I have a Volvo 960 and the AC doesn't work while the car is moving. I'm told there's a hole in a manifold somewhere causing it. How can I fix this myself?

A mechanic I brought it to a while back mentioned the issue. My AC works when the car is stopped, but when I'm moving there's no air coming out of the vent. The heater works either way. The mechanic didn't go into detail but said there was a small hole in a manifold causing it.Now here's my predicament. I'm a social worker who does community inclusion services for the disabled. Basically I drive handicapped people around in my car all day and don't get paid much. I had a lady I was working with become severely ill from the heat when I was driving her, so I need to address this right away. But I can barely afford to pay rent, so bringing it to a mechanic isn't an option.I need to fix this right away and I need to do it myself. Is this something that can be fixed with duct tape? I'm pretty handy in general but the one thing I don't know shit about is cars. Where do I start? via /r/cars http://ift.tt/2sO3hX7