1998 Renault Laguna ventilation blowing cold

There are numerous causes , if the temp guage is reading low it could be thermostat. If the control you talk about is for hot / cold setting it could ge that which is not allowing full heat .Here are other suggestions from people with the same fault ,


Had this problem and it was air in the system, just this minute fixed it.

NOTES:
-Tools: 3/4 socket set and screw driver set
-Spare fluid
-Gloves if you have sensitive skin
-Engine should NOT be running

FIX (to make it easy require two people, VERY hard solo): nice and simple, remove the cap to the header tank and leave it off throughout, make sure the header tank is full of fluid, undo the two nuts (10mnm on the car I did it on) which hold it in place and lift it up to gain maximum pressure through the system; get the other person to undo the four bleeder valves (requires screw driver though pipes can be finger loosened, rad requires screw driver) one at a time making sure to do up the previous one before the next is undone:

-Start with the outlet from the rad (top pipe)
-The the radiator its self (located top left looking at the car. Be warned the pressure is slightly higher so don’t panic as it does flow fast)
-Then the rad inlet
-Finally the out from the matrix (valve can be located just under the air pipe from the filter to the manifold)

Keep the valve undone until there is a constant flow (prepare to loose a lot of fluid) and make sure at all times the header tank is kept high and with sufficient amounts of fluid to maintain pressure.

When the system is bled, start the engine and go for a drive to get the temperature up enough to open the thermostat and that should be it :D

Sorted.

Richard Harrison
December 2007
Blocked heater matrix is a common problem because of the way they are constructed. Unfortunately water alone does not work well, as my mechanic discovered. I flushed the system with Forte BioDegreaser following the instructions carefully. Perfect result after a couple of hours work (it involves idling the engine for 30 minutes).

Graham
October 2007
The problem is with your heater pipes being blocked (I had this on my Laguna and it's a common problem if you search Google). They need to be flushed.

You need to remove the inlet pipes from the bulkhead (engine side on the right hand side, look for 2 pipes) and flush through with a hose pipe. Alternate between the 2 pipes and watch the sludge come out. Don't forget to bleed the air out on refilling.

Hope this is useful.