The neighborhood catch-all mechanic charged my ac system. Unfortunately the compressor did not engage. He did verify that the compressor had power and that the system held pressure. So I am in unfamiliar territory. I did read the a/c section off the service manual and the Superheat switch and Thermal fuse seemed to pop out to me as reasonable culprits. Is there any common failure points to the S3 ac system that I should look into? Again, thanks in advance. ren

Also, anyone know of a good mechanic in Oakland County MI?

 

Sans a functioning compressor, I am not sure it has a charge!!!

 

You're on the right track. If the system was low on freon, and the protection circuit was working correctly, the thermal fuse will be blown. However....were that the case, the compressor would not have power as you stated.

If the comp has power (and ground) but isn't engaging then perhaps the clutch is on the fritz.

Cheers
DD

 

this!

without compressor running he didn’t charge it!

And as Doug says, if comp has power, the clutch is likely on the fritz, can you spin the clutch by hand? ( with engine off!!) if so, maybe the air gap is too big to overcome an older magnet????? Or maybe just stiff with lack of use.

 

Thanks for the input. I will verify just exactly what he did. I'm a long time customer of this repair shop and it has been a staple of my small town for years. I had a very clear discussion with him regarding the ac system "consuming" the proscribed amount of refrigerant per the jag service manual that I provided him. I'll ask for a more detailed answer on Monday when they re-open. I'll report back. I'll also make a careful observation of the functioning of the climate control system and the flow of air as I ask it for cold then hot then defrost etc. I'll report back. Ren

 

On myJeep, I can see if the compressor clutch engage as the control is moved to call for cold air.

 

Darren,
Find the clutch relay (there has to one somewhere) and hot wire it. That will tell you if the magnet will work at all of if something upstream of it is wrong.
(';')

 

Okay, I took the car to a shop that specializes in auto ac repair mainly for domestic vehicles but shop owner was willing enough to take a look. They opened the shop in 1959.I watched as he hooked his gauges to the high and low ports. He then informed me that it had 50lbs of pressure. He verified that the unit was getting 12 volts. He had me start the engine and set the climate control to its coldest (65 degrees) and the clutch did not engage. He had me shut the engine off. He examined all around the engine bay and found no signs of leaking. He then added 50 more pounds of 134a and had me repeat the above steps and again no cycling of the clutch. He went back to a visual inspection and found wire at the back of the compressor had been disconnected. He believed it to be the high pressure switch although we could not find mention of it in the service manual. He reconnected it and had me repeat my process and this time the compressor came alive ever so briefly the went silent. He had me shut off the engine and tried to manually spin the clutch at which time he pronounced it frozen. He then informed me that I needed a to replace the clutch/compressor assembly and the drier. I asked about the expansion valve and he said it looked relatively new and probably could get by without changing it. Well at least I know what needs to be replaced. I should also state that prior to all of the above, I was able to verify that the climate control system behave as it should meaning air came out of the appropriate vents base on the requested temperature. That was good news.

My plan is to remove and install the drier and ac unit. Is the expansion valve a must too? Should I remove the bonnet? It seems a bit of the wrenching has to take place from the front. Hope it's not too tricky to get the bonnet off. Looks like a 3 man job to me with two on the hood and one doing the wrenching. Also he mentioned not using PAG oil in the compressor but Ester oil as it is more compatible with 134a. I'll look into that after I get the parts off. I see I can get a kit consisting of a new compressor with clutch, a drier, an expansion valve and PAG oil all for $404 shipped to me. I thought that sounded good. I'll check rockauto.com too.

As always, any advice would be appreciated.

 

More of a "why not?" than a must, perhaps. Not expensive. Be very careful removing it, though. If you break the stem it attaches to it'll really ruin your day


IMO, no.

In my experience it can be a real problem realigning the hood and getting the pins to line up properly. The potential aggravation offsets the benefit. Opinions/experiences will vary

Stay with what will protect your warranty.

Cheers
DD

 

Actually, no, there isn't ! Not on a Series III XJ6.

I always wondered why.

Cheers
DD

 

Thanks Doug.

A few more questions for the forum:

? Where would the superheat switch and thermal fuse be located in the engine bay if my '87 had them?

? Does anyone else have a round plug in cap that connects to the lower right back side of the compressor. The ac guy thought it was a some sort of safety cut-off switch. I'll post a picture of this "cap" and it's location on the back of the compressor later.

? I'm considering not replacing the expansion valve because of the concern I now have after reading several severe warning comments. Maybe I'll try CAREFULLY loosening the fittings and see how it goes.

? If removing the bonnet is not straight forward then will detaching the folding bracket allow the bonnet to swing away a bit more without damaging the lower grill where it meets the bumper

Thanks, Ren

 

Ren, many of us have ditched that link completely and wondered why we waited so long.

The grill does not touch the bumper, at least not on my Series 2 so no damage is possible. Only danger is having hood up in the wind.

I kept the link just because, but I have no itention of ever putting it back.
(';')

 

The superheat switch is mounted in the rear plate of the compressor, retainer by a snap-ring or circlip. The thermal fuse is clipped to the compressor bracket.

Late '87s didn't have the superheat switch or thermal fuse. The "superheat" circuit was replaced by a different circuit using an "HSLP" switch-- high side, low pressure. The HSLP system didn't use the thermal fuse.

You should note that the earlier superheat set-up is often replaced with the HSLP type when compressors are changed. The HSLP system is simpler. However, your compressor will either be "Superheat" or "HSLP". They're not interchangeable; you can't convert from one circuit to another without changing compressors (or at least changing the rear compressor plate)

If you replace your compressor go with the HSLP type even if your car was originally built with the superheat type.

That round cap is the connector for the superheat switch or the HSLP switch. And, yes, it's a safety cut-off.

Cheers
DD

 

Okay, here's a photo of the "cap" and the port on the back side of the compressor where the cap plugs into.






A few questions:

? is this some sort of a pressure switch (when the ac guy plugged the cap in, the clutch/compressor did engage for a moment)

? will a new compressor have this port installed or will i have to switch it over

? does anyone know where I would find the superheat switch and thermal fuse in the engine bay

Thanks, Ren

 

Thanks Doug, please ignore my questions as you've already answered them. I should have read your post sooner. Now that I shoved the phone/camera well into the engine bay and got a good photo of the hslp switch, I can see the pinch retainer clip. I believe I can carefully remove the retainer clip, remove and transfer the switch to the new compressor.

I have been lubing all visible union points that I can see with PB Blaster. I hope to begin dismantling all associated parts later today. My plan is to spread the parts removal over a few days to keep my frustration down so I don't break something due to impatience including the tricky expansion valve.

 

? I'm wondering if I should replace the original HSLP switch with the new version

https://www.welshent.com/Jaguar-High...ch-P26006.aspx

 

Right.

But, remember, if that's an HSLP switch make sure you get an HSLP compressor. If it's a Superheat switch make sure you get a Superheat compressor. I can't remember how to tell one switch from another by just looking....but the info is probably out there somewhere. I have a foggy memory that the two switches are a different diameter so they can't be inadvertently mixed-up.

Cheers
DD

 

This time you found the right guy. Methodical. Got to the issue and a dependable fix.

No, do not remove the bonnett. It took two guys and a gal to replace mine!!!!

But, yes, the little "monkey" motion" travel limit. Out with it Mine left decades ago. Not missed at all.

Good work. AC and coooool air on the way....

 

I replaced my compressor and whole AC system like two years go. You have what looks like the Superhett switch to me. I replaced it with the HSLP version which looks very different. In my thread

"Curious AC Symptoms" you can see a picture of the Superheat fuse and where it is located. There's a lot of infor for you in that thread.

 

The switches are very different. The Superheat has a single large and thick male connector while the HSLP has a two connectors in a female socket. The one the poster linked to at Welsh enterprises is the HSLP. The picture posted looks to me like the Superheat one I pulled and replaced.