When I turn my A.C. on, I can hear the blower I believe turn on nice and loud. However, no air is coming out of the vents no matter what setting I use. I can feel cool air barely creeping out of the vents. Any advice on where to start and which way to go on trouble shooting?

You're probably having issues with the vacuum solenoids that open/close the vent flaps.

Go here and download the documentation that outlines the AC system:


http://www.mediafire.com/download/b7...ing+System.pdf

Mr. Everson,


Thank you for your response, reference materials, and for a sense of direction. I didn't want to just dive in anywhere and risk making matters worse. I will give it a gander and see where that takes me. Thank you for your time and knowledge.

Hi Roob0481,

Rob's suggestion that you may have a flap problem is a good one. On your '94, the blend flaps are powered by electric gear motors, and the center vent and demist flaps are operated by vacuum. The photos at the links below may supplement the document Rob posted and help you understand how the flaps work:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page


There are a couple of other possibilities:

First, the system is designed so that two blower motors fire their air streams toward the center of the dash, and the meeting of these opposing air streams is what pressurizes the air that comes from the vents. If one of the blower motors has failed (very, very common), the remaining blower cannot create anywhere near the proper pressure, and you will feel little if any air flow from the vents. You can pull one blower motor fuse at a time to see if only one of your blowers is running.

Secondly, there is a seam in the foam plastic on the back side of the dash near the windshield that is known to separate with age, allowing much of the air pressure from the blowers to leak out behind the dash, significantly reducing the air flow from the vents. I believe this is more common on the earlier XJ40s, but it could be part of your problem, especially if you also have one dead blower.

The blower motors and speed control circuitry can usually be rebuilt. Search this forum and the Jag-Lovers.org XJ40 forum and eBook for information on rebuilding the speed control circuit and replacing the two relays inside the blower housing. I have been able to free a seized blower motor by working penetrating oil onto both ends of the shaft, until the shaft would turn freely, then following up with a light machine oil like 3-in-1 oil for a longer-lasting lubrication than penetrating oil on its own. Do not disturb the squirell cage fan because it is balanced at the factory. Use a straw to feed oil onto the shaft of the motor at the fan end.

Cheers,

Don

I concur with Don's points, both of which has happened to me as well.

Start the vehicle, set the AC on high, and place your hand on both blower assembly's to ensure they are running. If you are unsure, before starting the car, remove the blower fuse for whichever side your inspecting , then start the vehicle and feel if there is any difference to the touch.

In regard to the dash separation, it does happen and a significant amount of air does escape and is channeled down the firewall on the backside of the dash. Before you entertain removing the dash, do the other trouble shooting suggestions first.

Don B.,


I can't express the gratitude I have for the knowledge and guidance you passed on in your last post. Your and Mr. Evenson's references and willingness to teach are way more than I expected to receive. Thanks to ya'lls efforts and references, I have a absolute sense of confidence in resolving this issue. Hats off to you gents.