I did a search for info on this issue but did not find so thought I would ask.
My 2006 LR3 with about 175k has an issue with the “Prog” defrost feature. Unlike my 2003 Range Rover, which when I press the Prog button it will clear the windows in about 2 minutes, my LR 3 will not clear at all, except for the very rear window. That will melt the ice pretty rapidly. But no melting on any of the other windows. The indicator lights turn on for the defrost and the fan blows on high but no hot air comes out and the electric grid in the glass save for the rear window does not come on.
Wondering if this has to do with the issue folks have with the clogged heater core? I haven’t flushed mine yet but will soon to see if that helps. Thanks in advance for any help.

 

Okay, so what prog does is:

• rear screen heating on
• front screen heating on
• fan speed and air to front screen

You need to triage and troubleshoot each of these separately.

front screen heating depends on two fuses in the engine bay (don’t remember which) and each side of the screen has its own power feed (cable) and a relay. It should be possible to determine to what point you have continuity.

As for fan/cabin temperature, you can’t get hot air until engine is up to temperature. The heater core (or matrix however you want to express it) depends on the coolant to be warm. If your heater core is completely obstructed/clogged I would imagine this to always be cold even if the engine is warm. Usually the LHD driver’s side tends to be lukewarm/cool/cold if an obstruction is present while the LHD passenger side tends to stay warm.

If you cannot get engine up to temperature (so your engine temp dial is not midline after a suitable time) you most likely have a problem with the thermostat.

 

I will add two small things, the front heated windshield can degrade over time resulting in few, if any, lines working. As mentioned, each side is separate though and one side may work better than the other. Failing lines are VERY obvious when fogged up. Also make sure you even have a front heated windscreen, if it possible you do not.

Also the AC system must be work well. AC is used to dehumidify the air and help clear windows. If the AC does not work well or at all, it will take much longer to dry the interior.