My '84 XJ6 is having all manner of problems with the cooling system, but I think I'm figuring out most of it (like the crack in the expansion tank . . . ).

The one I'm having problems with is why the heat is ALWAYS on. I have the therm set to 60, and the fan set to off (although any other setting doesn't matter). Hot air continuously blows from the vents.

I'm assuming this is the part I should be looking at:



What do I need to be checking for?

TIA!

 

That's the heater valve. It should closed when max cooling is called for but may be open for any "blend" of hot/cold air to maintain cabin temp. The principle of the climate control is that the compressor operatesd in all modes and all incoming air is cooled first then heated as necessary.

These valves often seize. See if the little lever arm will move manually and/or have a help adjust the temp control from max heat to max cool and see the the heater valve respsonds.

With max cooling called for there should be vacuum to the valve, by the way.Just put your thumb over the end of the vacuum hose to tell. What's the condition of the vacuum hose, by the way?

Does your compressor operate?

When you adjust the temp knob to you hear a faint whirring behind the dash? You should.

When you call for max cooling does the air come out of the central dashboard vent? It should. If it doesn't the system doesn't recognize that you want max cooling or, if it does recognize the request, it cannot comply due to a fault.



Cheers
DD

 

Thanks for the input, Doug. I didn't feel any vacuum in the hose.

Adjusting the temp gauge from the coldest to the hottest did nothing, and I could hear any servo action. I was trying to find the amplifier, but it seems to be pretty elusive.

 

Did you mean to say "I couldn't hear any servo action" ?




Sorta buried in the mass of wires behind the console's left "cheek panel"

Cheers
DD

 

Lol. Yes, I meant to say couldn't. I swapped out all the fuses related to the heater, as well. I'm going to assume that the AC is dead on an '84 anyway . . .

I pulled the left panel off and dug around in there, but I'm not sure what I'm looking for. From what I've read the amplifier should look like a big inline fuse. The Haynes manual I picked up is disturbingly quiet on the subject.

 

The original amplifiers ar square-sih....'bout the size of a pack of cigarettes. Some of the aftermarket replacements are about the size and shape of a shotgun shell.

No whirring suggests a dead amp or dead servo....the amp being much more common but it's a expensive guess.

Fuses: you found and replaced all *four* fuses, including the one on the amplifier ground wire?

Cheers
DD

 

Four? I replaced the 15 and the 50 in the right side fuse box. If there's one inline with the amp, where is number 4?

 

Clipped to the right side of the heater case, inline fuse, behind right side cheek panel. I think the wires are brown and brown/yellow


Cheers
DD

 

Hmm... The only online fuse I found on the left side didn't seem to be connected to the amp (which I'm assuming is the black box with several leads plugged into the it. The fuse was a black why that looked like it was supposed to be grounded, but it the connection had corroded and snapped off.

Am I correct in my observation that there is only one inline fuse on each side?

EDIT: This entry was typed on my iPhone. Please excuse the horrible grammar/spelling.