Hello,

Now cooler weather is arriving in Britain we've noticed our heater works for 5 - 10 mins after cold start, then no heat.

There is a small leak in the radiator, would this effect the performance, perhaps an air-trap in the heater core?

Thanks.

 

Radiator leaks can indeed affect a vehicle's heater operation. I'm not saying that is the only potential source of your issue, but it is probably contributing....

 

Is it leaking at the bottom left corner near the DCCV?

 

Hi,

I don't think so I need to remove splash guards. So are there classic symptoms of the DCCV failing - would this effect Aircon also?

Thanks

 

The abilty, or lack of, the system to build up pressure, can sometimes cause heater operation issues.

NOT only in Jaguars.

The V6 has NO auxillary heater water pump, as do the V8 cars, so the water pump, and system pressure, has to get the coolant thru that heater. This can be an issue at times. I have had to help it bleed on both ours when I changed the taps.

Our RHD cars DO NOT have a sepearte heater bleeder, as do the LHD cars, so the system is self bleeding, and does so constantly.

That leak "could" be upsetting the balance.

The heater DCCV is at the RHF corner of the engine bay, and is easy to get out, NOT, HAHA, absolute mongrel. Brilliant design, or someones warped sense of humour.

I strongly suggest replacing the sway bar "D" rubbers at the same time that tap is out, coz the tap has to come out to change the RH bush, and Murphy will have that bush fail 3 weeks after you do the tap, savvy?

Before diving into it, go inside the cabin, locate the dash light dimmer "thingy" on the LH side of the steering column, and near that is the SMALL vent grille for the "in car temp sniffer", and they get full of dust, and the climate unit has a hissy fit, just like you are describing. Clean it out, remove the sensor (from behind) and carefully clean it, and then replace it, you might be lucky.

 

+1 on the comments about leaks and lack of pressure. On my '02, if the coolant level drops, the heater output is erratic, especially at idle. In fact, I've learned cold air at idle means it's time to double check the coolant level and then all would be good for the rest of the season. I never found any leaks (until very recently).

A couple of days ago, the heater quit altogether. The system had lost about a quart, which was far more than previous instances. A coolant top off was no help this time. I finally found a leak in the big Y fitting in the upper radiator hose. No puddles on the ground, just an occasion whiff of the stuff. Due to the location right behind the fan, I think any spillage was evaporating quickly. The leak was enough to keep the system from reaching normal operating pressure, however, and this affected the heater output.

The new hose arrived yesterday and will be installed this evening after work. I'm pretty sure this will take care of the no-heat condition. No guarantees your situation is the same, but I'd highly recommend fixing the leak before any other troubleshooting. These heaters are sure sensitive to coolant pressure and level. I'd hate to see you chasing your tail trying to "fix" other problems that may not exist.

 

Any new word? It's been a week since I fixed the leak on my '02. After that, all I did was top off the coolant and everything has been groovy with the heater. I just wanted to pass along the info and hope you find it helpful.

 

Hi. I am only getting hot air and i mean hot.
At 19c i feel as tho im in a volcano.
Think i may need to replace the whole unit!

 

Hello all,

Thanks for your comments.

Well the good news is that after replacing radiator, we had Aircon serviced and recharged - now like an arctic blast. The bad news - still exactly no heat.

We just noticed Norri asked earlier if the leak was near DCCV - there seemed to be a lot of coolant spray in that area which I presume was created by the fan operation?

Thanks

 

Despair not! Even though the situation may now seem worse, it's actually better from a troubleshooting perspective. Instead of chasing an intermittent fault, you've got a hard fault staring you in the face. I'm a professional mechanic and personally MUCH prefer the latter.

Make sure the coolant level is correct. It may have settled after the recent work, so check that right away.

Do you have access to a coolant pressure tester? I'd suggest making sure the system will properly hold pressure, as the heater system seems to be very susceptible to problems due to low pressure.

Also, make sure the system has been bled properly. Even if the shop swears it was done by the book, it couldn't hurt to try it again. I'm lazy and have NOT done this on my US spec car and it's been fine, but I think the UK versions are much more persnickety about bleeding.

Then I'd see if the associated hoses are actually getting warm. Check the lines feeding the DCCV valves, and the lines from the valve to the heater core. This should give you an idea if/where the hot coolant is being routed. You could have a fault such as hot coolant not reaching the DCCV in the first place. Or the valve is stuck closed. Or the valve is fine but not getting the proper signal to open. Lots of possibilities, so feel for heat in the lines to know how best to proceed.

 

Ok excellent thanks I will take note of your comments.

This weekend I will perform an electrical test on the DCCV.

Which fuses should we check and voltages on the Pins? A quick bit of research points me to pins FC-27 but no fuse numbers.

Regards,

 

Fuse #1 in the engine bay compartment.

Pull the plug from the tap, the centre pin has 12v ALL the time the battery is connected.

Both our X200 cars had fuse #1 blown, and the taps on both cars were toast. New taps, new fuses, sweet as.

 

Thanks Karl,

Bit of a strange one going on here.

So drove the car home last night (topped the resevoir in morning), heater setting "Hi" - nothing but cold air. After about 30 mins I dropped the setting to 24c and lowered my window 1 inch - air began to warm-up nicely. Warm air continued 20mins and as i approached my house i dropped temp to "Lo" and vents cooled.

Pipes under hood felt red-hot - I wonder if dccv is getting stuck slightly open? Can it be tested somehow to show displacements?

Regards,

 

Sounds like you are making some progress. The system is capable of supplying heat. Now if we could just get it to do so on a reliable basis...

By using the HI and LO settings, you have basically eliminated the automatic portion of the climate control system. So I highly doubt you've got a bad temp sensor in the cabin, etc.

You mentioned the pipes feeling "red hot". You mean the 3 metal coolant lines on the inner fender on the right (when facing forward) side? Does your DCCV have 5 lines? If so, the 3 on the aft side are connected to the heater core. The top line feeds the left (once again, when facing forward) side, or US driver's side. The middle line feeds the right side, or the UK driver's side. The bottom line is slightly larger and is the common return from the two portions of the heater core.

I do wonder if I gave you some bad advice when I suggested checking the temperature of these lines. Was the system putting out heat when you said the lines were hot? If so, that's good. If no heat at the time, but the lines were still hot, that would suggest lots of radiant heat from the nearby exhaust manifold, skewing the test results.

If the heater system is working properly, and the system is set to HI, both the top and middle lines should be quite warm, indicating they are moving lots of hot coolant. Here's the important part: The lower line (coolant return) should feel a little cooler than the two supply lines. How much of a temp difference? I don't really know. But if heat is being properly transferred into the cabin line, the return line should be cooler than the two supply lines, at least to some extent.

As far as testing the DCCV itself, I'm not sure how much can be done. Per a factory training manual I have, the DCCV is fed a constant 12V supply, and the plungers are controlled by separate variable pulse width ground signals from the controller. In other words, I don't think you can just jumper power and ground to the valve to make it operate. Perhaps somebody with more DCCV experience can jump in here.

I did notice one thing you can do. Per the manual, "Battery voltage (12 v minimum) is required to close the valves so that if electrical circuit failure occurs, the valves will remain open and allow full coolant flow to the heater core."

The way I read that, if you disconnect the connector from the DCCV, the internals of the valve are spring loaded to open and send hot coolant to both sides of the heater core. If you can duplicate the no-heat condition again and then disconnect the plug, you should get heat. If not, the DCCV has stuck closed and needs to be replaced.

 

See if this information helps.

Link. http://www.jagrepair.com/DCCVSType.htm

Gus
www.jagrepair.com

 

Lots of great info at that link.

Looking at your post-mortem of the old valve, is it possible to replace just the guts without removing the entire assembly from the vehicle? I know access is pretty tight, but it might be better than dealing with all those hoses and the mounting bolts.

Awaiting enlightenment.

 

No. Just change the DCCV and remove one more trouble prone componet from your problem.
.
.
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Yes that could be possible.

I would first fix the leak then I would burp the cooling system and add coolent as needed. That sould fix the problem.

 

OK guys just to update you all,
Thanks for all your comments by the way.

We took Jag recently on 150 mile trip in awful british november weather - cold, windy and wet.

The usual puff of warm air for 10 mins then nothing for the entire journey there, and back home. Freezing freezing freezing. A/C was off by the way.

After 50 miles into journey we popped the bonnet - the alloy pipes to and from dccv were all very hot - especially the return pipe which was painful when touched.

What is going on here?
The dccv is clearly 100% opening - could it be a temp sensor? A blend motor?

Thanks guys,

 

"The" return pipe? Isn't yours a 5-pipe DCCV?