"Rest" heater is pathetic

[concordepilot19]

My "Rest" heater is only blowing out tepid air. It used to give out good warmth for about 20 to 30 minutes from a hot engine, now it's down to 2 minutes. Could it be due to the icy blast outside right now, or something worse ?

 

[Dieselman]

Possibly the small pump that pumps the water has gone South so you only get the heat left in the matrix.

 

[miro]

My "Rest" heater is only blowing out tepid air. It used to give out good warmth for about 20 to 30 minutes from a hot engine, now it's down to 2 minutes. Could it be due to the icy blast outside right now, or something worse ?

It only blows the temp set in the air-con dial. If the interior is warm it wont do anything. Did you dial up the hottest air settings ?

 

[prprandall51]

Have you changed your polen (spelling?) filters? Once these clog up the whole heating system is incapable of providing truly hot or truly cold air. The air flow drops significantly, too.
(From my experience in a BMW 5 with REST, I assume it's the same in an MB)

 

[concordepilot19]

Pollen filter changed as per schedule.

Dials up to max makes no difference.

Plenty of heat once the engine is running again.

I wondered if there was a pump involved as convection alone would not be enough to circulate the contents of the block or the rad.

Do you know where it is located ?

 

[concordepilot19]

Found it ! It is mounted on the RHS of the engine bay under the expansion tank and next to the turbo heat shield.

It wasn't working so I squeezed the water pipes connected to it until I could hear the thermostat air bleed valve rattling and the pump started running and the hot water solenoids started solenoiding.

The test will be to see if it works on its own next time, or whether the armature is phuqued.

 

[concordepilot19]

Amazingly it is still working OK.

Soon I won't need it as the weather is going to be great between now and November (not).

 

[panason1c]

The motor on the small 'rest' heater pump only works after i give it a sharp 'hit'...i have to do this every time i need it to run....do i have to renew the whole assembly or can the motor be stripped down?

 

[panason1c]

Well, i've stripped the small 'rest' impeller/motor down and the armature brushes are worn out....can anyone tell me where i can obtain new 12v motor brushes?

 

[1998K]

Well, i've stripped the small 'rest' impeller/motor down and the armature brushes are worn out....can anyone tell me where i can obtain new 12v motor brushes?

may be Shude can give you some help on this.

 

[GordonTarling]

My "Rest" heater is only blowing out tepid air.

Maybe the 'reheat' isn't working!

 

[panason1c]

Fixed it! Bought some oversize brushes (£4), filed them down to size, soldered the tails in and job done....saved £90 on a new motor!

 

[panason1c]

Back again!!.........rest heater motor/pump working but i have noticed that the motor/pump is running all the time whenever the engine is running!!.....is this normal?...might explain why the brushes were worn out in the first place.....the motor/pump runs as normal when i select 'rest' and the engine is off, i cant think why it should also run when the engine is running.... :bannana:

 

[Dieselman]

The pump should run all the time to pump the coolant to the heater matrix.

 

[panason1c]

The pump should run all the time to pump the coolant to the heater matrix.

I'm not sure that the pump should run all the time, the interior heater worked perfectly before the pump was repaired, and anyway, the 'engine' water pump would pump the water around once the engine is running........

I've since noticed that the motor/pump continues to run for a few minutes AFTER i stop the engine .....if someone has a rest function on their ML please can they tell me whether the 'rest' pump runs when the engine is running?
Thanks

 

[panason1c]

Well, it seems that it is normal for the pump to continue running for a few minutes after stopping the engine, apparently this is to facilitate an even engine cool down and avoid any 'hot' spots.....the pump is also set up to run when the engine is at low revs to keep water flowing through the heater matrix...(ref' Dieselman..(-

And, of course, the pump runs when the "rest" function is selected.