Help! It got cold out!
I just purchased this car. I know I have some electrical issues, but any tips on this? My dashboard temp gage, after the car is warm still reads zero. Then, sometimes, slowly, it climbs to Normal, then it soon drops off to zero again. SOMETIMES it will blow warm, not hot for a minute then blows cold again.
Does the heating system use the temp sensor from the engine to control hot air?
any leads appreciated. I will attach a foto of a mystery item from under the hood that has antifreeze running to it. It is electrical and sits above the alternator.
thank you, tom
p.s. Inside the fans and other buttons work, I can set the temperature up to HIGH, just blows cold. Defrost setting sets the fan higher. Seems to work except for heat. Is it a vapor lock?

 

Cluster gauge and heating are separate issues. If your dash gauge temp shows low after 15 minutes of car running, you either have something wrong with the thermostat or the temp sensor died. Gauge runs of the sensor with a single wire at the front of the engine, near the thermostat housing. Check the wiring or swap the sensor, you can plug in an OBD scanner and check temp off the engine ecu sensor, this is the separate sensor and its next to gauge sensor, this one has two wires.
Your interior heating sounds like it will be down to auxiliary heating pump, this is on the left of the car hidden under intake elbow plastics, its plug is next to bulkhead so you can disconnect it, plug it directly to a battery and see if it makes any noises, if it doesn't - take it out and replace carbon brushes in it to fix it, or replace it with a new one.
Of course you will only have heating if the engine actually heats up.

 

Thank you so much. this is awesome, I have a lot of checking to do. I will report back. I have to tell you, I am coming from working on an 87 BMW 325, so I'm used to a lot less stuff under the hood. This is most helpful, and a learning experience for me. Thank you again, tom

 

There is a self test that someone made A Youtube video


The test can be seen here in writing on page 110

T703 BOOK (jaguarrules.ru)

Your codes are here after test

14-10 (jagrepair.com)

The test does not see everything but it does cover the bases

to feel the rubber hoses after the electric heater pump may not show you accurate info as heated coolant will flow after a certain high engine RPM

The cabin temp sensor has a mini fan that should not be cleaned with a spay solvent , dries the fan bearing out to fail later

The brushes are cheap and sourced from California as part # 33A

.15" x .15" x .35" BRUSH 33A (eurtonelectric.com)

Editing

 

Very common for the thermostat to stick open on these. Lots written here on lack of heating. Heater cores clog up and need to be backflushed, aux pump brushes wear out. Watervalve can fail closed. But by far, the most common is T=stat stuck open, then aux pump brushes worn out, then heater core clogged, then maybe WV failed.

Search for the TSB's posted by Motorcarman.

 

The X300 heating system basically works like this

Heated coolant is drawn directly from a pipes inside the engine along a cylinder wall sleave

This fluid is drawn by a dedicated electric heater pump that runs at all times with heat selected

A water solenoid / valve will modulate open and closed to maintain the cabin temp selected referencing the cabin temp sensor

You can test the coolant solenoid / valve with a 9 volt battery and feel for a click

The electric heater pump can be tested with a battery charger but put it on the lowest 2 amp setting

 

The heater only begins to work when there is heat. The heater fans don’t kick in until there is warm water in the system, hence you can drive for a few minutes in the morning before they power up. Where the hvac gets its water temperature reading from, I don’t know, but it could be the same as the temperature gauge. (But remember, there are two coolant temperature senders, one used by the ECU, and one by the gauge) When you set the heater to “HIGH” you bypass the temperature control.
As has already been suggested, the thermostat sticking open would seem like a distinct possibility, and it would fit the symptoms. A cheap laser temperature scanner would allow you to see whether there is heat in the radiator etc, and is a generally useful thing to have around.

 

i had no heater when i got my car.
i replaced the thermostat - no bueno.
i replaced the brushes in the heater pump - BINGO!
both of those are cheap and relatively easy repairs.

there is plenty of info around in regard to the heater pump brushes change.
it is a relative simple fix, take out the pump, open it up remove the worn brushes, place and solder in new ones, put it together and off you go.

 

But all the responses warm my heart, almost as much as my cabin heater does now WITH A THERMOSTAT!, as was pointed out in several responses, you need heat to get heat.
I will keep this info in mind for my next problem.
Best Regards,
tom
p.s. I will confine future questions to the 300 pages
:-)

 

Good Morning All,
I still don't have heat, even with the new thermostat, The dashboard shows a warm engine, but still no heat.
I took off the auxiliary pump, it was full of coolant,, The motor hummed when jump powered, I am getting 14.4 volts at the black plug (yellow nd black wires) with car running and warmed up.
I took apart the impeller and all looked good so I put it back together and put the pump back where it was.

The hoses around the pump got warm, but still no heat, and them the hoses seemed to go cold again.. Cabin still ice cold.

I jumped the solenoid (white plug blue black wires) with a 9 volt battery, NO CLICK. With the car running and warm, get 6.6 volts from the white plug.

So maybe the solenoid? Does it come off its mount with coolant leak or does removing the solenoid cause a spill of coolant.

Thank you so much, I am just getting back to this problem, but lots of stuff on the car has been repaired. So thanks again.

tom

 

The solenoid has coolant on the gate so yes there will be spillage.

You can remove some coolant from a stop **** / drain on the radiator lower right side on the very bottom surface.through a hole in the sheet metal frame that runs under the lower radiator

Your still going to get some spillage from coolant trapped in the hoses