loose ac air flow when vehicle accelerates
When I step on the gas the air flow out of the ac vents are reduced to almost nothing and it comes out defroster vents top of dash
Defrost is the default setting when you loose vacuum, so you have a vacuum leak somewhere in the vacuum control systems for the heater/defrost. Make sure the line is not split from the engine to the control head inside the vehicle, if that is good then your going to have to test every vacuum servo motor, supply lines and control valve for a vacuum leak. Yes it can get involved.
Most likely the vacuum check valve is bad. It's in line at the vacuum hose coming from the engine to the vacuum reserve tank on the driver's side fender. It usually looks like a little black or white disc with a vacuum hose connected to each side of it. HTH. -Jim
There is a vacuum canister mounted on your hood. It looks like a plastic ball and should have one vacuum line going to it. It helps prevent this
Looking for a Used Jimmy in your area?
CarGurus has 19 nationwide Jimmy listings starting at $1,980.
Search GMC Jimmy Questions
GMC Jimmy Experts
Related Models For Sale