Hey everybody, interesting problem for you guys to mull over. I have a 1987 Jag XJ6 that the previous owner put a small block in. I had heat when I purchased the car, but as I was digging underneath the console trying to discover why the wipers weren't working, I decided that plugging in everything that was unplugged could fix my issue, all it did was stop my heater from working. I assume it had to do with the white/cream colored round plug with all the small wires in it, atleast that's what my research leads me to believe. I would certainly like to get the heat functional if not properly repaired asap as the weather in Indiana is getting really chilly really fast. Any help to get the heat to blow as simply as possible would be much appreciated.

 

need more details...does the blower work? If not there is a temp switch on the heater core that controls the fan. When in heat mode the fan wont come until that switch senses heat. You can find two brown wire on the driver side that bypass the heater core temp sensor.


You may want to check this out.
http://andthatsjazz.org/jaguar/skjag...atics-mk21.pdf


Converts are special to me. Most are not done well. The person who converts often underestimates what a monumental tasks it is to do it right so there are usually many loose ends to tie up.

 

The white/cream colored round plug with all the small wires in it on the LHS of the car goes to the Climate Control Amplifier... It controls the heat and A/C in the car.
They can be stuck to all A/C, stuck on heat, or simply not work at all...
There are a few other things on that side that you could have plugged or unplugged that could make a difference..
My guess would be that you have an inoperable CC amplifier...

The heater valve on the stock setup is on the RHS firewall... Looks like a silver mushroom..
Usually when the CC amp is working, it opens the heater valve to let coolant enter the heater core...

You could probably take the heater valve out of the picture all together, and plumb straight into the heater core.. It may give you full time heat..

I can't think of why you would have had it working before, and not now, if the amp was always unplugged...

David
EverydayXJ.com

 

Water valve is normally open unless the climate control amp thru the servo, closes it. Disconnect the vacuum hose from the water valve and make sure it's open, which means the arm on the valve is in
the down position.

 

The blower motor works, it just blows constant cold air. I don't see a silver unit in the heater hose. Just a white valve and a black mushroom shaped object with a vacuum line. If it helps anything both heater lines heating up. Would these cars have a blend valve that I could adjust by hand to make hot air enter the system?

 

I also forgot to mention, I have those white plugs on both sides of the console.

 

The heater valve is an aftermarket, but no cause for concern there. They can be had at Autozone for a fraction of the cost of the OEM, and work the same..

The white connectors on both sides is also normal.. On the left it controls the amp, and on the right it controls the servo... Were both of them disconnected?

Have you ever removed or replaced the dash pad? The in cabin sensor is there, and if not put back in place won't read the cabin temp..

Cheers,
David
Everyday XJ

 

I ended up fixing it by disconnecting vacuum from the valve in the water line then plugging the amplifier back in. Thanks for the help everyone!