does anyone know why my air conditioning / heat will only come out the defrost and floor?? have a 99 Dakota 2wd. this is run by vacuum and I traced all the hoses I can find with no luck. switch seems to be functioning but I am not sure it is. any help is greatly appreciated.

 

Welcome to the forums!

It sounds like you aren't getting vacuum to the selector switch. The doors default to defrost/mix when there's no vacuum.

Start the truck and let it idle for a minute with the control OFF. Shut off the truck. Then, turn the control to panel (A/C). You should hear the doors move.

There is a check valve in the system. Look for a hard plastic line, about 1/8" near the brake booster. It connects to the check valve. Pull the hard line off and engine running, check for vacuum.

You can also disconnect the vacuum harness from the control. You should feel a strong vacuum at idle.

Hope it helps.

 

00dakdan, thanks for your reply, the doors do not move with engine off. and I have good vacuum at hard line by brake booster, also good vacuum by box under windshield cowl. do you think switch is bad or should I try to see if there is vacuum at switch?

 

Check for vacuum at the switch. If you have it there, the control is likely bad.

Consider a boneyard for a replacement.

 

thank you, I will try that tomorrow.

 

eBay LINK 1997 to 2000 same

exact model needed http://www.ebay.com/itm/1999-2000-Dodge-Durango-Dakota-Manual-Heater-Climate-Control-OEM-/330917009210?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d0c30d73a&vxp=mtr

 

just an update. I disconnected harness a the switch, have vacuum at the black hose only. does this mean control unit is bad?. if so then I will look at boneyard for one. thanks to everyone or their help.

 

The black line is the vacuum supply to the controls.

You could try applying vacuum to the actuators, usually with a vacuum pump to test them but it seems unlikely that they'd all fail.

 

A simple test run the engine a few minutes then shut off

Now twist the selector switch back and forth you should hear the actuators working as you do this as the system has a pressure holding tank that will give you the power to move them for a few times then it will not work.

If nothing happens then you have a vacuum leak a bad holding tank or a bad check valve.

Possibly a bad selector switch/controller

Did you check out my web on this stuff LINK