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I have torn apart the interior of my car, replaced all of the wood, added LED lights, new stereo & amplifier, realys, terminal blocks, refinished the interior of the glove box and now installing new heat shield, sound insulation and custom wool carpets. Every part of the water cooling system and A?C system will be brand new. Should I remove the items I have already installed to remove the heater-A/C box before it starts leaking? Please say no.
Are you asking if a now NOT leaking heater matrix should be renewed as a precaution, or
are you asking if an ALREADY leaking core can be changed without removing the entire aircon/heater unit?
Or are you asking something else?
I ended up like this as a precaution (MY 1988). New heater matrix. A good time to also check the electrical installation and the vacuum control elements under the dashboard. It is very well done if the windscreen is not fitted.
Last edited by roman_mg; Jul 25, 2024 at 06:46 AM.
The heating nor the A/C unit is leaking. The weakest link in the water cooling and A/C system is the heater core the evaporator, everything else will be brand new. I am not sure how the A/C works if the evaporator is inside the heating unit. I just spent $5k replacing all of the HVAC equipment including the evaporator in the middle of the dash in our 2017 XC90 Volvo. How difficult is it to replace the heater core? Do they sell new smaller units? What is the manufacturer and part number? I attached a file with a picture. How do you show a picture on the post instead of a file?
Corrosion in the units isn't usually the issue providing the rules on coolant are followed - with the exception of the bars leaks the 'anti freeze' is mandatory then your challenge shouldn't be corrosion but sludge - that said the coolant helps with that too.
AEU1195 is part number for mine (which is an 87) I don't know if they're different, available new here in UK.
Use this icon to upload an image, I'm not sure about size constraints - 14+ MB is too much for an image I think
My dad purchased this car new. I know he always took the car to the Jaguar dealership for repair and maintenance except for the last few years. I will try to have the heater core flushed in both directions and see what it looks like. Would there be any issues with the A/C parts? Is the condenser inside the cabin and has it been known to leak?
Jaguar dealership does ring an alarm or two because standard practice on coolant changes is to throw some nastiness called 'bars leaks' or similar in the system and it clogs them up, don't know if that happened to yours though.
Only issue I know of with the XJS AC is the absence of R12 availability, there are other options but for efficiencies sake the expansion valve needs replacing, don't think I've ever encountered a failed evaporator in any car I've owned - plenty of condensers though.
I am not sure how the A/C works if the evaporator is inside the heating unit.
All incoming air is refrigerated first and then heated if needed. It's simply a matter of channeling the air through the heater core or around the heater core.
How difficult is it to replace the heater core?
Since you have the MkIII system it isn't too bad. The core slides out of the case horizontally; a little trap door at each ands allows this. Instrument cluster is best removed first along with the glovebox but, still, much easier than the earlier style
Cheers
DD
PS-Evaporators seldom fail. Heater cores often do.
If you know what you are doing, the heater box can be removed. However, there is a very large risk in cracking or breaking the evaporator fittings during the removal process, and last time I checked evaporators were no longer available.
I've removed a number of AC boxes from various cars over the years, and I would only touch the evaporator in an XJS if I had already proven it was leaking and needed to be removed. No way would I touch a functioning unit, the risk of rendering it non-functional is too great.
I've removed a number of AC boxes from various cars over the years, and I would only touch the evaporator in an XJS if I had already proven it was leaking and needed to be removed. No way would I touch a functioning unit, the risk of rendering it non-functional is too great.
I think that I would also add that the expansion valve will be tight - really tight, with the engine in situ it is an absolute bear to get any decent access to or purchase on. I replaced my expansion valve when the engine was out as part of an R134 conversion and it was still hard to do, the expansion valve has to come off if you want to remove the whole AC box which is not a job for the timid.
I wouldn't presume to lecture on a rule that I struggle with (not broken do not fix)
Yellow arrow is expansion valve location Good luck getting at it !!!
The trick to removing an expansion valve is the right tool! Normal crows feet are terrible. However, Martin Brand crows feet are very thin and 12 point. Amazing what a difference this tool makes when replacing an expansion valve.
(you can buy a single piece, but the entire set is worth the $200)
I just purchased those wrenches from Amazon. I think they will be a great help. I am going to leave the cabin heater & A/C unit alone and just test the unit before I totally close everything up.
You’ll love them. Despite this photo, don’t forget to put a second wrench on the on the expansion valve itself to hold it still as you back off the connection nut!
For clearance, I did a 3/8” to 1/4” adapter, short 1/4” extension, and then 1/4 to 3/8 adapter.
Last edited by Jagsandmgs; Jul 27, 2024 at 12:29 PM.
Granted my 90 has above average miles on it, but when I replaced my heater core the AC evaporator was absolutely filthy. I cleaned it as best I could(toothbrush, shop vac and spray can AC coil cleaner repeatedly, with rinsing), the hair and dust and foam had also been clogging up the drains now and again, and it's been worlds better since then all around.
The AC is actually quite good on these with both blowers in good order and air flowing as it should through the evap. If I had the dash mostly apart or out I'd certainly pull that box apart and give it a good cleaning and inspection but I wouldn't do it unless I
had a reason. The heater core was an annoyance but it was doable with everything in place. If you pull the seats it's a lot more pleasant on your back.
Change Heater & A/C Unit?
