AC and Heater Issues Honda Civic 06

Sounds like the system is losing vacuum do to a bad vacuum check valve. Intake manifold vacuum is highest at idle. As you accelerate the vacuum decreases. A check valve is put in the system to hold vacuum under these conditions to prevent temperature door shifting and mode shifting. Some systems also have a vacuum reserve tank in the system too. The operation of the compressor sounds normal. At low blower speed less coldness is being pulled out of the refrigeration system. This allows the pressure to drop, on the low side of the system, to the cut out point and the compressor stops for a few minutes to prevent the system from freezing up. Hope that helps! Jim

Thank you for your input. How would one test for this? I tried googling, but come up with other results that I don't think are correct.

You're welcome. Glad to help. Look for a check valve in the vacuum hose going from the engine to the firewall. It'll be a little round disk like thing. The vacuum reserve tank, if equipped, will look like a square black box, or possibly a round plastic ball. It will have two vacuum hoses hooked up to it! Hope that helps! Jim

How would one know if it actually is the cause of the problem? Replace it? Is there another way to see if the valve is working appropriately?

The check valve is cheap enough that you can just replace it. It's like a $3.00 part. Hope that helps! Jim