The posts do tend to say what cured the problems. Just put a bit more effort into reading

 

I haven't solved mine yet (replaced the DCCV because it was leaking anyway), but if you start from the least expensive, the list of things to check might go like this:

- frayed wiring going to the DCCV (no parts, just effort to track down)
- internal (i.e. driver & passenger compartments) temp sensors (~$25 for each part)
- DCCV (parts about $200-250)
- Air cond. module ($800+ for new parts... cheaper if you can find a good used one)

Good luck... report back with your progress!

 

Boy I am glad I don't have that climate control/hot air issue...as I wouldn't like to sh*t twinkies either!!!! Thats a good one, thanks for the laugh!!!!!!

 

I had the same fuse blown and replaced. An hour into my drive the hot air started belching through the cabin. Must have a short of some kind to be blowing the fuse so quickly?
Any suggestions where to find a wiring diagram for a 2005 S type with 4.2L to track it down??

 

It's near enough the same as the ones in JTIS - plenty of threads on here to get you to a copy but ebay is easy and cheap.

 

the fuse for the DCCV power is the same one for the ac clutch. if its blown its useally from coolant getting into the solenoids of the DCCV and causing a short to ground. You may still need a DCCV and you may also end up blowing the ground circtuits in the AC ecu that close and open the DCCV solenoids, they always have power through that fuse and the ac ecu provides the grounds. Leaks from the DCCV and/or the coolant reservoir are the useall suspects/causes of blown ac ecu's. And yes you can have the boards repaired, others have done it here.

 

Bob,

Back in Jan I had the DCCV valve and the AC Module replaced under warranty on my 2005 S-Type. Apparently the DCCV problem caused some circuits in the AC module to fry. Then in March the condenser sprung a leak which was again fixed under warranty. Thank God for the warranty and that it was cold enough I didn't really need the A/C at the time.

Mike

 

Mike,

What's your current mileage? Unfortunately, you've experienced some issues recently that I wouldn't have expected in your particular car. As you said, three cheers for your Select Edition warranty. How much longer does it cover you (I assume your time will run out before your mileage does), and have you decided whether you will keep the car once your Select Edition expires?

 

Hi Jon,

I have around 61K miles on my Jag currently. The warranty is good until 31 Jan 2011. I still plan on keeping the car though. I couldn't get anything else nearly as nice for the price and it is a lot of fun to drive.

Mike

 

Just be sure to ride that warranty like a racehorse during your last couple months of coverage. That's what I did with the factory warranty and it really paid off....

 

Hi Jon,

Definitely plan on it. The upside is that I basically have a new HVAC system now so it should last for a good while. The timing was good in that it happened in the winter when I didn't really need it. Mine seems to be a typical Jaguar in that some of the ancillaries have problems but the basic running gear is pretty stout.

Mike

 

BRUTAL's post (post #8) about how the system functions and what may be wrong is spot on.

It's best to diagnose and narrow down the source(s) of this type of problem before we start to replace parts blindly.

Follow this procedure to diagnose this problem (the only tool you will need is a multimeter):

1. Run the engine.

2. Set the controls to max "Lo" for both driver and passenger sides.

3. Confirm that the air is still blowing hot (take note which vents blow).

4. Disconnect the plug from the coolant control valve and take voltage measurements at all 3 contacts in the plug. The middle contact should read 14v or so.

5. Take resistance measurements at the 2 outer contacts in the plug (measure between each contact and a chassis ground). The 2 outer contacts should read close to 0 ohms.

6. Jumper the middle contact in the plug to the middle contact at the valve. Jumper one outer contact in the plug to the corresponding outer contact at the valve using the multimeter to measure current. Be careful that you don't short anything with the middle contact in the plug (it's always hot +12v-14v). Repeat the measurement at the other outer contact after disconnecting the first outer contact (don't disconnect the middle contacts yet). Each measurement should read 0.6 to 1.1amps.

7. With the middle contacts still jumpered between the plug and valve, jumper an outer contact on the valve to a chassis ground, while using the multimeter to measure current. Check to see if any vents blow cooler air during this grounding process. Repeat the measurement at the other outer contact and check the vents again.

8. Reconnect the plug to the valve.

9. Shut off the engine.

10. Report the results.

 

I love how easy it sounds - but I have to take have the topend of the engine off just to get to the connection. If I find that the RH contact is not grounding where should I look next (mine has NAV)

 

the easlier way is to go to the plug on the left side of the dash and monitor the ecu ground signals as you scroll though cold to hot temp settings. You can watch ground come on or go to batt voltage when inop(opened valve) this does only check the ecu function. it doesnt verify that the valves themselves are stuck either open or closed. A inferred temp gun is good for this on the discharge heater pipes. And never ever let leaks at the valve go, theyre the #1 reason for shorting out the ac control module

 

Thanks Brutal! My 2005 STR had the DCCV just starting to weep anti-freeze. I changed it as soon as I saw it because of the information on this list. I also knew to look for it and found it after only a small stain on the bottom pan cover.
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When I took everything apart to check the DCCV I noticed a little orange staining, but no actual fluid. So I decided to go ahead and replace the valve. After the install I still have same issue. Brutal, where exactly is this plug? In the cabin or engin bay?

 

The left side of the dash behind that side access panel. Its a green 14 way connector and the 2 wires are brown/white, and brown/green in slot 9 and 10

 

Yes, it's difficult to get to the heater valve, especially when trying to take electrical measurements. I did the following to help myself with this task:
- Unbolt the water expansion tank and set it aside (without disconnecting any of its hoses).
- Use a long (around 12"?) extension with socket to get to the heater valve's bolt.
- Loosen the heater valve's bolt so it can be rotated, then rotate it just to get better access to the connectors.
- Attach alligator clip leads/wires to the contacts in the heater valve connector.
- Insert wires (insulated but stripped at the ends) at the heater valve mating connector (harness side), then attach alligator clip leads to the wires.
- Use the alligator clip leads as extensions to the multimeter.
- Make sure to temporarily tape up any exposed clip/wire connection to prevent short circuit.

If you perform this step:
5. Take resistance measurements at the 2 outer contacts in the plug (measure between each contact and a chassis ground). The 2 outer contacts should read close to 0 ohms.

..and find that the RH contact is not grounding when the AC is set to Lo, plus made sure that the heater valve functions OK when you manually ground the valve's outer contacts, then there is a good chance (about 80%) that climate control module (the vhs tape-sized rectangular black box hidden behind the glove box for nav-equipped cars) has already been fried by your previous DCCV.

So, you can either have the module replaced for a lot of money, only to have it fry again a few years down the line when that heater valve shorts again, or you can have the module professionally repaired and upgraded with built-in fault protection so the module never fries again.