Help.... 405 Problem

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coupechick
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Help.... 405 Problem

Post by coupechick » 11 Dec 2012, 14:12

Hi

I have a 94 Peugeot 405, have a bit of a problem with the heater.

The heater blows out hot air right at the vents but when you move further away from that the air is cold, really cold!. If the car is being driven, stopped and then left sitting going the heater will blow warm air and the car will be really nice and warm inside. However when you drive on again the air goes back to cold???

Anyone any ideas what may be the problem?

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spider
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Re: Help.... 405 Problem

Post by spider » 11 Dec 2012, 16:08

Welcome. :)

Just to clarify, if you sit in traffic etc the heater gets nice and warm but when you drive it cools down ?

This points to a thermostat stuck open or missing in most cases.

Does the temperature gauge work properly ? , iirc it should sit about mid point possibly a bit lower give or take a few mm, if it sits too far to the left (cold) and only really moves when you're stuck in traffic that also confirms it.

Another less likely cause is an airlock in the heater unit although I'd expect if that happened if it actually got the heater matrix hot it would stay like that so that does not seem likely.

What engine do you have ? 1.4 / 1.6 / 1.9 / 2.0 petrol or 1.8 / 1.9 D or TD

coupechick
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Re: Help.... 405 Problem

Post by coupechick » 11 Dec 2012, 16:17

Hello :)

No for instance if someone is in the car with me and for example I go into a shop/bank where there are q's when the car is left sitting taking over it will be lovely and warm when I return and get in but once start driving it cools again...... very strange......

its a 1.9 d as far as I remember......... and temperature gauge seems normal

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spider
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Re: Help.... 405 Problem

Post by spider » 11 Dec 2012, 16:24

I still suspect a thermostat.

If it was stuck open or missing then coolant can flow through the radiator all the time, so the engine never gets really warm (so poor heating) when you're driving along.

When you're stuck / sat in traffic there's no airflow from driving going into the radiator so it starts to get warm and then cools off when you drive again.

Another way of testing it is to run the engine (from cold) for about 5 minutes no more. Now feel (carefully) one of the two heater hoses on the bulkhead and then the radiator top hose. They are unlikely to be burning hot but usual precautions incase.

If the thermostat is functioning the heater hoses should be a lot hotter than the radiator hose, which may well still be stone cold at this stage. If there's about the same warmth in the radiator top hose then the thermostat is missing or stuck open.

coupechick
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Re: Help.... 405 Problem

Post by coupechick » 11 Dec 2012, 16:27

Also meant to say that there is warm air coming out the vent, if you put your hand in front of it you can feel the warm air. But as you move your hand away from it the air is icy cold....

How do I fix the thermostat? or is it a mechanic job?

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spider
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Re: Help.... 405 Problem

Post by spider » 11 Dec 2012, 16:33

You'd have to take the top of the thermostat housing off and see if its missing or replace it. Personally from the symptoms I'd replace it anyway from what you're saying.

After that it would be a flush out of the remaining coolant (if its more than a few years old) and refill with fresh. They do need to be bled carefully to expell any air, diesels especially. This will also remove any sediment and rust / choked hoses (unlikely although the tiny hose on the top of the therm housing can do this on some early models, I think yours is too new for this) can clog at the same time.

In summary its:

Drain cooling system

Remove and replace the thermostat

Flush out and refill with fresh coolant. The flushing out with a hose is really recommended if you're not sure when the coolant was last changed. Most 405 HeadGasket fails are caused by coolant problems.

It would be something to have done at a garage if you're not sure, it should not cost that much without looking I'd estimate say 20 odd for a good thermostat, about 15 to 20 for 4 litres of antifreeze and say 3/4 to 1 hours labour to drain / replace / refill.

addo
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Help.... 405 Problem

Post by addo » 12 Dec 2012, 08:14

I'd start by confirming the heater/aircon system is doing the right things.

First check the pollen filter isn't blocked. If that's missing, there may well be a "dam" of compost inside the heater box - unhelpful! Then check the heater is physically plumbed into the dash - many are bypassed in warmer months when they leak.

Then blower speed control needs verifying - that it works, and that speed may be varied with the dial.

Next I'd confirm the temperature control and recirc flaps are both working. The temperature controller specially, can be a bugger for failing - it then makes a noise like a fly in a matchbox.

If all is working OK, I'd then plug the car into Peugeot Planet and discover in real time what the climate control computer actually thinks it's seeing.

citronut
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Re: Help.... 405 Problem

Post by citronut » 12 Dec 2012, 09:26

my old N/A D BX used to do similar if the coolant level was low,

mozzy
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Re:

Post by mozzy » 12 Dec 2012, 11:01

addo wrote:I'd start by confirming the heater/aircon system is doing the right things.

First check the pollen filter isn't blocked. If that's missing, there may well be a "dam" of compost inside the heater box - unhelpful! Then check the heater is physically plumbed into the dash - many are bypassed in warmer months when they leak.

Then blower speed control needs verifying - that it works, and that speed may be varied with the dial.

Next I'd confirm the temperature control and recirc flaps are both working. The temperature controller specially, can be a bugger for failing - it then makes a noise like a fly in a matchbox.

If all is working OK, I'd then plug the car into Peugeot Planet and discover in real time what the climate control computer actually thinks it's seeing.
whats with the paslode in your avatar ???

addo
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Help.... 405 Problem

Post by addo » 12 Dec 2012, 11:54

I'm an accredited nail installation consultant, also sometimes known as an architect's labourer.

coupechick
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Re: Help.... 405 Problem

Post by coupechick » 12 Dec 2012, 12:24

Thanks for your replies :)

The heater worked fine until the car was parked up for a few years....... when it was put back on road this year the heater is not working great compared to what it used to..... I had thought maybe something was damp in it too?

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Help.... 405 Problem

Post by addo » 12 Dec 2012, 12:46

Is it Series 1 or 2 405? What year?

Did the cooling system fully dry out while it was parked up?

coupechick
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Re: Help.... 405 Problem

Post by coupechick » 12 Dec 2012, 13:18

1994 is the year not sure what series.......

I have no idea, I had kept anti freeze in it in winter tho

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spider
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Re: Help.... 405 Problem

Post by spider » 12 Dec 2012, 13:44

94 will be Series 2 assuming you're in the UK. It changed at late 91 or early 92. :)

I think the dash heater changed from rotary knob to left / right type slider at S2 and the wiper stalk, the early ones you moved it down to switch the wipers on, the later ones you moved it up to switch them on. The hazard / heated window switches were near the top and further down on the later models. Boring facts I know :oops:

coupechick
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Re: Help.... 405 Problem

Post by coupechick » 12 Dec 2012, 14:25

Yea in the UK.

It is a slider for the heater..... pure nightmare in this weather with the heater going funny lol