[Tutorial] Heater controls DIY repair

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alargeau
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[Tutorial] Heater controls DIY repair

Message par alargeau » 02 janv. 2010, 17:06

Hello everyone,

The heater controls are quite tricky on the 309 and cause some problems when they are old. So, here's a chance to understand how the whole system works and solve the problems you may encounter.
This tutorial deals with the "B" system which equipped all facelift models. There are also a "B" system which equipped the non facelift 309s (and which is not that different from this one) and a "C" system which equipped 309s with air conditioning (which is not that different from this one either).

The heater system is composed of two units: the main heater housing and the blower housing.
Air coming from the exterior goes into the windshield grille, then goes into the blower housing and finally into the main heater housing so that it will come out from the vents you chose.

Here is the main heater housing:
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Red is where the heater controls are.
Blue represents the heater matrix or radiator, whatever you call it.

Here is the blower housing:
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Red represents the air blower motor.
Blue represents the control module.

When assembled, those two units look like this:
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Obviously, the system differs from left hand drive to right hand drive models.

The third element is the heater controls which has three knobs:
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1. the left knob controls the main heater housing and redirects the air where you want it to go out.
2. the central knob controls the blower housing and controls both the exterior vent and the air blower speed.
3. the right knob controls the main heater housing and redirects the air either to the heater matrix (so the air will be hot) or avoids the heater matrix so the air will be cold.

In short, each housing has two functions:
- The main heater housing redirects the air to the vents you want it to go out and it redirects the air also to the heater matrix if you want hot air.
- The blower housing opens or closes the exterior vent (situated behind the windshield grille) and controls the blower motor.

Let's see now how the heater controls work. First of all, if you remove the knobs and the above heater control plastic, you will see this:
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(Note that I took a picture of my 309 GTI heater controls which is equipped with A/C. If your car is not equipped with A/C, you should have a "B" system)

But what is interesting is on the other side:
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My heater control was the first one produced for facelift 309s so there is a colour distinction. The black plastics (right and left) control the main heater housing whereas the grey plastic controls the blower housing. In later models, all plastics are black and are quite better, you'll understand why.
As you may know, the heater controls of the Peugeot 309 operates mechanically, it means there are cables which operate both the main heater housing and the blower housing. Actually, there are three cables (since the heater controls are reversed, we will go from right to left):
- the first cable operates the main heater housing and redirects the air where you want it to go out (on the right on the above picture)
- the second cable operates the blower housing and opens or closes the exterior vent (middle)
- the third cable operates the main heater housing too and redirects the air to the heater matrix if you want hot air (left)

Let's discuss the problems now.
If you have problems turning a heater control knob, there are two mains causes. If the problem comes from either the right or left knob, it's a cable problem. Either the cable which operates the left or right knob is damaged or it's not well maintained by the metal clips. You should then take a look at the cable.
If you have problems turning the centre knob, it's a bit more complicated. The main problem with this knob is that its composed of two plastics which don't really like each other. The main problem you may encounter is the impossibility to turn the knob from right half to left half and you may feel a hard point in the middle.
To fully understand the problem, we have to remove the grey plastic which looks like this (we'll call it plastic 1):
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You should then see this (we'll call it plastic 2):
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As you probably understood, the small head on plastic 2 goes into the path in plastic 1. Plastic 2 holds the cable which operates the blower housing, opening or closing the exterior grille vent. Plastic 1 is designed in such a way that it maintains plastic 2 in the same position when you turn the knob on right half and thus only moves it on left half. So, there is friction and friction between those two plastics is the problem. The cable attached to plastic 2 is quite short and quite hard to move too, so it makes a pressure on it holding it down and thus lowering the small head which is not well aligned to its path. Actually, the more you turn the knob to the left, the more the small head on plastic 2 goes out of its path. And you have probably tried to turn the knob anyway and you then felt that it turned loose because the small head went out of its path. You can access those two plastics by removing the plastic cover which is just above the radio but you won't solve the problem.
In order to solve the problem, you've got two choices. Either buy a new heater control at any Peugeot dealer, you'll spend approx. €70 (or £50) but I can assure you you won't regret or you can find one at a scrap yard. They don't cost much and you can take one out of a Peugeot 205. If you find one at a scrap yard, make sure all plastics that operate the cables are black. Black means later models and better quality. In both cases, don't forget to thoroughly (oh yes, thoroughly!!!) lubricate the path where the small head goes otherwise the part won't last long.

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Here is another important part, the control module:
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It is situated near the blower, on the passenger's side. If it's near the blower it's just because the module is cooled down by the blower. Never operate the ventilation system when the control module is removed!!
If your control module is faulty, then you shouldn't be able to operate the air blower motor speed. The blower motor may turn but turning the fan speed knob won't change a thing.
To remove the module, unplug the connecter, unscrew it from the blower housing and pull it. Do not forget to never operate the ventilation system when the module is out of the blower housing otherwise it will blow.
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