Here is a favorite topic we have all read about, and some of us have felt the pain. My sob story is this: I used to live in Montana and when I got my 1982 XJ6 it came from Tucson AZ and the heater did not work. I paid a guy 800 dollars to put in a new heater core, and still no heat.


He pulled apart the console and disconnected the vacum hose from the heater valve (brand new valve at the fire wall) and disconnected a few things inside my car and I had VERY MINIMAL HEAT at low fan speed.


I suffered.............. and now I moved down to Arizona so I wanted AC again so I had the mechanic put it back the way it was before he messed with it. My AC isnt very strong now. I want to check the freon (or whatever the refigirant is) with a guage that came with some coolant I bought at checker auto, but I dont see a fitting i can thread on to. What is my coolant in this system, could I just be low on refigirant? Will this guage I have work on my car? It works on my moms 1996 Chevy Pickup, and my old 1994 Ford explorer.

 

HI Walter (?)

Have you ever had anyone change (or test) the amplifier? I'd think it would be a good place to start. It's pretty much the "brains" for the climate control system.

When you turn the AC on, is there any "drag" on the engine or change in RPM? If you look at the front of the AC compressor, does the clutch at the front of the unit where the belt is start to turn when the AC is switched on?

Have you had the dash pad off or replaced it? There is a sensor under there that reads the cabin temperature. If it's upset it may not know the inside temp, therefore not telling the AC to cut on full blast.

David
EverydayXJ.com

 

there is another Sensing circuit board located in the passenger side blower case. This senses outside air temp.

The electronic parts on that board get covered with grime and they stop 'sensing'. This board can be removed and cleaned but you need to get on your back, inside the footwell, with a bright light and a small tipped phillips screwdriver to reach it.

If the blowers (there are two), are not reaching 4th speed, you need to watch the recirculation flaps to see if they are opening when the a/c is first started.

The recirculation flaps are located at the bottom of each blower case, passenger side, and driver side. Turn engine on, wait 3 minutes, turn TEMP knob to 65, put your hand over the bottom of the black steel case as you switch the SELECTOR knob to AUTO, you should feel the flap opening; It happens very fast, so the hand must be at the bottom of the case before you switch the SELECTOR knob.

If both flaps are opening, the problem is elsewhere.

 

If you bought it over-the-counter at Checker Auto it'll be for R134 refrigerant and the fittings for the gauges will be a different size....unless your Jag has been converted to R134.

Checking the level of refrigerant charge is a good idea. However, it is important to know if the climate control system "understands" the commands being given and whether or not it is following orders, so to speak.

Adding a bit to what Jose mentioned let me ask you this: if it is very hot in the cabin and you set the temperature knob to the coldest setting ("65" as I recall), does the system respond by diverting all air to the center dash vent and going to the highest fan speed?

The answers are "yes", that's good. Low refirgerant level may prevent the output from being as cold as you like but at least you know the system is trying to operate properly.
..."following orders".

If the answer is "no" then you have other problems.....which may include blending hot air from the heater core with cold air from the evaporator core, which is normal unless, of course, full cooling is being asked for.

Cheers
DD

 

another overlooked part when troubleshooting the XJ-6 a/c-heater system is the Expansion Valve. Located behind the cylinder head, connected to the heater core/matrix at the firewall. see picture below.

These valves clog, reducing a/c performance. Replacing it as well as the Dryer/Accumulator is never a bad idea. But that means removing and recovering the old gas, evacuating the system again, and recharging. surely there must be qualified a/c shops in Arizona.

But I think we're just clogging Walter with so much information!

Let me say that I got tired of taking my XJ-6 to different a/c shops. Nobody could fix it. One day I saw an ad for a 12-week Automotive Refrigeration school at a local Technical School. I registered and attended every day, 7:00 to 3:00. Didn't miss a day. 12 weeks.

but I couldn't understand a thing: Low presure side, High pressure side, suction, discharge, liquid state, gas state. I did notice that as the weeks went by, less and less
students showed up for class, until one Thursday nobody showed up but me. And there I was with the instructor in an empty classroom. He asked me, why are you taking this class? "to fix my own car, but I don't understand all this stuff" I told him.

so he said, "We're going to fix that", and he pulled out a a/c 'kit' which we assembled together, a Bench a/c system, part by part, a kit designed for students of automotive refrigeration, run by an electric motor, but otherwise it did everything a car a/c does. He took the time to explain every part and what it does, and why, and when. Everything was mounted on a stand, just like on a real car.

By the end of the day, I had a good understanding of automotive refrigeration. It took a patient instructor, a bunch of no-shows, and a hands on the job approach for me to "get it".

That was 1999. I graduated and went home to rebuild the a/c in my XJ-6. I replaced all the parts that were questionable, including the compressor, all three of us, me, myself, and I did the work using the Factory Service Manual for the detailed Pressures required. The instructor loaned me an EVAC pump and gauges, I recharged with R12, (bless R12), and my a/c is still working today, March 2009. It is a freezer in there. No exageration. 10 years of uninterrupted service.

When these systems work at their peak, they work great. They can be fixed.

 

Wow. Thanks everyone, I have a lot of homework to do. One thing I know is that the other day the temp warmed up a tad it wasnt really cold with the ac on. Later in the day when I drove the car it was a little cooler. I guess my car has not yet been converted. If I have near 100 dollars what should I be able to do?

 

spend them in a night out and forget the a/c. $100. will not buy you much a/c work.

Jose

 

rats.

 

I bought a tested ac amp and put it in.........no heat. I bought an untested servo so I hope that fixes my worries. I need heat, we moved to Colorado and it is cold here. Is the servo tough to replace? the sensor under the dash....is it hard to find and replace?