87 chevy caprice A/C vent not opening

Open hood , passenger side firewall area, look for a thin,black vacuum line, follow it and look for any breaks or bad connection to its vacuum source. repair as necessary.

Not sure if I'm too late to answer this one, but you're describing a low refrigerant condition. The hissing noise and constant cycling of the compressor clutch are indicators of that. You should recover the system, record how much refrigerant was recovered, evacuate the system (with a vacuum pump), add A/C dye, and recharge the system to capacity. Common leak areas on these vehicles include the A/C condenser (located in front of the radiator), and the evaporator (located inside the dash, and requires complete removal of the interior dash to replace it). If you can't find a visible leak after running the recharged system with dye for several weeks and it starts to blow warm again, you will need to use an R-134a leak detector to "sniff" areas of the system for a refrigerant leak.

Water level perhaps. When you hit the accelerator the water volume increases. Check your water level and make sure that your thermostat is opening and closing properly. Water level I'm thinking

Your control valve for your duct work is having a small problem, its just not opening. The duck system work lid the heat/ac ducts at your home. The only difference is you can control through a vacuum controlled valve where you want the air to flow. What has happened, is the valve has shut the system at the neck( where duct is connected for all the vents) There are three areas that could be wrong. 1- a vacuum line has come apart or broke( they are just made of rubber). The line would have to be replaced. 2- the controlling valve is stuck, and either needs to be unjammed or replaced. 3- your control unit(mounted on the dash, the one you use to adjust everything) has gone out. Being you have an older car(great year for caprice)you also have some cables on the control unit. One of these may have gave way(broke) or the plastic clips that hold them may have snapped. You can manually ope the vents from under the dash. It will be under the center toward the passenger side. You will see the ducts leading back to your control box. you can also see the rads and control lines there. just adjust the arm til you get air in the vents. its a tight fit, smaller hand work great for that. I hope this helps you

The distribution of the air in your car is controlled by little vacuum powered doors in the vent system (inside the dash). You either have a vacuum hose that is disconnected or one of the air valves that runs the door is bad. With the engine running, put your head down under the dash and see if you can hear a hissing noise. If you can, it is a loose hose and just need to be reconnected-not an easy task as there is not much room to work.

The air vents are control by vacuum line and or linkage.

Listen for hiss or feel for vacuum leak under the dash,

Feel for broken linkage(s) that are close to the vents.


WORK BACKWARD if you have small hands to feel out where is the missing link.

Vacuum hose most likely the problem. They get dry and crack open especially near the connections. Check the vacuum and listen for a hissing sound with the engine running. Don't put your hands near the fan!

It sounds like you have a blend door malfunction. Its hard to know the extent without opening your A/C system and looking at the belnd door system. It might be as simple as taking some dash pieces off.

hello , sounds like an air lock in coolant system , drain system and re fill very very slowly , if you think you are filling it slowly enough slow it down even more , also replace thermostat to ensure its opening and closing properly , hope this helps

what if both hoses are hot. and on idle heat comes on but driving it's blows co