Heat only works on high.
 

As stated above, the heat only work on high and is only coming out of the defroster vents. I wasn't sure where to start, so I went to the junk yard and got a whole new manifold (not sure what else to call it, rather the thing under the radio with the dials). Unfortunately that was a no go, but worth the shot for a few bucks. I know there is a relay for this component, not sure if it's that or what, but I'm open to suggestions rather than just throwing things at it. Thanks for your time.
99 cherokee.

Usually when you can only get High out of the blower it's the blower resistor block bad and should be replaced.


Air out of the defrost vents only is usually a vacuum leak. Most leaks occur in the engine bay. You should check all vacuum tubing in the engine bay from the intake manifold to the vacuum reservoir under the right front bumper end cap.

Click the link to get photos of the vacuum system in the engine bay.


Click on the image to make it larger.


https://picasaweb.google.com/ken384/...eat=directlink

^ What he said ^

Same thing happened to my 2000 XJ last year.... changed the blower resistor block and good as new. Take out the glove box and it's in the heater casing accessed by removing a couple of bolts... I used an extension on my socket. Bought the part from Advanced Auto parts with on-line coupon for about $30