The 2005 purchased on Monday had great air conditioning, just serviced, Forgot to check for heat. Well yesterday it was about 40 degrees out, put the heat on, no heat. The water valve for the heater core was leaking, so replaced it, lot s of heat now. Problem is now the heat keeps coming out, & wont stop, drivers side more than passengers, when the heat is turned down, the air conditioner can not over come the heat. The only way to stop blowing hot air is turn the blower off. What is the most likely issue causing this problem?????Seems like the flap to the heat might not be shutting, so the heat keeps on & the air can not over come it putting out heat all the time.

 

Sounds like you basically answered your own question. No heat, made a change in the system due to a different problem, and now nothin' but heat. Looks your new DCCV is bad from stock.


Close, but no cigar. Unlike most vehicles, there is no flap that controls the heat output by regulating airflow. Instead, all air into the cabin passes through the heater core whether hot or cold is commanded. The big difference is the DCCV regulates the flow of hot coolant through the heater core as needed.

Long-winded troubleshooting guide for you here:

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


Specifically, run the tests in post #2 to check the operation of your new DCCV. Don't change any other parts until you verify that. Maybe you'll get lucky and the problem is as simple as a blown fuse. Without power, the DCCV defaults to full hot for safety to make sure the defroster will work.

The guide also has a link to check the control module for damage sometimes found on 2003+ cars.

 

If you search this forum, you will see this topic has been covered many times:

https://www.jaguarforums.com/forum/s...003-faq-36719/

 

Looks like the dual control valve was what i replaced, it was leaking coolant.Three hoses, one on bottom, two on top, an electrical connector, & a bolt to hold it in place. You think it's a bad part?

 

The DCCV has a very high failure rate. Yours wouldn't be the first one bad out of the box. If not the valve itself, maybe the connector isn't fully seated or one of the contacts pushed back.

Either way, your symptoms changed dramatically for the worse after the replacement. Run the tests in that troubleshooting guide to be sure. For the moment, ignore your previous conditions. Base your troubleshooting on the current symptoms after the replacement.

If it comes down to another DCCV, don't get another from the same vendor. Could be you'd get another one from the same bad batch. I've had that happen with other parts, although not a DCCV. Talk about a troubleshooting nightmare!

 

I've said it once and I'll say it again. Ford Motorcraft DCCV. Don't buy aftermarket. They're cheap for a reason and who the hell would want to swap that part out twice?

 

This was a genuine Jaguar part, list $343 my price $275. Was my thinking, on the part, pain to get to, so do it once. Computer control module? I sure hope not.

 

Who knows, the seals may have swelled if sitting on a shelf for years.

As far as the modules, the typical damage can be repaired. More details at the previous links.

 

You could hope the DCCV is OK and test the other things.

 

Problem appears to be handled, at least for now. Had a burnt spot in the trace as was predicted. Bridged the burnt area only, leaving part of the original trace, at both ends, as a safety factor. A dab of gorilla glue to protect the repair from vibration, put it back together with the desired results.

 

Great news indeed!