swetnK: If the shop finds a coolant leak, it will likely be in one of three common locations:

1) The coolant reservoir: The nipples sometimes crack, and stress cracks can form in the flat bottom of the reservoir, which leak little to nothing when the engine is cool, but leak more when the coolant is hot and builds pressure. Search this forum for "coolant reservoir" for several threads on this topic, like this post: https://www.jaguarforums.com/forum/x...3/#post1047587

And this video:
2) The water pump has a small weak hole above the shaft which slowly leaks when the pump is old and the shaft seal is worn. Attached is a picture of an old ~130K mile pump with coolant slowly leaking from the weep hole.

3) The thermostat housing and adjoining hoses & pipes, which you can view from beneath the car, by looking up between the radiator and engine. These posts have pictures and videos:
https://www.jaguarforums.com/forum/x...nt-leak-38696/

https://www.jaguarforums.com/forum/x...oolant-148267/

https://www.jaguarforums.com/forum/x...e2/#post845737

 

Alright guys, I don't know how to describe this to you. So they gave me a call, and said they found an air blockage in the heater core. Literally a bubble of air in the heater core that somehow had an equilibrium to prevent the coolant from exchanging IF I was at idle. When I pressed the gas, it would move coolant through because of the pressure. The purged the system of air and rather than flushing everything out, just topped off the coolant.

They are charging me for a gallon of antifreeze and tax, nothing more. He said it was likely my coolant level likely didn't appear to be very low because of the air in the core occupying a certain amount of space.

I am going to pick my car up in about 30 minutes once it is all ready, I'll post back with an update saying whether or not I have heat at idle... *fingers crossed*

 

Makes sense. When I had my X I once had teh same issue where I would get heat when running, but it would quickly get cold when stopped at a light. My coolant was a bit low. As soon as I topped off it was fine. So, hopefully that is all it is for you.

If you do have a coolant leak and your water pump hasn't ever been changed it might be a good idea to change it anyway. It's not a situation of if it will go out, it's when it will go out. Generally it seems the magic number of the pump is about 90K-100K. I had just over 100K when mine went. Started with a slight leak. I made an appointment by my mechanics to get it fixed several days later. The day came and I dropped the car off and it was fine. Then they drove it from the parking spot into the bay and in that short 100 foot trip it let go completely. Coolant was just pouring out. Talk about getting lucky.

Hope you have it all sorted out soon!

 

So I have heat again! FYI, he called it airlock in the heater core. I never would have thought of this (as I didn't know this happened). He said it was a lot of air, so if it starts acting up again I may need to inspect further. I wasn't 'very low' on fluid, but he said they definitely topped it off higher than it was.

For anyone who reads this thread in the future... here was my list of things I did:

1) Hard reset the car. Disconnected the battery for 30 minutes, then reconnected. Started car and let it run for 5 minutes without touching any A/C controls. This did not fix the problem (I read this resets the climate system, which for some people is the issue).

2) I checked the temperature of the hoses on the reservoir. If you go to page 1 and view the picture I posted, all of my hoses were hot so I knew there was hot coolant in the hoses. If there was a block in my heater core, I likely would have had 1 cold hose (as the picture shows on page 1). So scratch this from the list.

3) I removed the glove box (7 total screws, you'll need a phillips, a hex set, and hex or flathead. 3 are under the glove box(phillips) and attach the glovebox door to the dash. 2 in the back of the glovebox when you open it(hex/large flathead), and the front 2 (hex) are also the rubber stoppers so it shuts quietly. I then removed the actuator (#4, the bottom one) which is held in by 3 screws (hex). Once I did that, I turned the A/C to HI and watched the actuator rotate its' pin. Then turned it to LO and watched it turn back the other way. Took it apart and checked the gears, no broken teeth. Found out the shaft the actuator pin goes in to wasn't catching on the pin (I could manually rotate the shaft by putting a large hex piece I had from right to left). On my car, turning it to the far right is cold and far left is hot. When I did this, the temperature did change. It didn't keep the heat warm at all during idle, but it was much better than before. I suspect this was also giving out, so good thing I checked on it. So the actuator works, the blend door is functioning... what next?

4) I was preparing to replace the water pump, but decided to have my local mechanic just do a pressure test on the system to check for leaks (you can easily check for leaks at home by buying a radiator pressure testing kit for an auto store.) That way, if it was my reservoir or a hose leaking, I wouldn't have wasted the time on a water pump which didn't fix my problem. Well while doing the pressure test, they discovered a massive air bubble sitting in the heater core (called it airlock). This was preventing fluid from cycling around the system unless I was above 2500RPM. The purged the air, topped off with coolant, and all done.


Hope this helps. If anyone has questions please feel free to ask... and thanks to everyone else with helping me diagnose my car and save some money! They tahnked me for doing all the other work because it helped them get right to the root cause, and they only charged me for the gallon of coolant they used and tax (not even labor.)

 

Same issue with mine. Flushed cooling system and replace antifreeze, and heat works fine.

 

swetnK: Glad you're warm again, and thanks for sharing your learnings. I'm a little embarrassed it didn't occur to me that an air bubble was blocking the coolant flow thru your heater core.

Some time ago Thermo described how to "burp your kitty" in this post: https://www.jaguarforums.com/forum/x...31/#post157886
But I've never had to do this, because running the engine and topping off the coolant reservoir was sufficient. Evidently if enough air gets trapped in the heater core, "burping" is required (and simple, so next time, we now know to give it a try).

Live and learn.

Again, thanks for sharing, and glad you're back in the hot seat, so to speak.

 

Thanks for the help still! The first mechanic I went to said I had a bad compressor so the window was fogging because it couldn't dehumidify the air... and quoted me 2000 for the fix. So glad I got this fixed for less than 40 total