C5 X7 Blower Temperature Issues

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wheelson5
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C5 X7 Blower Temperature Issues

Post by wheelson5 »

wonder if I could piggy back on this thread?
I have a 2014 C5 estate. It is low spec but has a/c and air blower system operates through central controls next to radio/cd the temp range runs lo 14 ..........28 hi Not a temp gauge but 'comfort level' 22 is toasty and soon gets too warm but below that level it runs cold so cannot moderate heat to satisfactory level. Spotted a faulty cell and replaced battery but no change. Was heading down the replace blower motor resister so checked here earlier and completed the BSI reset but problem remains. Any suggestions as to problem/solution. thanks Wo5
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Re: C5 X7 Blower Temperature Issues

Post by GiveMeABreak »

We will need your VIN to determine exactly which system you have first of all.
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Marc
wheelson5
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Re: C5 X7 Blower Temperature Issues

Post by wheelson5 »

Thanks Marc,

VF7**************[VIN obfuscated, can be read by forum staff]

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GiveMeABreak
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Re: C5 X7 Blower Temperature Issues

Post by GiveMeABreak »

I've moved this to a separate thread as it is for a C5 with a different system.

So you have the Monozone system. This operates on the following basis:

The temperature required is obtained by mixing:
  • The hot air provided by the engine cooling system heater matrix
  • The cold air produced by a conventional air conditioning system by means of an evaporator
  • The air flow provided by a direct current motor (Air blower )
  • The distribution, the air intake and the mixing controlled by flaps controlled by stepper motors
The temperature settings are actually °C equivalents by default and this is the table of equivalents depending on the units you have it set for:
Different displays possible
Degrees Celsius (°C)Degrees Fahrenheit (°F)
LOLO
1456
1558
1660
1762
1864
18,565
1966
19,567
2068
20,569
2170
21,571
2272
22,573
2374
23,575
2476
2578
2680
2782
2884
HIHI
If you are getting a good source of heat, then I'm not sure that the heater matrix will be responsible - if this was blocked up, you wouldn't be getting much heat (if any) apart from the air heating resistance unit for the cabin, and that really only comes on at startup to help the cabin warm up and aid with demisting until the engine warms up.

What happens if you turn it up to full heat (when the car has warmed up) - if you are getting full-on heat, then I would say the heater matrix is dong its job. It may be possible that the air mixing motor is only partially operating.

If there was a fault with the temperature it would go into a backup mode - in this case the display would stick at either 21°C or 70°F (depending on your units). Any change on the dial won't have any effect. I can see from your picture that this is not the case though.

Apart from the air mixing stepper motor being at fault - another possibility is the actual A/C control panel itself. So what you could do before spending any cash it to check the connector - specifically the 26 way connector - channels 6, 7, 8 & 9, as these control the air mixing stepper motor. I would clean the connector pins with some electrical contact cleaner - has to be worth a shot.
Monozone.PNG
"a" 6-way black connector.
"b" 26-way yellow connector.

The automatic air conditioning control panel consists of 2 connectors:
  • 1 6-way black connector.
  • 1 26-way yellow connector.
26-way yellow Connector Channels
11 phase signal: Air intake stepper motor
23 phase signal: Air intake stepper motor
34 phase signal: Air intake stepper motor
4Supply: Air intake stepper motor
5Supply: Mixing stepper motor
63 phase signal: Mixing stepper motor
74 phase signal: Mixing stepper motor
81 phase signal: Mixing stepper motor
92 phase signal: Mixing stepper motor
104 phase signal: Distribution stepper motor
113 phase signal: Distribution stepper motor
122 phase signal: Distribution stepper motor
131 phase signal: Distribution stepper motor
142 phase signal: Air intake stepper motor
15-
16Signal: Blown air temperature sensor (Left hand )
17Earth: Evaporator temperature sensor
18Sensor signal: Evaporator temperature
19-
20-
21signal: Sunshine sensor
22Earth: Sunshine sensor
23Blower diagnostics connection
24Sensor earth: Blown air temperature (Left hand )
25Blower unit setting
26Supply: Distribution stepper motor
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Re: C5 X7 Blower Temperature Issues

Post by xantia_v6 »

I think that a diagnostic session with Diagbox would be a sensible step, it should be able to tell you what the controller is seeing from the various sensors, and how it is setting the actuators.

My suspicion is that the controller is trying to work around a sensor issue.
wheelson5
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Joined: 02 Dec 2019, 16:56
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Re: C5 X7 Blower Temperature Issues

Post by wheelson5 »

Thanks for that. And the extra details around the levels.
The 'comfort level' was a line from the dealer.
Hadn't thought to match degrees C and F but couldn't help thinking line was being spun when I asked for them to check.
Got a bit of fettling to do today.
Wo5
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