Jaguar XJ-S V12 Air Conditioning Fix | Diagnosing & Recharging the System

While driving my 1989 Jaguar XJ-S V12 Coupe to the Silverstone Festival 2025, I discovered my air conditioning wasn’t working properly. In this video, I take you through my troubleshooting process under the bonnet, checking key components of the A/C system before discovering the real culprit – low refrigerant gas.

I walk through each diagnostic step, from relays and compressor checks to the heater matrix valve, before re-gassing the system and confirming cabin vent performance with an infrared temperature gun.

If you own a classic Jaguar XJ-S, this guide may help you track down similar issues and understand how the A/C system works on these cars.

🔧 What I cover in this video:
Checking the 10A black relay and A/C electrical system
Inspecting the GM Harrison A6 compressor magnetic clutch
Testing the heater matrix valve operation
Measuring A/C system gas pressure
Safely topping up the refrigerant gas
Verifying air vent temperatures (hot & cold)
Bonus: checking how hot my engine runs!

🛠️ Tools & Parts Used in this Video:
Posidrive screwdriver
Car Aircon Top-Up Recharge Refill R134a kit (inc. gauge)
Additional R134a Refill Cannisters × 2
Etekcity Infrared Thermometer Gun (-50°C ~ 450°C)

📌 Video Index
00:00 - Introduction
00:44 - Overview
04:29 - Checking the 10A Black Relays
05:55 - Checking the Magnetic Clutch on the GM Harrison A6 Compressor
07:24 - Checking the Heater Matrix Valve Operation
09:04 - Re-checking the Air Conditioning Gas Pressure
10:10 - Topping-up the Air Con Gas
12:39 - Verifying Air Conditioning Effectiveness (Hot and Cold)
15:15 - Extra: How Hot is My Engine?

👉 If you enjoy classic Jaguar troubleshooting, repairs, and road trips, don’t forget to like, comment, and subscribe to Too Old Classics for more XJ-S, X356, XJ40, and S-Type R content.

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