my panel from today, these issues occur regardless of panel settings.

throttle body coolant line replace project. Lot's of work for a $15 part.

radiator fun




SOME HISTORY-
I personally replaced the radiator earlier this year along with the serpentine belt. Prior to that, the AC was blowing hot air out of the driver’s vent and cold out of the passenger vent. DCCV issue

Before Arizona summer showed up, I had a respected auto shop evacuate and refill my AC system since I had opened the system with the radiator replacement. After this, the AC would blow freezing air out of all outlets.

around this time, I replaced the throttle body coolant return hose located under the intake manifold. Great fun at home!

I also replaced the Mass Air Flow sensor, air cleaner, cabin cleaner, the coolant reservoir and the original fuel filter.

I disabled the DCCV coolant lines and return lines temporarily. When the temps get reasonable, not 115, I’ll crawl under and replace the DCCV.

.THEN—

What I’m experiencing now is intermittent cooling. Sometimes when I turn on the engine, Cool air comes out immediately, but will turn to warm air after about 5 minutes only to return to cool again after about 20 minutes.. ( I did clean out the Cabin Air Temperature Sensor at this point)

At other times, It won’t cool regardless of the DCC panel settings. Other times, it will start out warm and then randomly begin to cool.

When I turn the AC on and off, I don’t detect any change in the RPMs. I can’t see the AC clutch to see if it is engaging I don’t see any frost on the evaporator

Today was a good example, start out cool, warm after 5 minutes. Car parked for 1 hour, when I restarted the car, I turned on the A and cool air came out?

Thanks for reading this and I look forward to the always great advice from the forum!

Bob

 

firstly you can remove the main radiator without degassing the air con . you just bend the alloy AC pipe out of the way of the lower coolant hose outlet 10mm .
then bend it back when finished .
also you change the dccv from above not from below .
2 things it might pay to check .
1, check the RCCM behind the glove box is not fried . this can happen when the DCCV goes bad.
2, it may pay to have the AC pressure tested incase there was a leak. it does sound like a low pressure issue .

Nice tidy example of a S-TYPE by the way.

 

I have the car scheduled with a local auto repair to do some diagnosis on Monday. Thanks for the tips on the dccv and the rccm.
Bob

 

By any chance do you use British Automotive in Scottsdale? Greg has taken great care of our Jags over the years and has proven to be honest.

 

Bob,

I'm curious to hear what the shop finds. Hopefully they can do a careful diagnosis and not just make expensive guesses with your money.

The heater core is totally out of the picture, right? You mentioned it had been bypassed but no details of how. I just want to be 100% sure that hot coolant isn't somehow reaching the heater.

You can make huge strides in your troubleshooting with two simple things:

1) Clip an inexpensive pocket thermometer in the center outlet on the dash. Instead of just saying the air feels warm or cold, a specific value will really help. Let's say you've got 100F ambient air and the air from the outlet feels warm. Are you getting 80F air from the vent? That means you've got SOME cooling action, even if not enough. Or do you have 100F air from the vents? That means NO cooling action. Huge difference for the next steps in troubleshooting. Or for anybody else in a similar situation, but with the heater hoses connected as normal, if the dash air is warmer than ambient, that's coming from the heater.

Same with the temperature for those intermittent times when the AC seems to behave itself. Are you seeing a nice, frosty 38F? Or a so-so 50F?

2) Figure out some way to observe the face of the compressor pulley. Maybe one of those small inspection mirrors on a telescoping stick? You really need to know if the compressor clutch is being commanded to engage. Huge difference in how to troubleshoot based on this one observation.

You had mentioned watching for an RPM drop when the compressor clutch engages. I tried this on my '02, but the results may be slightly different for a later model. In Park, there was absolutely no change in RPM. The tach was steady as a rock. I'm assuming (Danger! Danger!) that you also tested while in Park. In Drive, there was the slightest drop, maybe half a needle's width at most. In either case, the PCM is very good at maintaining a steady idle speed, so this isn't really a valid troubleshooting technique.


​​​​​​Next time the AC misbehaves, pull over and park in a shaded spot, somewhere that the pavement isn't too hot. Let the car sit for 30 minutes or so. Do you get a big puddle of water under the car? A little is normal. A lot means the evaporator has iced over. This could mean low refrigerant or a defective evaporator temperature sensor.

Make sure to do all of your troubleshooting in manual LO for now. This bypasses most (but not all) of the automatic control features. It's a great help for troubleshooting.

In case you hadn't seen this guide:

https://www.jaguarforums.com/forum/s...ol-how-185002/


If I had to gamble on something, try the relay that controls the compressor clutch. Swap it with a known-good relay from another system. The fog light circuit is a good donor. Details in the guide linked above.


Keep us posted.

 

And today is Tuesday...

Survey says?