Crap heater in car

Andy From Sligo

hello the wife's renault Clio Mk2 2003 (no air con) has a crap interior heater in it - with the knob turned on full it dont get roasting no-where near it. and also not brilliant at de-icing the screen in the morning quickly ,

Could it be dust and ****e on the heater matrix or could it maybe be the tubes inside the matrix clogged up with crud? any ideas?

the engine reaches temp OK and the coolant level stays up in the middle when the engine has reached temperature .

I have a bottle of holts speedflush somewhere , that would be the easiest of the 2 options of taking apart the dash and cleaning the matrix heater or flushing out the heater matrix. - if I wanted to use the speedflush can you drive around with that in the system fine with the antifreeze or will I have to drain the whole system down and put the speedflush in and then flush it all out?

I suppose the third option could be the cable from the heat control knob to the heater unit needing adjusting but how likely could that be?

Thanks.

dooroy

First thing you should check is the pollen filter (cabin filter). They are rarely changed and get clogged up over time resulting in a very poor airflow into the car.
There are clips on Youtube showing where it is and how to change it e.g.
https://www.youtube.com/watch?v=sMIG8mfOTGw

Andy From Sligo

dooroy wrote: »

First thing you should check is the pollen filter (cabin filter). They are rarely changed and get clogged up over time resulting in a very poor airflow into the car.
There are clips on Youtube showing where it is and how to change it e.g.
https://www.youtube.com/watch?v=sMIG8mfOTGw

oh yeah, thanks I forgot to mention it but when she bought the car in the summer that is one of the first thing I checked and there was no pollen/cabin filter fitted at all in it. I think either some people/garages chuck them out when checking and dont bother replacing them or the manufacturers dont add them in the first place (on a non air conditioned vehicle) .. yeah so anyway , not one in there .

DublinDilbert

Check the pipes feeding the heater matrix to see if they get warm as the engine starts to warm up. Also feel the top road hose should be cold till thermostat opens.

Often the stat fails slightly open so little hot water gets to the internal heater.

Not sure if this model has a control valve on the heater flow return, some do, others do it with the air flow over the matrix in the cabin.

Should be fairly easy to figure out what's wrong.

Andy From Sligo

DublinDilbert wrote: »

Check the pipes feeding the heater matrix to see if they get warm as the engine starts to warm up. Also feel the top road hose should be cold till thermostat opens.

Often the stat fails slightly open so little hot water gets to the internal heater.

Not sure if this model has a control valve on the heater flow return, some do, others do it with the air flow over the matrix in the cabin.

Should be fairly easy to figure out what's wrong.

thank you - yes I will check all that . I never though about that it could be the thermostat.

rex-x

Heater matrix is likely internally clogged, happens fairly regularly on these and replacement is the only fix!

endacl

First thought when I read the thread title was “but why would anybody want their crap heated?”.

Andy From Sligo

endacl wrote: »

First thought when I read the thread title was “but why would anybody want their crap heated?”.

haha yes thats where it gets very important to explain properly in the title

Andy From Sligo

rex-x wrote: »

Heater matrix is likely internally clogged, happens fairly regularly on these and replacement is the only fix!

any use in trying to use the speedflush ?

Fordcspri23

Couple of dishwasher tablets in cooling system for a few days is worth a punt. Better used when oil has contaminated the cooling system but may do some unblocking.

DublinDilbert

I've unblocked heater matrix before with a garden hose. Disconnect each side of the matrix and flush both ways.

rex-x

Andy From Sligo wrote: »

any use in trying to use the speedflush ?

You can always try but these tend to rust from inside out

Andy From Sligo

DublinDilbert wrote: »

I've unblocked heater matrix before with a garden hose. Disconnect each side of the matrix and flush both ways.

ive got a pressure washer - might be better to do it with that? , or could the power of it do more harm?

rex-x

I wouldnt go putting a pressure washer in there, they are only designed to handle a few psi

DublinDilbert

Just disconnect flow and return and put the garden hose on to one side at a time, when you have it connected crank the tap open.

CJhaughey

I did that with a Mk2 Golf, flushed the matrix and caused a leak in the matrix.
The dirt must have been blocking the hole.

Andy From Sligo

CJhaughey wrote: »

I did that with a Mk2 Golf, flushed the matrix and caused a leak in the matrix.
The dirt must have been blocking the hole.

yeah it possible isnt it

blackbox

Fordcspri23 wrote: »

Couple of dishwasher tablets in cooling system for a few days is worth a punt. Better used when oil has contaminated the cooling system but may do some unblocking.

I wouldn't chance this myself. Dishwasher tablets are alkaline and likely to corrode aluminium.