2013 RR L405 5.0SC - No interior heat

[siegrisd]

Hi, all,

I have a 2013 L205 5.0SC and I have no interior heat. Here's what's recently been done: new front coolant pipes, new oil cooler seal, new rear crossover pipe, vacuum coolant refill. I've pressure tested the system and I've tried both of the processes in the Range Rover service manual for manual re-filling as well as vacuum filling. The upper coolant line that goes to the heater core is nice and not when the engine is up to temp, but, the lower line is still relatively cold. I've bled the system from the upper bleed screw that's near the left rear corner of the engine (passenger side, LHD), and the bleed screw that's just aft and below the coolant reservoir. The coolant that escapes from the upper bleeder is nice and piping hot, but, the coolant that escapes from the lower bleeder near the reservoir is still rather cool. Prior to replacing all of the coolant lines, the heater worked perfectly.

I've run the test procedure for the blend doors and no codes have come up.

Is there a way to test the coolant temp sensor on the rear crossover pipe? If this is defective, would it cause the no-heat problem?

Thanks very much for your help.

 

[Rover Range]

There's a hot water valve that can get stuck closed.
It's located right under the hood, behind the right front strut.

 

[siegrisd]

Thanks for your help!

I took a really careful look this weekend and wasn't able to find it the valve that you're referring to. All I see are the water pipes and hoses that run into and out of the heater core. I've traced all of them and there isn't a valve inline with any of the lines (at least not one that I was able to find). The hot water side (labeled "top") that feeds into the heater core comes right off of what looks like a swirl generator on the heater manifold/crossover pipe that connects the back of the heads together. There's the bleeder valve on on it, and then it splits to the rear, auxiliary heater system for the rear seats. The cold water side (labeled "btm") runs from the heater core, to the tee that comes from the rear auxiliary heater, and then it runs through soft lines across the underside of the radiator and into the thermostat housing. There aren't any other valves on that line between it and the thermostat housing.

I checked again, and there isn't any heat coming from the rear, auxiliary heating system, either. The cold water side is still cold even after taking an extended drive. Since there are just two tees that service the auxiliary heater, am I right to deduce that if there was a blockage in the main heater core, at least there'd be heat from the auxiliary system?

Otherwise, the coolant level is perfect, the engine comes up to temp perfectly, it's not overheating, the coolant temp indicator is nice and steady and stays dead in the middle of the gauge, and there are no other symptoms at all other than there not being any heat from either of the climate systems.

I'm completely baffled.