Hello fellow XJS'ers,

Morris (89 XJS V12) needs freon. It's been empty for way over five years, and I'd like to see what, if any, leaks he has. So, as the compressor clutch won't engage due to no pressure, how do I engage the compressor clutch so the AC system can suck up some freon/oil/stop leak? Or do these cats have a system where you put some freon/oil/stop leak and the clutch will engage?

Eskr

 

On most ac compressor clutches, if you jumper positive to the clutch terminal directly the clutch engages.

But, checking for leaks only involves adding some freon through the charge port and checking with a leak tester. The freon will normally migrate to both high and low sides. You do not need a full charge to do leak testing.

 

Thanks for the info. On a normal car I could probably run a cable from the battery to the compressor. Yes, on a normal car. This is Morris, he doesn't like normal, does he?

So, any suggestions where I may find a positive contact point to use? Also, if this is any help, I found the compressor relay switch, but I'm not sure which cables to connect and bypas the relay so the clutch engages.

Eskr

 

you dont fill with gas to check for leaks.............,

you place the system under a vacuum , and if it holds, then you have no leaks

then whilst in vacuum and holding , you open the system to a bottle of the desired gas which is sucked into the system under the vacuum

adding gas is expensive just to have it leak to atmosphere if the system is faulty

plus, here in the UK and probably internationally it is illegal to knowingly let CFC's and such like into the atmosphere , and only a licences operative should work on the system


BB

 

Attempting to hold a vacuum will let you determine whether a leak exists or not. However, it does not permit locating the leaking component with a leak detector.

A full charge is not required, only enough for the leak detector to function properly.

 

The output pole of the relay should do the trick as it should be directly connected from there to the compressor clutch. You'll have to confirm from electrical diagrams.

 

Sooo...I got my AC working! But Morris wasn't going to let me do this without a fight!

First thing was finding a positive point with which to engage the clutch. I found a always-on (hot) wire on a big relay with five connections on the driver's side under the hood. Made myself a male-female wire harness to go from the live wire to the clutch. The other connection to the clutch was also a wire I made going from the compressor to ground. Just for laughs, Morris decided to let the live wire touch the body, sending sparks flying and scaring me. Nothing damaged, though.

I vacuumed out the system, and much to my joy, it held pressure! Yes! Success! But this being Morris, this was only a set-up to a let down. I removed the vacuum hoses, and wouldn't you know where there was a leak? From the friggin' high-pressure valve. Laughs to be had all around!

After replacing the valve, though, all was well. As a bonus, apparently the auxiliary fan is now working too! So now both Morris and I can be cool as summer approaches.

Thanks to all of you for your input. Let's see what I should work on next!

Eskr