actually it depends on what type of hybrid it is, there are multiple levels of hybrid.

1. A full hybrid is able to move and run the A/C using electric power only drawn from a large nickel metal hydride (NiMH) storage battery. The internal combustion engine (ICE) does not have to start for either as long as there is enough charge stored in the NiMH, as has been pointed out.

Think of the Prius, or any other Toyota or Lexus hybrid.

And no, there is no exact threshold when the ICE will turn on and off to recharge the NiMH when the vehicle is idling. That is controlled by multiple computers and sensors.

2. A partial hybrid must have the ICE running to move the vehicle or run the A/C, even if the vehicle is idling. The ICE will shut off at stops if the A/C is not running.

There are smaller NiMH and electric motor generators than in a full hybrid and they are used to boost the ICE.

Think of the Chevy Tahoe Hybrid.

3. A mild hybrid must have the ICE running to move or run the A/C and there is a very small electric motor generator that boosts the ICE. There may or may not be a very small NiMH.

Essentially the generator restarts the ICE after a stop to prevent fuel waste at idle.

Think of the Malibu Hybrid.

The A/C compressor and the heat pumps (that move heat from the ICE into the cabin to warm it) are not linked to the ICE in a full hybrid. They are in a partial and mild hybrid in some form, depending on the vehicle.

There are variances in even full hybrids on the electric A/C operation. The Camry Hybrid has an “ECON” button that allows the driver to boost the A/C to maximum with additional energy from the ICE. Normal A/C mode runs purely from the stored energy in the NiMH. The Prius, for example, runs the A/C only from the NiMH energy, no matter what mode is selected.

If that doesn’t clear it up, let me know any other specifics.
Should say excellent post. Looking forward to seeing your next one!

actually it depends on what type of hybrid it is, there are multiple levels of hybrid.

1. A full hybrid is able to move and run the A/C using electric power only drawn from a large nickel metal hydride (NiMH) storage battery. The internal combustion engine (ICE) does not have to start for either as long as there is enough charge stored in the NiMH, as has been pointed out.

Think of the Prius, or any other Toyota or Lexus hybrid.

And no, there is no exact threshold when the ICE will turn on and off to recharge the NiMH when the vehicle is idling. That is controlled by multiple computers and sensors.

2. A partial hybrid must have the ICE running to move the vehicle or run the A/C, even if the vehicle is idling. The ICE will shut off at stops if the A/C is not running.

There are smaller NiMH and electric motor generators than in a full hybrid and they are used to boost the ICE.

Think of the Chevy Tahoe Hybrid.

3. A mild hybrid must have the ICE running to move or run the A/C and there is a very small electric motor generator that boosts the ICE. There may or may not be a very small NiMH.

Essentially the generator restarts the ICE after a stop to prevent fuel waste at idle.

Think of the Malibu Hybrid.

The A/C compressor and the heat pumps (that move heat from the ICE into the cabin to warm it) are not linked to the ICE in a full hybrid. They are in a partial and mild hybrid in some form, depending on the vehicle.

There are variances in even full hybrids on the electric A/C operation. The Camry Hybrid has an "ECON" button that allows the driver to boost the A/C to maximum with additional energy from the ICE. Normal A/C mode runs purely from the stored energy in the NiMH. The Prius, for example, runs the A/C only from the NiMH energy, no matter what mode is selected.

If that doesn’t clear it up, let me know any other specifics.

Hybrid cars might not be quite so fuel-efficient when the weather turns hot.

A study by the Department of Energy’s National Laboratory found that hybrids lose up to 27 percent of their fuel efficiency when the air conditioning is running.

Conventional vehicles only lose 2 to 5 percent.

And the hybrids actually get BETTER mileage in the summer because 1) it’s easier for the gasoline engine to keep warm when it’s not running (a warmed-up engine works more efficiently), and 2) the battery is more efficient at temperatures above 50F.

I get around 50mpg in my Prius during the summer WITH the air conditioning on, and around 40mpg in the winter.

First-hand experience beats I-heard-from-somewhere myths every time. If you know anyone who owns a Prius, ask them to show you the car and hear about their driving experience with it.