friends i don't have much knowledge about this, but i can suggest you to get it repair by somebody experienced and professional in this field.

The Air condition definitely would lead to the engine to hold up when a solid load is placed on at idle such as the ac. Just place, it differs the air to the engine to handle the engine Revoltions per minute at idle. If it does not work, the engine will possibly race or wait as running modifications at idle. Due to the fact you purchased a another one, you may as well place it on. I would have examined it to make confident that it was the trouble initially.