Jaguar's XJ-series of cars include a heater that's protected by a fuse. There are two fuse boxes under the hood, on the left-hand side. The larger box has 22 fuse positions and the smaller box has 18. Two further fuse boxes are behind the right and left heel-board trim panels below the rear seat. There is also a luggage compartment fuse box. Troubleshooting a Jaguar XJ6 heater involves checking fuses and replacing relays.
Open the left-hand heel board, rear compartment fuse box and inspect Fuse 12 if the heater won't work. The fuse is rated 10 amps and protects the blower motor relays. Remove it with a pair of tweezers if the special tool supplied is missing. Inspect the fuse for a break and replace it with the same amperage and color fuse if necessary.
Open the right-hand heel board, rear compartment fuse box and inspect Fuse 6 if the heater still won't work. It's rated 10 amps and protects the air conditioning overall. Inspect the fuse for a break, and replace it with the same amperage and color fuse if necessary.
Replace the relay if the heater still doesn't work. The left and right blower relays are in the passenger compartment behind the right-hand side heel board. Pull the relay out of the harness, discard it and replace it with a new one.
