96 Vanden Plas, heater blows cold air
 

Greetings all,
I am hoping to get some tech help here so here goes.
My mom's got a 1996 Vanden Plas with the straight 6. The heater blows in all the different settings but blows cold air. I thought that it may be the thermostat because the lower radiator hose stays cool after 20 minutes or so sitting and running, but the weird thing is that the temperature gauge needle never even gets all the way up to the "N" which I assume is the "normal" operating temperature range. If it was the stat, shouldn't it be overheating? Both electric fans run constantly at startup and I haven't noticed them kicking on and off but could that really keep the temperature that low?
This is the first time I have ever worked on one of these and I am not exactly sure whether it could be a bad or clogged heater core, stuck thermostat, dirty radiator or some combination of all of the above.
I figured I should flush the entire system and put in new coolant but I don't exactly know where to start. :icon_dunce:
Also, I'll be darned if I can find a repair manual for this thing.
If I have to get behind the dash or something I would want to disable air bags and such, plus, just knowing where everything is located would be a good start!
Any help you all may have would be greatly appreciated as its a bit chilly here in this part of Oregon this time of year!
Thanks!

Replace the thermostat and report back. Easy job, common problem. There are other possibilities but first let's get the engine up to normal temps.

Manuals (CD/DVD) are available from:

Jaguar Heritage

Some of the Jag specialists probably have the CD manuals in stock, or try Ebay. Watch for bootleg copies, if that sort of thing bothers you


Cheers
DD

My 1993 xj6 had a stuck vacumm switch. I assume the later models used the same set up. Its located just below the wiper motor. A pain to get to but if not the thermostst then check that.

MOST OF THE TIME
Jaguar V8 thermostats stick CLOSED and AJ6/AJ16 thermostats stick OPEN.

bob gauff

The X-300 forum FAQ sticky has a link to a copy of the Heritage Manual. It is in the first post, about 3/4 of the way down and has the following description

"X300 Service Manuals 95, 96, 97 ( Includes AJ16 manual...."

I am not sure about the ethics of downloading a pirated copy rather than paying someone else for a pirated copy. I bought mine from Heritage, so I can feel good about myself on this one!

Okay, new stat installed, flushed the cooling system, new coolant. Good operating temperature but still no heat.

Well, from what I have been able to find out thanks to all of you on here, there is a 'heater valve' and a electric water pump that circulates the hot water through the heater core. Both items are way spendy SOB's. :icon_omg:
I found these two on Jagbits.com:
Heater valve: Code MNA6711AC $375.44
Electric water pump: Code MNA6710AB $499.12

I assume that one of these is what you were referring to in your post...is there a good way to test these parts? Maybe one or the other is just dirty or stuck?
I do have a hot hose up to one side of the heater valve, but the top of the little canister and the other hoses are still cold, so I'm thinking that may be the culprit..?
So, do I yard these things out and try to bench test and clean them? Can I disassemble and rebuild them?
Yikes, these things are expensive so if I can avoid buying them....

Say, Knucklebuster? Is your Mom's name Irene...
 

by any chance?

Nope JonnyO, not Irene.
Irene have the same problem with her car?

Yes she does.
 

I figure it's a sticking heater valve but can't say for sure without seeing the car.

did we ever figureo ut what this was? I have a very similar problem...

Heater control valve
 

Part# MNA6711AC

Book time is a bit shy of two hours.
Check your aux water pump while you're in there.
If it's leaking now would be the time to do it.:icon_party:

And I can get the parts for..
 

[quote=JonnyO;469819]Part# MNA6711AC-$420
MNA 6710AB -$300
Book time is a bit shy of two hours.

No heat cold air
 

I have the same problem and it is the same fix. replaced the thermostat to get the temp back up to operating temperature and still blowing cold air. The heater control valve sticks and intermittently fails and the auxiliary water pump failed. They are being replaced and the parts are expensive. 375 for the valve and 450 for the pump.

I might be time to think about working on the car yourself!

The issue with the pump will (almost certainly) simply be that the bushes have worn out. If you can drive a soldering iron, you can fix it. You wouldn't replace an engine because it needed new spark plugs!

Another issue that's worth mentioning here (for other readers) is that the heater matrix can get blocked up. Luckily they seem to often respond well to flushing (put a hose pipe on it!) rather than needing to be replaced.

Hell yeah - I've said it before, but I really don't think these cars (at this stage in their life) make much sense if you don't want to get your hands dirty...

This problem of no heat while relatively easy to fix, especially the thermostat, top hose and heater valve, would have been beyond my diagnostic capabilities. This is one of those jobs that is mostly parts expense and not labor. The heater valve was intermittent and i doubt i would have found the auxiliary pump on my own. I have no problem with tune up stuff and valve cover gaskets, but my current cars are not as tolerant as my old american cars were of backyard mechanic mistakes

That's what you need to come on here for! Plenty of experts (I'm not one of them!) with a wealth of knowledge to share...

This is a common problem area. The pump can normally be fixed fairy easily. The pump impeller is not connected to the motor by a shaft rather it is magnetically coupled. This means that if the impeller gets clogged the motor can still operate without burning out. You should be able to feel the motor running by touching the housing.

If the impeller is clogged, it is a simple affair to open up the pump and clean the impeller.

If the motor does not operate it is most commonly because of worn brushes. Again these are relatively simple to change and suitable brushes can be found in model shops. You need brushes that are 4mm x 4mm x 8mm long. You can file down larger ones, brush type is not critical.

Probably the most common issue with the heater is the core gets clogged. you can try to back flush the core by hooking up a garden hose to the inlet pipe in the engine bay (run a hose from the outlet side to a bucket) This sometimes works but if no water comes out you will probably have to remove and replace the core which is a bit of a bugger on LHD cars.

You should also be able to feel the solenoid operating in the valve by touching the top of the housing.