76 XJ6 US
I'm trying to fix my AC and Heater and need some pointers on where
to begin. Sitting in the car with the ignition turned on but engine
off the fan only runs in the DEF position. Moving the temp set from
hi to low does not produce any sound of servos or flaps moving. I
think the AMP is on the passenger side section of the console. I am
planning to take the panel off and put 12V right to the servo. It
was explained to me to unplug the AMP connection and get ground and
12V to the business side of the connector to see if that moved the
servos indicating an AMP problem. Does this AMP have anything to do
with running the circulation fans too? I don't want to get myself
in deep doo with the wiring inside the console. Are there other
areas I should be checking. Is the defrost fan seperate from the
regular cabin fans? Are there fuses to check? Where might they be?
I've got a parts and service CD but it's not real clear about
troubleshooting in this area. Any and all advice greatly
appreciated.
Submitted by jam@ispwest.com on Wed, 07/13/2005 - 20:18
I don't know a thing about the Series 2 XJ a/c system, but if it's anything like my Series 3 XJ system, there's only two fans, one on each side, driver's and passenger's, 4 speeds each fan. I would start there by removing each Fan cleaning them good and testing them; in my car this entails removing the two housings which contain the fans, not an easy job and a very delicate procedure I should add, easy to break the incoming air flaps, (you need to wedge the flaps in the open position during removal), and I would remove the two front seats entirely to be able to lay on the floor with your head facing up to reach the 3 nuts with a 10" extension and a 11mm socket and ratchet. You might also need a "wooble" socket. This is a serious dismantling job but it is mostly mechanical, not wiring. If the fans test ok (by applying 12V from the battery), then you move to the electronics. In my car there is a fuse in a brown wire located next to or near the battery. Also in that area there is a check valve which affects the vacuum of the a/c system. Those are known to get stuck preventing any vacuum. There is a large Relay on the driver's side of the center console, which is usually the cause of the fans not running, this large Relay is really 4 relays inside it. The original paper Manual says it best: "Test By Substitution". (referring to the Servo, Amplifier, and the many other sensors involved in this system). But that is not always possible so troubleshooting is mostly trial 'n error. As a personal comment, when these systems are working at their best, they are the best a/c system I've ever experienced in any car. It's almost like an aircraft system, pressurizing the cabin and all. Good luck and go slow.