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Discussion Starter #1 (Edited)
The Problem
My fiancée's Peugeot 407 SW 1.6 (2005) has a problem whereby the blower/vents only provide luke warm air. It started after the car had been left parked unused during the cold snap at the end of last year.

Attempts to adjust the temperature are futile as far as the vents are concerned, despite the dash indicating a different temperature number.

A major observation is that a lot of hot air does come into the passenger side footwell from the kind of area where the motors operate the vents. Please note that this air isn't coming through the traditional footwell vent.

I have spent hours searching online and taken on board numerous ideas from 407 owners with similar problems. Most people seem to complain of one side being at fault but on my car it is all vents affected.

Here are the actions I have taken so far:

1) Confirmed that the heater core/ matrix has hot pipes when the engine has been running for a while (looks like this)

2) Confirmed that the engine temperature is as expected when the car is heating up, and has been running for a while.

3) Checked the pollen filter, looks fine. Have hoovered and replaced it.

4) Removed the directional vents in the central dash area to reveal the blue and grey vents below. By adjusting the fan speed I can see these vents turn on and off (and stages between) without problem.

5) Run the actuator tests for 'driver side mixing motor' and 'passenger side distribution motor' using Peugeot Planet. As per 4, I could see the vents turning. For the other test I could hear similar sounds but can't see below the blue and grey flaps to confirm the lower flaps are moving. Putting my finger on the motor itself I'm fairly sure it is turning okay.
From my research I think the 407 mixes air using the set of lower flaps? Can anyone confirm/deconfirm this?

6) Checked for fault codes on Peugeot Planet. It reveals two air con ECU faults:
F734 - Blower motor diagnostics signal acquisition fault
F702 Passenger compartment Humidity sensor fault - which I believe is unrelated...

I have Peugeot ServiceBox but it doesn't shed any light on F734...

Other faults (that I suspect are unrelated) are:
P0238 Intermittent Fault. Turbo pressure signal high turbo pressure sensor raw signal
P1351 Permanent Fault. Pre/post heating relay circuit relay controlled and spark plug not supplied.
P1403 Intermittent fault. Additional heating circuit 1 short circuit to earth, short circuit to positive, open circuit or actuator malfunction.
P1404 Intermittent fault. Additional heating circuit 2 short circuit to earth, short circuit to positive, open circuit or actuator malfunction.

So for those interested the last characters of the VIN are 20050452. I'm keeping my fingers crossed someone on this forum has either come across this, or knows what to check/do! Just trying to avoid having to remove the entire dash :eek:
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