Hi - Recently bought my rr [4 months ago] and seems there is an issue with the cabin heating - from cold gets up to temperature then seems to cool down whilst running - nothing altered on the controls and engine temp in the ok band. - feels for all the world like an air lock?
Had the air con checked out and all ok in that department, and when you click the air con into active, doesnt seem to alter things - just stays cold.
Suggestions guru's please
Thanks

 

Low coolant, a large air bubble, or a sticking thermostat could contribute to all of this. Helps to know model year and miles (kms).

 

Thanks. It's a 2000 with 110,000 miles on the clock. Runs on lpg. Coolant level is fine and holding. Had the heads done by previous owner (seen receipts)

 

I'd vote for sticking thermostat. You could attach a scanner or ultra gauge and watch the temps in digital form, and see exactly how it is changing. A stuck open thermostat will show up as warms up, but below nameplate rating for stat, and won't get past the nameplate rating usually. The open stat also changes the water flow in some cases in the heater core.