure remaining after an extended period of non-use two things must be done:
1. Replace the filter drier with a new one. Another option - if you're cheap like me - bake it in the oven for a day or two at 250 degrees. This will drive all the moisture out of the dessicant and give it new life.
2. When the leak has been repaired and the new F/D installed, attach a vacuum pump to the HP service port. Pull down to a deep vacuum and keep it down for a day or so. This will evacuate all the air and moisture from the system.
While you still have a vacuum, dump as much freon in to the system as possible. If you can get a couple of cans in, it might even get the compressor to start without having to use a jumper across the LP switch.
Senck243
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Gotta mess with mine this weekend. Compressor isn't coming on
Sent from hell
Sent from hell
