AC causes rough idle

Easily noticeable when fully stopped and engine at idle, as long as the ac is on then the engine will strain every five seconds or so. It's like a rough idle every four or five seconds. If the ac is turned off, there are no problems.

Could this be that the ac compressor is cycling on and off too quickly? Perhaps I need to get a gauge and fill up the refrigerant... maybe if there is not enough refrigerant it will cause this? Or does someone think the cause lies elsewhere.

Thanks in advance,

That is the AC compressor cycling on and off. This is normal.

You might want to get your AC system topped off so it won't cycle so often. Constant cycling is a sign of low refrigerant.

Thanks! I'll try filling up the freon.

Well, it is more than likely R134a.

Is there an easy way to get the compressor to stop cycling on/off while I'm adding the freon? I read in the Haynes manual that you can only add the freon while the compressor is on. They say you can rig a jumper cable to force it to stay on, but they don't go into any details about how to procure the jumper.

We have two Blazers. On our '95 I just pulled the trigger on the freon can when the compressor was on and released it when the compressor was off. After about 5 minutes it built up enough pressure that it stayed on constantly. And man, was that ac working good and cold! Yay!

On our '97 Blazer, I wasn't so lucky. Every 6 seconds the compressor would turn on but only be active for about 3 seconds. I spent over an hour trying to fill it up and went through 1.5 cans without getting enough pressure in there to stop the compressor from cycling on/off. I want to purchase more cans but I'm wondering if there is a simple way to keep the compressor on during this.

Thanks in advance.

You have the AC on MAX and the fan to full while filling the refrigerant through the low pressure port.

Interdynamics has some kits at your local autozone to do it.

And by the way, it isn't freon bud, it is R-12 for the older systems and R-134a for all new systems after 1993 or so.

Also, the cycling will stop once you start to add refrigerant.