It’s been determined that my heater control valve is stuck in the closed position, which is the cause of ZERO heat in the car. I’ve read nearly every thread relating to heat problems on our X100’s, and have not seen any posts discussing the following options...

2 questions...

1. Since the closed valve is the problem, it would indicate a failed solenoid, or a gunk buildup preventing the proper movement of the valve (less likely). The stem of the valve is connected to the solenoid. The removal of the entire heater valve is clearly a giant PITA. So, can I not just remove the 4 screws that hold the solenoid to the top of the valve, remove the solenoid and it’s attached stem/plunger, and replace with that part from a working valve? I’ve seen diagrams, however, that show that the solenoid and the stem might not be so easily removed due to constricted passages within the body of the valve. See link below.

2. Is there a way to bypass the valve entirely, at least for the winter? Seems that a direct connect from the aux pump to the heater core feed hose, and similarly for the return hose should be possible. However, re-routing those hoses would get me part of the way to removing the entire valve anyway, so...

Link for valve side section image. Pg. 70 of the pdf, or 2.4.4 page folio.

http://www.jagrepair.com/images/Trai...des/703_SG.pdf

Thanks in advance for any advice/input.

Windwhipped

 

How can you be sure it is the valve? It is a bit hard to diagnose. Have you confirmed the pump is running for sure (much easier to test, but does not prove flow as the impeller is on a magnetic coupling)? Have you tried a (much easier) core flush? There is a great write-up on this valve in another section of this forum with some detail, but no immediate repair instructions. This is a pricy part, too. The point is to really firm up the diagnostic. This valve defaults open, so there is that (i.e. it is supposed to remain open when unplugged). FWIW, I did drive with it unplugged, and a LOT of heat comes in the cabin. You can use a laser thermometer for clues, but it is harder to get to a diagnostic than it seems. My advice is to start with a cheap core flush and go from there. I know this flush has cured a no-heat condition twice in my own car (and I am not entirely sure why).

Best of luck, keep us posted.

 

Fmertz, thanks for your reply.

The pump is functional. I did unplug the valve, knowing that it defaults open. No heat. As you say, the diagnostics for this entire system are really tricky. I did note that the heater core feeder hose gets hot (going into the firewall), indicative of hot coolant getting at least that far. But the return hose stayed at ambient temp, not even remotely warm. I’ll follow your suggestion re: the flush as the simpler, lesser expensive task. I was confused with the closed valve diagnosis (from a knowledgeable local indy Jag tech), because it seemed to me that no hot fluid should get to the heater core at all. Scratching my head...

 

Other thing I forgot: the return hose from the heater core has a sort of flat kink in it, supposedly by design. It gets some of the blame for these no-heat issues as it is easy to think the kink restricts the flow, but it is hard to be sure it is a true problem. Fairly easy/cheap to replace, though. Kink is due to that non-return valve, more than likely an afterthought due to experimental data. My understanding is that this non-return valve is there to prevent hot water from going back in the core after the engine is shut off and the water gets heated up by the nearby hot converter. I suppose it could be taken out entirely, or even re-installed in the supply hose instead as there is more hose length to work with.

 

Background and details are often relevant. Not just Model and Year which I've added to your forum Signature but, in this instance, how you use the climate system:

1. run with AC on all the time or only when a particular temperature required
2. cycle the AC through COLD to HOT and back occasionally to prevent the air direction flaps and valves sticking

I wouldn't reject the valve as a possible cause but I would check other components first:




Throwing parts at Jaguar soon gets very expensive, especially if it's the wrong parts

Graham