Charge A/C on both low and high sides??
05-29-2017, 06:00 PM
#1
Burning Brakes
Thread Starter
Charge A/C on both low and high sides??
I was reading some instructions for charging the A/C on a 997.1. In my past (limited) experience the charging is done only on the low side. However, what I read said the following:
-Do not allow the low-pressure gauge to exceed 3 bar, otherwise liquid refrigerant can get onto the suction side of the compressor and destroy it.
-Add the refrigerant from both connection hoses to the air-conditioning system in the vehicle.
-The refrigerant in the high-pressure and low-pressure lines belongs to the filling capacity of the refrigerant in the air-conditioning system in the vehicle.
I might very well be misunderstanding, but do these instructions suggest to open both the low and high pressure lines when adding the R134a to the system?
-Do not allow the low-pressure gauge to exceed 3 bar, otherwise liquid refrigerant can get onto the suction side of the compressor and destroy it.
-Add the refrigerant from both connection hoses to the air-conditioning system in the vehicle.
-The refrigerant in the high-pressure and low-pressure lines belongs to the filling capacity of the refrigerant in the air-conditioning system in the vehicle.
I might very well be misunderstanding, but do these instructions suggest to open both the low and high pressure lines when adding the R134a to the system?
05-29-2017, 09:03 PM
#2
I'm no expert on this topic but I have added refrigerant to several cars including Porsches which has improved their cooling capacity. I've only added via the low pressure port and imagine that one would need a bit more sophisticated equipment to access the high pressure port.
05-29-2017, 10:31 PM
#3
If you are charging with liquid (supply container upside down) only charge through the low side and do it intermittently - a quick burst of about 2 seconds. Then wait for the system pressures to settle down and then do it again. If you are charging with gas (supply container right side up) you can charge from both ports but only until the high side system pressure rises above the pressure in the container (then the system will be trying to push liquid back into the supply container).
05-29-2017, 10:50 PM
#4
Burning Brakes
Thread Starter
Great information, thanks. The few times of done it on other cars (using 12oz cans with a can tapper), I've always just opened it up and let it flow into the low side port. Most instructional videos etc. show the same technique. Is there something unique about the 997 system that requires the intermittent method?
05-30-2017, 08:52 AM
#5
System should be evacuated (you need to pull a vacuum on the system before charging.
Do wear SAFETY GLASSES, and a pair of gloves. Low temperature refrigerant can damage you. Never work with refrigerants near an open flame (ie. working in a garage in the winter with an old fashion kerosene heater near by).
When you charge LIQUID, CAN UPSIDE DOWN through the high side, engine should be off. If you are using a manifold and hose set, insure the the low side valve is closed.
When you charge GAS, CAN UPRIGHT through the low side, you need the engine running and compressor clutch must engage to pump. If you are using a manifold and hose set, insure the the high side valve is closed. You can initially charge gas through both high and low sides, engine must be off, not much gain in charging rate for a DIY.
Typically you can put in GAS, about 12 to 16 ounces, at which point the pressure you put in the system matches the pressure in the can, so the system will not accept more refrigerant. At this point the low side pressure cut off switch should make contact and allow the compressor clutch to engage and the compressor pumps. Now you can add more GAS through the low side.
To accelerate the speed of adding refrigerant you can raise engine rpms or place the can of refrigerant, CAN UPRIGHT, in a warm container of water, do not use a heat gun or open flame to warm up the can.
Always be aware of how much refrigerant your cans contain, and have a good idea of your bogey (total system capacity), and document what you are doing.
You want to observe system pressures and ultimately charge by P&T (pressures and temperatures).
Stick with the LOW SIDE GAS charging method.
Do wear SAFETY GLASSES, and a pair of gloves. Low temperature refrigerant can damage you. Never work with refrigerants near an open flame (ie. working in a garage in the winter with an old fashion kerosene heater near by).
When you charge LIQUID, CAN UPSIDE DOWN through the high side, engine should be off. If you are using a manifold and hose set, insure the the low side valve is closed.
When you charge GAS, CAN UPRIGHT through the low side, you need the engine running and compressor clutch must engage to pump. If you are using a manifold and hose set, insure the the high side valve is closed. You can initially charge gas through both high and low sides, engine must be off, not much gain in charging rate for a DIY.
Typically you can put in GAS, about 12 to 16 ounces, at which point the pressure you put in the system matches the pressure in the can, so the system will not accept more refrigerant. At this point the low side pressure cut off switch should make contact and allow the compressor clutch to engage and the compressor pumps. Now you can add more GAS through the low side.
To accelerate the speed of adding refrigerant you can raise engine rpms or place the can of refrigerant, CAN UPRIGHT, in a warm container of water, do not use a heat gun or open flame to warm up the can.
Always be aware of how much refrigerant your cans contain, and have a good idea of your bogey (total system capacity), and document what you are doing.
You want to observe system pressures and ultimately charge by P&T (pressures and temperatures).
Stick with the LOW SIDE GAS charging method.