Climate control does not control?

[ofpiste]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

[KevinMac]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

The cabin temp sensor may be at fault.

[RF5BPilot]

Actually, I took my '03 006 to the dealer about this last week. If I set the temp to 64F, the cabin still warms up well past that.

The service writer said that the system bases how much heat it adds on the temp of the incoming air, so it might well heat up beyond the temp set. If it seems warm, turn it off or open a window.

This didn't make sense to me. Why have a temp setting if the system essentially ignores it?

[ofpiste]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

The cabin temp sensor may be at fault.

Thanks KM....would you happen to know off hand where this sensor is located?

Dennis

[1schoir]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

The cabin temp sensor may be at fault.

Thanks KM....would you happen to know off hand where this sensor is located?

Dennis

Dennis:

In a Boxster, The sensor for the cabin interior temperature is located inside (behind) the right dashboard vent. It is part of a small fan assembly that serves to blow interior air over the sensor.

It is probably in the same location in your C4.

Regards, Maurice.

[john in lb]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

As discussed above, the sensor is on the right side of the dash. It is a thermocouple with a small fan to blow over it. It could be the thermocouple or the fan (or anything which prevents cabin air from blowing over the thermocouple.) Unfortunately, a thermocouple is something that does not fail very often... so, if that's not the problem, then you have to consider the control unit or the thermocouple located in the front of the car (the one that reports the outside temperature on your dashboard).

This brings me to the second point... the thermocouple located in the bumper is part of the climate control system, to the extent that it helps decide how much extra heat or cooling to add (based on the difference between the incoming fresh air and the desired temperature). So the service rep was kind of right - but not being clear. The end result is the climate control uses both sensors to maintain cabin temperature.

Loren might be able to shed more light as to how to diagnose the problem further.

[wwest]

Have a 2k C4 Cab that recently has been acting up. When you set the climate contol to auto and set the temp at..say70 F it seems to heat the cabin well past this temp. I have never had a problem with this in the past and have thought it was one of the best climate control units out there.

Any suggestions?

Thanks

As discussed above, the sensor is on the right side of the dash. It is a thermocouple with a small fan to blow over it. It could be the thermocouple or the fan (or anything which prevents cabin air from blowing over the thermocouple.) Unfortunately, a thermocouple is something that does not fail very often... so, if that's not the problem, then you have to consider the control unit or the thermocouple located in the front of the car (the one that reports the outside temperature on your dashboard).

This brings me to the second point... the thermocouple located in the bumper is part of the climate control system, to the extent that it helps decide how much extra heat or cooling to add (based on the difference between the incoming fresh air and the desired temperature). So the service rep was kind of right - but not being clear. The end result is the climate control uses both sensors to maintain cabin temperature.

Loren might be able to shed more light as to how to diagnose the problem further.

Both, IAT & OAT are thermistors, resistors that change resistance with temperature...colder = higher resistance.

An open OAT (bumper sensor) would indicate EXTREME COLD outside and the system might compensate by increasing the cabin air OUTFLOW temperature beyond your comfort level, but not likely very much above your setpoint, on the average. An open OAT sensor on the other hand would result in the cabin temperature rising higher and higher.

[Richard Hamilton]

There are two more temperature sensors that haven't been mentioned so far. One is on the footwell blower outlet, and the other is on the air inlet.

I would have thought you could eliminate the OAT sensor (in the front PU) if the OBC temperature display is reading correctly.

[Richard Hamilton]

I'm not sure if your aircon panel will do this, but on early cars you could access the climate control diagnostics on the unit. I've attached some instructions I stole from an Audi forum (Audi manufacture the CC unit). If it works on your car, you should be able to see the temperature sensor outputs.

Climate_Diaagnostics.pdf

[ofpiste]

As always..Renntech shines!

You guys are such a wealth of information, can always trust that no matter how small or complicated the question you will have the answers!

Thanks!