Peugeot 405 Only blowing cold air!!!

[Dhuper]

Hi, I've got 405 2.0 GTX Petrol 1994, the heater only blows cold air now this started some time ago, when it happened it was low on coolant, I've been reading some of the letters in this section, is the problem due to air trapped somewhere? any help will be (warmly) greatly welcome.

 

[joe-90]

It's usually the thermostat that's no longer operating and the cold weather has highlighted it.

When the engine is cold start it up with the bonnet up. Place your hand on the radiator. If it gets warm straight away - then it's the thermostat. If it stays cold then gets hot suddenly when it reaches the right temperature - then it may be an air blockage.

 

[InTheBeginning2007]

A lot of cars have a blead point in the engine bay, where the water pipes go through the firewall and inside to the heater.

 

[Dhuper]

Hi, The pipes from the thermostat going in to the car are hot when car has warmed up, and there is a metal pipe i can just touch behind the glove box and that's also hot, so heat is going behind the dashboard but not through the blowers, it couldn't just be the hot/cold selector could it? perhaps it's stuck in the cold opening, there is a ball valve with a (cap like a tyre valve cap) on top of the thermostat I unscrewed it a little by hand and water started to come out is that the bleeding point? some told me it's either the matrix or the hot/cold selector is stuck in cold and either way the dashboard has to come off, is he right??

 

[wp8800]

You say a 1994, is it the new or old model? Does it have a roof aeriel for the radio or is it on the back quarter panel?

If its the later model, the heater matrix can be done without removing the whole dash, its a bit tight but it can be done.

The cap on the thermostat housing is a bleed, but there is likely to be another on somewhere on the heater pipes as well.

 

[Dhuper]

You say a 1994, is it the new or old model?  Does it have a roof aeriel for the radio or is it on the back quarter panel?If its the later model, the heater matrix can be done without removing the whole dash, its a bit tight but it can be done.The cap on the thermostat housing is a bleed, but there is likely to be another on somewhere on the heater pipes as well.

Hi, Yes it's the newer model with the roof aerial, when you open the glove box you can see 2 metal pipes and they are hot, what does the matrix do?? is it a big part, and could it be the hot/cold selector? is there some way to make sure which it could be?

 

[preditor]

quick cure remove steering wheel cover and cover under bottom of dashboard. use a torch or lamp and look high up on the heater box and you will see a rectangular box with a cable coming out this is the flap motor undo the 2 screws and pull of the motor move the lever down and jam some sponge to hold it down you will then have max heat or jam it up for cold.
i have had intermittant air con failure for months when it fails the heater is stuck at the temp that it fails when it starts to work if i set temp to max the next time it fails it is them stuck at full heat the car is not worth much now and the chances of finding the fault are almost zero even if you pay specialists £100,s this way you at least get heat for the winter

 

[Dhuper]

quick cure remove steering wheel cover and cover under bottom of dashboard. use a torch or lamp and look high up on the heater box and you will see a rectangular box with a cable coming out this is the flap motor undo the 2 screws and pull of the motor move the lever down and jam some sponge to hold it down you will then have max heat or jam it up for cold.
i have had intermittant air con failure for months when it fails the heater is stuck at the temp that it fails when it starts to work if i set temp to max the next time it fails it is them stuck at full heat the car is not worth much now and the chances of finding the fault are almost zero even if you pay specialists £100,s this way you at least get heat for the winter

Hi thanks for that, you're right about, the repairs will probably cost more then the value of my car, I'm sorry to be a pain but what you mentioned is that a hard thing to do, I am a bit of a novice ( remove steering wheel cover) is that the bottom part of the steering? and (under bottom of dashboard) which one is that? and the heater box is that behind the hot/cold selector section in the middle of the dashboard? if possible could you please explain to me how to do this?

 

[Dhuper]

Hello and a big thank you to you Preditor, I did what you said and I got heat straight away, I owe you a couple of pints

 

[libby lou lou]

me is suspicous

 

[Dhuper]

me is suspicous

Hi, suspicous as in!!

 

[Agile]

That problem on this model can also be an early warning of cylinder hear failure caused by no water in the top of the engine!!!

There is a less known method of filling them properly.

Also this problem will appear if the cylinder head is lasking POC into the water.

Tony

 

[N8813714]

I pretty much have the same problem, my heater only blows cool air, but warm air on on the lowest setting, now I've been reading tis forum days now and see that the two metal pipes behind the glovebox are mentioned, i touched this pipes this every evening, yip very hot... so what next, do i have to disaemble the lower part of he steering collum and locate these two ?, levels?, or could it be something simpler??

the radiator is hot, so i presume its not an airblock, but if honest i know what one end of a screwdriver from another, please help my car is freezing and seeing a i do more night than day driving, as you can imagine its very very cold...

regards

mark

 

[wilkinsonbaz]

hi i had the same problem during summer mine was stuck on hot, an easier way i found to get to the heater flap box is via the floor well, take off the cover that surrounds the peddles it may have been taken off already there are just 2 wire clips hold it in place, use a torch and look up on the side of the heater box about level with the heater controls you should see the flap control box it's about 2"X3" and says valeo thermique on it, it's held on with 2 torx headed screws there's a little multiplug for the wires bit fiddly but take it off and you will see the flap to control the hot and cold air, I opened the control box carefully removed the gears (make a note of their positions) and motor, made sure the motor turned using my fingers put a little 3 in 1 oil on the motor shaft put it all back together tried a few times just reconnecting to multiplug it worked, refitted it, worked okay since.
if the box doesn't work you can always just wedge the flap with something
hope this helps someone
john