Hello out there,
Has anyone had a problem of the A/C having a mind of its own? Everything seems to work fine then it decides to switch from cold to hot! I note the in car temp sensor under the crash pad has a "y" branch in the tubing that goes no where. Not sure whether the open tube is supposed to be connected to anything, plugged, or what.
Is there an easy way to test the logic/sequencer without the factory test set?
Thanks
Dick
thigpenraterols.com

Submitted by dougdwyer1@com… on Thu, 09/11/2008 - 12:07

I'm not aware of a DYI amplifier test, per se, but the Jaguar ROM/Service manual has a fairly extensive trouble tree that might help isolate the fault. All such testing/diagnosing, of course, is academic unless it is carried out *when the fault is occuring*.....so if your's is a come-n-go issue you'll need to catch it in the act, so to speak.

Cheers
DD

Submitted by NE40-29744 on Thu, 09/11/2008 - 11:35

Thanks Keith
I'll check them out.
But is there a way to test the amplifier before I start shopping for a replacement? Is the only way to test it the Jaguar test set?
I already have a of the heartburn you mention!
RKT

Submitted by keith.loretta@… on Wed, 09/10/2008 - 22:01

The redesigned version is the shotgun shell looking amplifier, and reported to be better than the original. When you start checking out the prices of the original your going to get heartburn like you've never had before. Now, for a more agreeable price, check out Caulfield Jag. Their in Austrailia, and shipping was only 3 days. They have a nice website. www.caulfieldjag.com.au/home.htm. Been about a year since I got mine, and been working like new ever since.

Submitted by dougdwyer1@com… on Thu, 09/04/2008 - 12:20

The open-ended pipe is correct. The other end of the pipe is connected to the air flow ducting above the driver's feet. The idea is to create a venturi (?) effect, where air is drawn across the sensor via the open ended pipe.

The cheek panel is at the forward end of the console, where the black air deflector for the footwell is located. Remove the two screws holding the deflector then pull the cheek panel forward a bit to release it.

A faulty amplifier could also cause inoperative footwell vents...as could a number of other things. The amplifier takes information from the two temp sensors, the temp selection dial, and the mode switch, and then commands the servo.

The servo....which is what makes the whirring noise when you operate the system....is what actually operates the blowers, flaps and vents via a complex scheme of electric and vacuum switches.

Cheers
DD

Submitted by NE40-29744 on Thu, 09/04/2008 - 11:59

I'll check that. (If I can find the "cheek" panel!!!!) Also I don't believe that the footwell vents ever open. I can't force them to operate but there is good vacuum. Any idea about the in car temp sensor? I just can't believe there should be a pipe going nowhere. It would bypass the sensor to me and cause wrong in car temps.
RKT

Submitted by dougdwyer1@com… on Thu, 09/04/2008 - 10:25

The climate control system is a bit tricky and there are a number of possibilities here.

By far the most common culprit when the system start going a little crazy is the amplifier. Its behind the console's left "cheek panel" and has a round connector with about a dozen or so wires. You can try Ebay or the Jag specialty suppliers for a new or used one. Some outfits are selling a redesigned version.

Before spending any money, though, take a peek at the vacuum hose to the heater valve. No vacuum = heat, so if the hose has a little split, or collapses under vacuum, it might be a problem

Good luck
DD