2007 RX400h Heater Issue

[Ridgeback]

This has been an ongoing problem for the past couple of years, but brought to a head with the recent cold snap.

I was chiselling off the frozen crust of yesterdays frozen sleet, with the engine running and vents on the front screen.

After a few minutes the heat started to come through the screen vents and thaw the ice.

After a few more minutes the heat from the vents was getting quite hot.

I changed the airflow to the forward facing vents and it was getting quite toasty.

Now comes the problem, when I drive off it blows cold, irrespective of the temperature setting.

The only time it will blow hot again is when I get on to a road where I can floor it, but shortly after taking my foot off the pedal, it goes back to cold.

Does this have an electrical or mechanical water pump?

If it's mechanical, how does the heater work if the engine switches off during a long downhill decent or on Battery mode in slow moving traffic.

As a side, I noticed that the folding mirrors were not opening.

The freezing sleet had built up a 20mm block of ice on the mirror bracket, preventing the mirrors from opening.

It's quite a confined gap, so I had to use a small screwdriver and carefully chisel away the ice.

[royoftherovers]

50 minutes ago, Ridgeback said:

This has been an ongoing problem for the past couple of years, but brought to a head with the recent cold snap.

I was chiselling off the frozen crust of yesterdays frozen sleet, with the engine running and vents on the front screen.

After a few minutes the heat started to come through the screen vents and thaw the ice.

After a few more minutes the heat from the vents was getting quite hot.

I changed the airflow to the forward facing vents and it was getting quite toasty.

Now comes the problem, when I drive off it blows cold, irrespective of the temperature setting.

The only time it will blow hot again is when I get on to a road where I can floor it, but shortly after taking my foot off the pedal, it goes back to cold.

Does this have an electrical or mechanical water pump?

If it's mechanical, how does the heater work if the engine switches off during a long downhill decent or on battery mode in slow moving traffic.

As a side, I noticed that the folding mirrors were not opening.

The freezing sleet had built up a 20mm block of ice on the mirror bracket, preventing the mirrors from opening.

It's quite a confined gap, so I had to use a small screwdriver and carefully chisel away the ice.

20 mm is 3/4 of an inch.......of ice  Jim ?  Must have been cold in Cheshire.

[Ridgeback]

It was -5C at 9.00PM yesterday and stayed around -3C for most of the day, and then started to sleet around 4PM

The sleet must have froze on contact and built up layers, never seen this before in the 10 years I've owned it

[royoftherovers]

1 hour ago, Ridgeback said:

It was -5C at 9.00PM yesterday and stayed around -3C for most of the day, and then started to sleet around 4PM

The sleet must have froze on contact and built up layers, never seen this before in the 10 years I've owned it

you mean 9.00am ?

[welland]

Interesting problem that I have not experienced with mine. Interested in finding out the cause.  

I wonder if the heater gets heat from the engine, or from the inverter? 

[welland]

A couple of thoughts about this problem:

Does it matter if the A.C. is on or off?

Does it matter which output vents you have chosen?

Does it matter which fan speed is chosen?

Is it the same if you use the auto setting?

Is it the same when the temperature is set to HOT (eg 25C), and when it is set warm (eg 21C)?

Does it make any difference when passenger temps are set the same as the drivers temps, or when passenger temps are different to driver's?

[Ridgeback]

I've tried every combination know to man, in the slim hope that one of them is causing it to the problem.

It seems once it's up to temperature it switches off, even with the temp controls on max, I've even tried left on min and right on max, AC on/off, then vice-versa.

Maybe there's a cabin sensor, with an intermittent fault that thinks the internal temp is too high and shuts off the hot water, grasping at straws now.

[Herbie]

5 hours ago, Ridgeback said:

As a side, I noticed that the folding mirrors were not opening.

The freezing sleet had built up a 20mm block of ice on the mirror bracket, preventing the mirrors from opening.

It's quite a confined gap, so I had to use a small screwdriver and carefully chisel away the ice.

Put some warm (NOT HOT) water in a sandwich bag/ziploc bag and hang it in the confined gap. You could also use another one to clear the screen if you don't like to use deicer spray due to smearing.

[Ridgeback]

I had thought of that, but I was running late for a Xmas concert where there was limited parking.

It was only when I was leaving that I noticed the mirrors weren't opening, and didn't have the time to go back into the house and get a ziplock bag of warm water.

Holts de-icer was total useless on the windows, did nothing to thaw the ice, ended up using a scraper