AC SYSTEM CAPACITY,FOR FREON - 1991 Buick Regal

Freon goes in the ac system and is adjusted to an operating system pressure for the gas in use. If you need to add gas then you have a leak so it would be a good idea to visit an accredited ac specialist shop to find and fix the leak and have the correct amount of gas added.

Well the blend door theory would work if the ac never got cold. But you say it starts out cold and then gets hot.
Its possible the system is freezing up due to lack of air flow thru the evaporator, or a blockage in the freon lines.
You would need to watch the high and low pressure gauge readings as the system gets warm.
You may need professional help for this.

check high pressure with a proper machine and see how many bar you have ,think compressor may be on the way out .

Check fuses and AC relay, check system pressures with AC manifold gauges to determine system charge capacity. If it is below sensor limit on freon, the comp. clutch will not kick in. I hope this helps.

Below is a guide to troubleshoot and check system function. This can be done by most folks.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Remember the flow for the a/c system is :
1. From the compressor a high pressure (HP) gas goes to the condenser in front of the radiator.
2. From the condenser a HP liquid goes to an expansion device (orifice tube or expansion valve)
3. From expansion device the low pressure gas enters the firewall to the evaporator.
4. From evaporator the low pressure liquid/gas mixture goes through the dryer back to the compressor suction.

Below is a guide to troubleshoot and check system function. This can be done by most folks.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Remember the flow for the a/c system is :
1. From the compressor a high pressure (HP) gas goes to the condenser in front of the radiator.
2. From the condenser a HP liquid goes to an expansion device (orifice tube or expansion valve)
3. From expansion device the low pressure gas enters the firewall to the evaporator.
4. From evaporator the low pressure liquid/gas mixture goes through the dryer back to the compressor suction.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Below is a guide to troubleshoot and check system function. This can be done by most folks.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Means low freon capicity because of a leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch. Connect a new can of freon
and fill to system capacity.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 30 to 38 psi..

Remember the flow for the a/c system is :
1. From the compressor a high pressure (HP) gas goes to the condenser in front of the radiator.
2. From the condenser a HP liquid goes to an expansion device (orifice tube or expansion valve)
3. From expansion device the low pressure gas enters the firewall to the evaporator.
4. From evaporator the low pressure liquid/gas mixture goes through the dryer back to the compressor suction.

Check to see if A/C clutch is engaging. If it is not engaging, the compressor is not starting which will prevent the freon from being sucked into the system.

Look at the front of the ac compressor and have someone turn on the ac from inside the car. The front of the pulley(clutch) will spin when turned on.

If it does not spin, the low pressure switch (LPS) is not satisfied. Meaning there is not enough freon in the system to operate the system. Probably means a significant leak.

The LPS can be jumpered to cause the compressor to run (clutch to engaged) which will draw the freon in the system.

The LPS is usually a two wire sensor on the suction of the compressor. (between evaporator and compressor) Unplug the sensor and install a jumper, this will engage the clutch.

However, if it is empty the leak must be repaired.

The capacity of the ac system will be on a label under the hood, do not overfill. Probably about 2 lbs. Local parts stores (Auto Zone and Advance) will have freon with stop leak. This may help the leak. They also make a freon with a UV dye. I always add a single can with dye so that if stop leak does not work I can find the leak in the future.

The system should be filled until suction pressure is about 36 psi.

30oz