I have no heat on my 2005 4.2 S type Sport. We replaced the thermostat and still no heat. The AC works fine. The hoses going through the fire wall to the heater core are cold even when the car is warm. I have done some research and found that the heater control valve aka DCCV could be the problem. Could the DCCV be the problem?

 

It's going to be the valve or the control module or both, you should also try flushing the heater core to make sure it is clear.

 

There is a lot of information about the DCCV and the Climate Control Module (RCM) on this forum.

The DCCV seizes in an "off or "on" postion, or partially does, and hence some have trouble with heat some with cold. Also (as in my case) one side will seize leaving one side of the car hot and the other side cool.

If the DCCV has been faulty for any length of time then it burns out the RCM.

Another area worth mentioning is the wiring harness can rub and cause a problem. This, I believe goes under the front bumper. So it is worth searching on the forum for this as well.

The links below should help. The first one is by Gus, a forum member, and this is for my earlier model and deals with the DCCV. But it is very useful for the information and photos (there are other posts for your model as well just search DCCV but this is a practical and well set out example.

JagRepair.com - Jaguar Repair Information Resource

This last link has good information on the RCM with photos of your model and an inexpensive repair of an RCM board with a burned trace. The RCM can be taken out and sent away for testing if a burn trace is not showing and it still fails.

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


The process for me was:
1. replace the DCCV (good time to change the coolant)
2. take out and check ther RCM for burning
3. send it away for test and repair

Step 4 for me would have been to check the wiring harness for rubbing.

I also should mention the climate control module is situated differently on cars with sat nav. But this is also covered on the forum.

I hope this helps.

 

All of the vents are blowing cold air. Not just one side. No heat at all. I ordered a DCCV, so it should get here this week.

 

Did you check the associated fuses for the DCCV? Also, did you install the thermostat correctly in the housing and bleed the cooling system of purged air?

Start car - turn on heat to "high" and open the bleeder screw on top of the expansion tank to ensure all air has been purged...

You should have a stream of fluid coming out and be sure not to over tighten the bleeder screw (very easy to do)

 

If both sides are the same then it makes it less likely but not impossible for both sides of the DCCV to seize closed.

You might be able to test this by warming up the car and checking the heater hoses coming from the DCCV to see if they are heating up. If they were open then hot water should flow through them to the heater. I suppose you would need to make allowance for surrounding engine heat. From this, if they are allowing hot water to flow then the DCCV may not be the problem.

On my model there are two heater hoses going up to the firewall and into the heater from the DCCV. But there are three hoses at the firewall.

 

All S Types have the same setup.

You have a dual climate control system so you have a split heater core. Two hoses in but only one combined hose coming out.
.
.
.

 

@abonano, I was not aware of the fuses associated with the DCCV. We did purge the cooling system.

 

My DCCV failed with all cold. Happened on a trip, through the Rockies, -31 C, the wife was non too happy.

 

If you are asking where the DCCV fuse is. This is from the link below


"2. Check the fuse for the Heater Valve. It is Fuse 32 (10 amps) in the Front Power Distribution Fuse Box, located in the engine compartment. This fuse is hot +12 volts at all times, and also feeds the Auxiliary Coolant Pump Relay (4.0L models) and A/C Clutch Relay."

"5. Disconnect the plug from the Heater Valve and take voltage measurements at only the inner contact in the plug (harness side). It should read 14v or so (during engine operation), since this connection goes straight to Fuse 32 (10A) in the Front Power Distribution Fuse Box."


DIY: Diagnose It Yourself - JaguarClimateControl.com

 

UPDATE- Replaced the DCCV and Replaced with CCM with a working model. Fixed and no problems for months…...

New Issue- Fuse 32 keeps blowing and I have no AC. Any ideas on why fuse 32 keeps blowing?

 

Measure ohms, follow wiring - may be shorted/chafed.

 

Garden hose, flush both ways several times.

 

2007 S-Type R thermostat. When I replaced mine I installed it incorrectly and this caused me to go to the trouble of replacing a fully functioning Dual Climate Control Valve (DCCV) and the Auxiliary Coolant Pump. With new DCCV and Aux Pump not solving the problem back to the thermostat to find that the three-part thermostat I installed the small spring on the wrong side of the thermostat. Installed thermostat correctly and then heater worked as it should.

 

Problem posted is a fuse blowing.

 

@Ragnor, I replaced the thermostat last year.

 

I found an old link to a similar problem. It might be useful to read.

https://www.jaguarforums.com/forum/s...l-blows-93360/

and this one you may have already seen. Procedure A down the page talks about the DCCV/CCM procedure and fuse 32

DIY: Diagnose It Yourself - JaguarClimateControl.com

If you already looked at these then disregard them but I hope it helps.