Scratching my head here. I'm not seeing a problem at all. Your four readings track very closely to what I had.

The first test was the compressor and DCCV off, and read 0.0 amps as expected.

Next was energizing the compressor clutch only, and that measured around 3.4 amps for both of us.

Next was energizing the DCCV only (both sides), and that measured 1.4 amps.

Last was energizing the DCCV and the compressor at the same time, and we both saw 4.8 amps. Also note how the amp draw from steps 2 and 3 added together equal #4.

So I'm not seeing any problems. Did I miss something?

Please note the limitations of these tests. These can not confirm all of these components are 100% good. For example, the DCCV could be internally clogged and the amp draw would be unchanged. The friction surface of the compressor clutch could be totally worn away or glazed over, and the amp draw would still be the same All we're doing is making sure nothing is considered glaringly bad at this point.

Still waiting for the results of the paint mark test...

Anybody else got any ideas?

 

Hello abonano

Just thought I would post a quick update on your suggestion for finding out a more exact temperature instead of relying on the dash temperature gauge.

I have acquired an obd2 code reader and it has the live data function. So with the engine at operating temperature, the code reader recorded 204 degrees, which is within your suggestion of being under 210 degrees.

I was hoping the code reader would give some insight into my cooling issues, but no luck. But it did quickly give three "manufacturers specific codes" and referred me to the Jaguar manual. I have not been able to decipher the codes any further. I think I needed a more expensive code reader.

If anyone has any ideas, or further information, the codes are:

P1013, U1035, B1035, and C1035

I don't know if the codes have anything to do with the climate control system, but the code reader's red caution light came on, with lots of beeping.

In the meantime, Forward March with my cooling issues.

 

Hello Karl,

What I noticed between your numbers for the Compressor Clutch, AC and the DCCV all on together and my test is the number of digits in the results and the presence of a zero in my number. Maybe I'm overthinking the results, which is entirely likely, but your results were:

Compressor on, DCCV on: Panel set to LO, AC switch ON 4.8 amps, 35 mv

And my number was 04.82.

But all my other results were three digits after the decimal, such as 3.443 and 1.485.

So I took the presence of a "0" as being half of a value, or half of 1.82. Do you recall having a zero in the results on your ammeter display?

But I do value your opinion on this and move on to the other test of the compressor clutch mark and I'm also curious as to how much voltage is at the DCCV when commanded to be closed. Will tackle getting the wiring harness off the valve next.

Thanks for your help.

 

Please let me know how to get in touch with your 5th grade math teacher. She will want to have words with you. 4.8 and 04.82 are virtually the same thing, a difference of only 2/100ths of an amp. Put another way, that's less than half of one percent difference.

The meter I'm using has a lower resolution than yours. It only shows one digit to the right of the decimal. Yours shows two.

These tests passed with flying colors. Time for the paint mark test. Don't make me fly out there...

 

Can you erase all the codes and see if they come back?
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Hello, good idea on erasing the codes. I'll try that the next time I hoop up the code reader. This code reader is new to me and I'm still figuring out how this thing works.

 

Hello Karl,

Well, the paint mark test on the compressor clutch and pulley is done and everything worked as it should. The clutch clamped tightly on the compressor pulley as soon as I attached the jumper wire on Relay #8, sockets 3 and 5. Started the car for around five(5) seconds and check the results.

As the photos below show, no slippage at all. I even had to briefly restart the engine a few times to get the marks back in view for the after results.



This shows the paint marks before running the engine for around 5 seconds.

Shows the marks still stationery after running the engine for around 5 seconds.


The AC performed better today, actually around 40-45 degrees on city streets. I believe swapping the clutch relay with the fog relay made a difference, as I discovered arcing inside the cover and on the contacts on the original clutch relay. I think I will get a new AC Clutch Relay soon and put the Fog Lamp back in its original location.

But also, the external temperature was lower today at around 77 degrees after a thunderstorm moved through the area. So that might explain the 40-45 degrees cabin temperature, which was a welcome relief. Is there a test for the external temperature sensor in the front bumper. Maybe an Ohms rating or amps spec. I would like to also know that it's working properly.


Thanks for your help.

 

Great news on the paint mark test. See how simple that was? I like to recommend that test because it covers most of the clutch control circuit. It doesn't test the relay itself, so for that I've recommended swapping in a known-good one. Good idea to just replace it, as it's entirely possible the donor was not so good, either.

Don't get sidetracked worrying about the exterior temperature sensor. In manual LO, this sensor is mostly bypassed. It does inhibit the compressor below 27F, but since the AC works normally under most conditions, it's not erroneously sending a signal below 27F only at idle. If still not convinced, there's no need to even measure the sensor resistance. Simply set the control panel to show exterior temperature and make sure the display matches the weather report within a few degrees.

 

Hello Karl,

I think I'm coming to the wire on my troubleshooting. This will be the most "tested" Jaguar around.

Maybe I'll get around to taking a look at the cabin air filter this evening, as I can't remember when it was last changed, but it's been a while.

Then I need to purchase a set of gauges to check the low and high side pressures. If I'm feeling confident enough, I'll do the compressor piston modification, an evacuation and recharge to the proper level of refrigerant and call it a day.

In a few months, the weather will start to cool down for the fall and hopefully I'll have it figured out by next summer.

Thanks for all your help and I'll keep the forum updated with my findings.