Air conditioner problem

[John nugent]

2004 79,000 miles. I start my car, let it run a bit. The heat/cool dial is set in the blue (cool) area but the AC button is not engaged, I turn the fan dial to any setting and I feel like the AC compressor kicks in, the RPMs drop some. Why would this happen. Thanks in advance for the help.

[kung fu jesus]

The HVAC fan is needs a lot of current. When you turn it on, the electrical system is loaded. It's not unusual.