A/C Issue's!!!!!!

[CapriceBoy214]

Hi.
I have a 1989 Chevy Caprice with a Fuel Injected 350. My vents wont blow. Only the top of tha dash and the vents by the floor blows. Now to the major problem. When I turn the A/C on in my car, it will start to jerk as if it was running out of gas. It have been times when my A/C is off and it does the same thing. Can someone please help. Iwould gladly appreciate it. I have a 6 month old daughter and its HOT in Texas.

[rhandwor]

They have vacuum motors which open dampers. They have a vacuum pot on one end and a shaft linkage which moves the damper.
It sounds like you have a blockage or restriction in the compressor discharge stalling the compressor. Does the belt smoke or is the clutch heating up?
Do you agree with this or is it a motor problem?

[CapriceBoy214]

Well my motor was rebuilt about three years ago. Theirs nothing abnormal under the hood accept a rattling noise once I turn the A/C on.

[rhandwor]

Put a set of gages on it and check the suction and discharge pressure. A 350 should have enough power to run a compressor. I would check the timing if it rattles to much if this is what your talking about.

[CapriceBoy214]

Someone told me before to check my timing because of how my car start and when it gets to running temp it wouldnt start up again.

[CapriceBoy214]

Can anyone else help me too ???
Thanks

[CD Smalley]

You have a vacuum leak somewhere. That's what causing the problems with the vents. Run all of your vacuum hoses under hood and anywhere you can reach under the dash. Especially look for a bad one running to a black ball under the dash.

[silicon212]

I echo CD Smalley's diagnosis - somewhere, somehow, vacuum isn't being routed to its necessary destination. There are a number of causes - the vacuum lines are hard lines and can become brittle and break. Check the condition of these lines (both brown and white) under the dash and under the hood. The vacuum is originally sourced from the intake manifold, and is stored in a reservoir (the black globe that CD Smalley mentioned). Another thing to check is the AC/heater control itself. There should be three vacuum servos under the dash which operate different aspects of the AC system. Make sure that all of the lines are properly attached and that each servo works. You can check the servo by pulling the hose off it, pushing the arm in and then sticking a wetted finger over the line input. If it rebounds or hisses, and you're sure that your finger has a good seal on the line input, then the servo is suspect. Check for plugged lines.

The noise under the hood can indicate a loose compressor belt, a failing compressor or an overcharged system.

[rhandwor]

He needs to be more explicit on what is going on. He may have a leaking intake but the engine would run rough all the time. A chevy 350 shouldn't shake badly when the A-C is turned on. He has two problems one is the damper not changing which you covered but the other is a compressor problem or the engine is always running badly. This he needs to explain exactly what is going on to get it fixed.

[CapriceBoy214]

My engine dosen't shake. I said that their is a rattling noise coming from under the hood. If it is a Vacum Leak how do I fix it. And what about when I turn my A/C on or just my Vents on it start to jerk like its not getting gas or loosing power. I'm sorry I just really need to get this fixed.

[rhandwor]

You may have a plugged fuel filter. For a vacuum leak by a can of carb. cleaner. Spray along the edges of the intake manifold. If throttle body injected spray around the throttle body and around any Pcv hoses. Otherwise spray around the injectors if you have a vacuum leak the engine will smooth out.
Find the hose on the intake supplying the A-C system see if it is plugged and go from their.

[CapriceBoy214]

I just changed the fuel filter and it only does it when I turn my A/C on.

[rhandwor]

A leaking vacuum booster will cause a big vacuum leak. To test this put a bolt in the hose and gun the engine with A-C on. Try it both ways A-C on and off.
Also check the vacuum pot.