Hi, Just purchased a 1999 3.0litre S-Type. It's in really great shape, recently had a rear suspension overhaul and has a full Jaguar Main dealer service history.

But it does have one issue....

No matter what temperature i set the climate control to - It only blows cold air.
I have read posts about issues with the climate control only blowing hot air - but the only time i managed to get hot air was on the drive home with the car, when a gap in the traffic alowed me to use the kick down and accelerate to 80mph - Then the heater started blowing hot (although this soon stopped).

Any ideas?

 

I'd probably start by checking the flow to the heater core and maybe back flushing it to make sure it's not clogged, after that it's the usual suspects, DCCV, CCM, thermostat etc.

 

If you don't know when the thermostat was changed last, I would do that immediately. It needs to be done periodically anyway, and a malfunctioning thermostat could be the cause of no heat.

Also, familiarize yourself with the below site, as they have lots of good info and solutions to climate control problems...
DIY: Diagnose It Yourself - JaguarClimateControl.com

Good luck,
Steve

 

Thanks for the feedback chaps....

Is there a significance (regarding narrowing the problem down) that every time i accelerate hard** the heaters blow hot (irrespective of the temperature setting) for a few minutes - but then go back to blowing cold?

**On 3 occasions have had the opportunity when using a short section of dual carriage way, to accelerate hard (inducing the gearbox to kick down) from 30mph to 80mph for a very short time. Its been on these occasions that i have experienced the heaters blowing hot instead of the normal constantly blowing cold.

 

Yes but the 6 cylinder cars don't have the AUX coolant pump (Or do they?) so I can't say this is your problem.

I have a 2005 STR on the 4.2L engines (SC and NA) the AUX pump is to help circulate coolant when the engine is at idle or low speeds. Since you get heat when you rev the motor that is a sign your AUX pump is not working BUT again I did not think the 6 cylinder cars had this?

Do you know if your car has an AUX coolant pump?
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I also don't think they have the aux pump.

 

I have a 2000 3.0 and I have a little information on my page “illustrations” that might help. I would be looking at flushing the coolant and heater core first. The mixing of non compatible coolant types have been known to gel. Most of the time when the DCCV fails you will get hot air in the cabin; However, I would not rule it out entirely. As for the coolant pump the 3.0 do not use one.

Link JagRepair.com - Jaguar Repair Information Resource

 

i had same problem. the hoses in engine bay were hot as so water was going in and out the heater. Started working this month all by itself . the system uses doors to open to regulate air and heat so mine have decided to work. I still remember the days before CC and simple hot cold controls. I bought new audi last year and got the manual without CC so i control the heat.

 

I am also having climate control problems, just now researching. But I do have a possible answer to why you get heat when accelerating. I had Volvo Speedwagon that did this. The answer was that the car shuts off/bypasses aux systems when the engine needs all the power. I assume most computer controlled cars do this.

 

Only at WOT.