405 - Heater

tomic

Member
Fellow Frogger
Joined
Jan 13, 2004
Messages
24
Location
ACT
The climate/heater control has been playing up for a little while now. It hasn't been much of an issue till now. As of Sunday night, I've had nil heating and anyone who knows Canberra would well know how pleasant it has been this week. I've got nil idea where to start looking. Suggestions as to what the problem might be?

Cheers,
-dave.
 

OddFireV6

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Fellow Frogger
Joined
Mar 31, 2004
Messages
176
Location
Melbourne
There is a little electric motor and gearbox that drives a flap up and down between the heater core and evaporator. This unit is controlled by a control box that resides at the forward lowermost part of the central heater unit. The most common failures are failure in the gear box where the plastic gears strip and failure of the control unit where the transistors that drive the motor fail. I have simply replaced all the transistors on these units and got the system working again. They use 4 * BC337 and 2 * BC 327 transistors ,these are common and garden and are cheap.

In respect of the gear box if you do a search on my posts you will find some words where I fixed my heater flap gear box using little gears from my Tamiya 10th scale remote control car.

I have assumed that you have checked the heater core is getting water circulation and that its getting hot.
 

Decca

Active member
Fellow Frogger
Joined
Jul 10, 2004
Messages
936
Location
Canberra
Tomic
The motor mechanism OddfireV6 is referring to is , I think , the recirculating flap and they fail regularly. The same unit I believe is in the 406 and suffers the same fate.
Check the water flow as OddfireV6 suggested, feel the pipes feeding the heater on the engine side of the bulkhead. Check there is plenty of coolant.
You can check by slightly opening a plastic cap on the thermostat housing to see if a little bit of coolant dribbles out.
My 450 S2 SRI needs regular topping up, albeit only a cupful every month or so, and I live in Canberra.
Regards Decca
 
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