Laguna 94 with lukewarm heater airflow.

Honest John Back Room » Technical matters
View Threaded
Thu 17 Oct 2002 21:26
Laguna 94 with lukewarm heater airflow. - Biggee
Just bought a 94L Laguna 1.8 RT Petrol, full service history, 90,000 miles. Dont know a lot about cars but trying to save some dosh by using the haynes manual and a local mechanic to show me the ropes.

Problem I have is that the heater blows hot air for about 6 seconds then diminishes to a lukewarm flow. If I stop the fan for a few minutes then turn on again it its much hotter for a few seconds then lukewarm again. It also takes a bit of time from a cold start to get any heat whatsoever. There is no aircon on this model of car.

I have replaced the thermostat, and having looked back over the vehicle service history, see that the heater matrix was replace already.

Is this possibly the cause again, or is there anything else I could try?

Any help would be appreciated.
Reply | Report as offensive | Link
Thu 17 Oct 2002 21:35
Laguna 94 with lukewarm heater airflow. - Doc
Could be air in the system.
Try looking for bleed valves. (See recent post)
Additionally, squeezing the hoses sometimes helps to extract air.
Reply | Report as offensive | Link
Thu 17 Oct 2002 21:54
Laguna 94 with lukewarm heater airflow. - David Davies
The problem as you have described it suggests that you have a poor coolant flow through the heater matrix.The first thing to try is to completely flush out the entire cooling system to get rid of the dirty rusty coolant which all Renaults are prone to.Use a fairly powerful mains hose pipe until you get clean flow through all pipes and hoses(could take some time).Then fill up with antifreeze mix and ensure no air locks in system.
When engine is hot feel the temperature of the heater inlet and outlet hoses,they should BOTH be so hot that your hand recoils when you grip them.If you do not get this condition,as the heater matrix has already been renewed,it could be a water pump problem.Would be worth renewing this anyway at 90k miles.Let us know how you get on.
David Davies (Tune-Up Raglan)
Reply | Report as offensive | Link
Thu 17 Oct 2002 22:20
Laguna 94 with lukewarm heater airflow. - Biggee
Thanks to both replies to this. I nipped outside to have a quick check, and the hose at the top of the radiator got extremely hot. Opened the bleed valve at the heater matrix, and coolant came through.

On squeezing the raiator hose, the level of liquid coming outof the bleeder valve inscrease. Added a little more lcoolant to the expansion tank and went into the car to see if all was well. Air was colder than ever!

Will try to get a proper look in the morning, and perhaps get some assistance with flushing the system, and replacing the coolant.

Thanks again for your help and speedy reply.
Reply | Report as offensive | Link
Fri 18 Oct 2002 13:05
Laguna 94 with lukewarm heater airflow. - bernie
If you think that the airflow is reduced when not in recirculating mode I suggest you look at the pollen filter.It will be clogged.If you dont know where it is,then open bonnet,look at the grill under the windscreen and remove the small section.Underneath is a cover,below which is the offending item.

I wish my heater matrix had been replaced,sigh!!!!!!
Reply | Report as offensive | Link
Fri 18 Oct 2002 20:58
Laguna 94 with lukewarm heater airflow. - Cyd
I suggest that after a good flushing with the hose you run the car for a couple of days with just water and two bottles of Rad Flush. then flush thoroughly with hose again. Then refit fresh coolant.
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide