Turned on the heat for the first time in 6 months but its not blowing hot air. I did some reading and saw it might be the "Auxiliary Water Pump". Any thought on this before I purchase this and install it?

Hi dvdpsycho. Welcome to the forum. A little more background info might help us help you. What have you checked and ruled out so far? Have you checked coolant level in the reservoir? Recently serviced the cooling system in the off heating season? Do either of the heater hoses feel hot or warm? Infrared temp reading on inflow hose and outflow hose would help.

At the radiator, the bottom hose is the output to the heater core and the upper is the return. At the firewall, the hose further left is the heater input and the right side is the return. I don't recall if you can reach it safely with your hand and mine's tucked away for the winter so I can't check, hence the request for temp readouts.

I checked the coolant level, that was fine. I haven't serviced the cooling system recently. I'll check tomorrow and see if I can reach the heater hoses to see if I can feel any heat.

sure, also consider an Automotive stethoscope. You can probably safely put it against the pump and hear if it's humming. You could also have a blocked heater core. I any event, you need to pull the top hose to access it. pretty simple from there. Keep us updated.

Sorry for the long delay. I was able to feel the heater hoses going into the firewall and both are crazy hot. I'm thinking it might be something with the doors in the vent. I'm getting a little bit of hot air out of the passenger side front defrost but not anywhere else. I was thinking the door flaps that direct airflow might be stuck. Does this make sense? I live in California so I've had the cooling on and not the heater at all until last month when it started to get in the 60s (I know real cold outside)

With the engine running and fully warmed up, park the car and try this.

Close all the vents fully and manually set the temperature to maximum heat. Then turn the fan speed knob and repeatedly vary the speed between maximum high and minimum low. Alternate doing the same thing with your air conditioning. Continue to do this for a few minutes. Open the windows if you get too hot.

If the vent flaps were stuck, hopefully, this will free them up.

OK so heater hoses are crazy hot which likely means your Aux pump is fine. When the A/C is on, does it blow cold air through all the vents? Have you tried cleaning the interior temp sensor?

https://www.jaguarforums.com/forum/x...ry-low-224770/

There's 5 servo motors which move the air direction flaps. These, and the temperature are controlled by the ATC (Air temperature Control) Module. Lots of options for failed module, temperature sensors or sticking flaps preventing air flow.

Graham