Jump to content

Air Con Issues

Recommended Posts

Replaced Air con valve but still blowing hot air only regardless of cold/hot settings. Wiring connector is in good clean condition.

Car is 2007 2.7 diesel S Type. 

Any advice please.

Thank you.

Link to comment
Share on other sites

What do you mean by "Replaced Aircon valve" ? Which connector is in good clean condition?

There is  what amounts to an S-Type A/C system troubleshooting bible written by a guy in the states called Claus. I may have left a reference to it somewhere on here, otherwise check out the US Forum. We went through everything about a year ago lasting a couple of weeks. Unfortunately my problem was the Compressor. I hope your problem is simpler.

Link to comment
Share on other sites

Check this out, Following Karls advice. Check kr98664. 



This is quite long and you will find in it links to Karl's excellent guide along with the fault finding that was carried out resulting in the substitution of the A/C compressor this was back in July 2020 and I changed the compressor when it got cooler in the following spring.

If you search on kr98664 (Karls's login you will probably find the guide. There is another one but it is not as complete.

Good luck for a Cool Cat!

Link to comment
Share on other sites


blowing constant hot air is very rarely a aircon issues

its either a faulty dual coolant control valve or climate control module, a bad dual coolant control valve, can also take the climate module out, so both may need replacing at 90% of the times



Link to comment
Share on other sites

The DCCV is the most common, which also can cause the control unit to fail. I changed immediately the DCCV as you you do!! But after testing, the old one worked fine too. Follow the procedure in Karls guide and you won't go far wrong! The system is complicated!  If you are unlucky In the end there are 2 components remaining. One will cost you about a grand to fix and the other one will probably mean you will take the car to a scrappy unless you are a real nutter or live in Alaska.

Anyway after several weeks of tests and exchange of information with Karl. A visit to an A/C specialists with strobe and pressure tests the verdict was a tired compressor. Several indies made half hearted attempts to change the compressor only to call me after a couple of days saying it was too complicated.

I did it myself in about 15 hours (Jaguar say 10), I would not do it again. The manual is wrong and missing valuable information! Now I understand why most Indies refuse this job on the Diesel. The biggest complication on some of the petrol cars is to unbolt an engine mount and raise slightly the engine, a doddle!!

Just like following the advice on batteries / connections etc, For S-Type A/C the Karl guide needs to be followed to the letter! I cannot under estimate the help I gained in ascertaining my problem using this guide.

Hopefully you have a duff DCCV, poor connection or duff thermocouple etc. BTW there is also an OBD2 code which is false regarding an air distribution flap motor which doesn't exist on later models.

Thats about all I remember of A/C  fun  from 2 yrs ago, I am now 73 and would not consider doing this again..................................

Link to comment
Share on other sites

Just one point regarding the DCCV control unit. Normal faults with the DCCV cause tracks to burn out on the control unit PCB and are clearly visible, Photos of this are plentiful. Other faults  with the control module can be difficult to check as it uses a PCM type of system to open and close DCCVs. A voltmeter will not show this. An Oscilloscope or simpler still an LED with a 1K resistor in series can be connected across the individual DCCVs measuring on the connector on the end of the dashboard. Each time it flashes the relevant DCCV has opened and closed, allowing some hot coolant into the internal heat exchanger.

Link to comment
Share on other sites

I think your compressor will be OK, I doubt it has seen a great deal of use in the UK.

My car has been in Madrid, Costa del sol and Costa blanca all its life.

BTW did you find Karl's troubleshooting guide? The system is quite quirky!

As Joe said 90% of the cases are covered by just a few parts. Some of the cheap DCCVs can also be defective new! Follow the guide and you won't go far wrong or waste money.

Good luck


Link to comment
Share on other sites

Pleased to say that Air Con problem now resolved. I had already fitted a new valve, but still had problem. I sent module to ECU Testing of Heanor to repair. I now have it back and things are working perfectly.

My car is touch screen and the module is above the glove box. It is easily removed and re-fitted once the glove box is removed.

Thanks for your previous replies guys


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...