1999 S Type 3.0

Having an issue with the interior heating.

Fans blow cold even on max setting until such a time as the car is fully warm and the thermostat opens. Then I get controlable heat and cooling.

From what I have read this is not indicative of dccv issues where the heat is either hot or cold, irrespective of the hvac settings and sometimes side dependent?

I removed fuse #1 and this makes no apparent difference to the output heat - ie when car is warm and the heating is set to cold, hot air is not forthcoming when removed.

I suppose what I am asking is if anyone can confirm if this is infact a by product of a stuck dccv? - Or not.

 

Was the engine at idle when you tried this? The V6 (no aux coolant pump) is especially fickle about heater output at idle, especially if the coolant level is a little low. On my '02 V6, if I've let the coolant level drop, the heater output is marginal at idle. That's always my first clue to check the coolant.

Topping off the coolant helps, but it still takes a couple of drive cycles to work out all the air. I'm too lazy to do the proper bleed procedure. Normal driving (with an additional top off as needed) has always worked for me. Until then, I'd have normal heat above idle, but less heat at low RPM.

Also, try switching off the AC and repeat your test. If the heater output is marginal for any reason, cold from the AC may be giving a misleading indication of no heat at all. To turn off the AC, press the AC button once and make sure the light at the switch goes out.

 

Doesn't sound like DCCV.

What happens if the system is put in AUTO mode and the fan is allowed to do what it likes instead of blowing cold air till the engine is warm?

 

Thanks, both

I will check the level, thanks.

With or without makes no difference.

It is the same, auto or as directed.

I am interested in whether or not the water is directed through the heater core seperately, after the thermostat has opened. How this happens and how it is operated/regulated.

 

The fan should not be blowing at all until there is warm coolant available.

 

I agree with Mike.

Both mine were just plain fickle, and new DCCV on each fixed it.

The RHD cars are self bleeding, as compared to the LHD cars. It still requires the coolant to be at, or a tad above the correct level, and a few drive cycles with daily coolant level checking until it settles.

However

They both produce heat within a few short minutes of starting the engine, and even before the Temp gauge even moves.

I would be checking your pressure cap, and thermostat, age will be against both items now without a doubt. If it were mine, those 2 items would be replaced without question.

 

mmm.....

I will have to check......My memory says it is not, but my memory is also telling me my memory is not very good!

 

Excellent advice, especially about the cap. If the cap is venting pressure early, you wouldn't necessarily see any coolant leakage there because it's at the high point. It would be mostly air escaping. If the system pressure is low, coolant flow gets funky and heater performance drops.

 

Both my X200's, and Tony's (next door) have the cabin fan activate as soon as the engine starts and the instrument "check" lights go out.

Maybe the X202 changed that to the same as the older Series cars, and the XJS. All of those models I had were OFF until the heater pipe pad sensor got tripped with coolant heat, until I by-passed them all.

My X300 also had the cabin fan active at Ignition ON, and the R now is the same.

 

Ah- I see the OP has a 1999, must have been a change with a the first facelift as you suggest.

Living in Canada, getting blast of -30C air in February would not be fun

 

HA - Told you about my memory....

Went out to the car and sure enough the expansion tank was empty. Filled it up and looked for the (non existant) bleed valve by the header. Fiddled with the one on the top hose but dessisted having read some horror stories.

Ran the engine at 1500 rev for a few mins and got some heat when the thermostat opened. Initially the pipes into the matrix were clearly empty so I squeezed some air out of them. Tested an hour later and still getting warm air so (hopefully) most of the air has gone. The pipework is certainly firmer prior to the thermostat opening.

Tomorrow morning will be the telling moment. I will certainly swap the header tank cap as there is no sign of missing coolant under the car or in the footwells.

Thanks for all your help.

 

Waiting with bated breath...

 

Update - Yes

Having topped up and replaced the cap with a new one I still had a loss of coolant. Nothing underneath and no smell at back end.

This morning I took the car to my friends rolling road as the auto will not rev above 2500 revs in Park.

Stood at the front (not recomended) while he hit 5000 revs and noticed a small trickle from the top hose to the waterpump.

I will replace this and update the thread.

 

Good, but let's stick to talking about your S-Type.




This isn't an audition for the Darwin Awards. I'd highly suggest using a cooling system pressure tester. I'm talking about the hand pump with gauge that connects in place of the cooling system cap. I've got this one with an inflatable bladder for a universal fit and it works fine, but am thinking of finding one with vehicle-specific adapters:





Some auto parts stores offer free "rentals", too.