Running hot with the AC on

Hi

I've noticed in the last few days that when using the AC in my 406 the water
temp goes very high, up to nearly 100c after a while stuck in traffic. Is
this just due to the hot weather we are having or could there be something
else wrong.

Fan seems to working ok as I can hear it spinning and coolant is ok. I've
never noticed the temperature going so high before with the AC on...

 

Sounds about right, mine hits 100c when standing still, then cools down to
90c, then back up and so forth.

--


Kind Regards
Cheater

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Maybe the water temperature gauge on the 406 is very sensitive? IIRC the
gauge on the Corsa is also very sensitive, the needle movement is very
noticeable as engine load conditions change. On most cars that I have owned,
the needle just sits in the middle and then creeps up in traffic queues on a
hot day.

Here's another theory: -

On all the A/C cars that I have owned, the A/C condenser radiator is mounted
in front of the engine's water radiator. If you have the A/C on then the
condenser radiator is going to get warm and warm air will then be
pulled/pushed onto the water radiator. With the A/C off the air moving over
the water radiator will be cooler and the water radiator will therefore be
more effective.

With the A/C on the engine is also going to have to work a little harder to
drive the compressor as well, which in turn will generate more heat.

Having said this, I haven't noticed the water temperature rising
siginificantly when I use the A/C my cars... (Astra/Fiesta/Focus).

If it's really bothering you then try turning the heater controls in your
car to the hottest setting. The heater matrix in the car will act as an
additional water radiator. The engine will cool down but you will be
*really* hot and bothered.

 

Under these conditions your fans (there are two) should switch to hi speed. If
this is not happening, suspect the three relays mounted near the fans behind the
grille. Between them, they switch the fan motors from in series to parallel to
change speeds.

 

That is good advice!

My old 406 2.0 had that problem. The fans were staying on slow so in traffic
the temp quickly raised.

One time in a traffic jam on a hot day the temp went to 110 + and the stop
light came on.

Took it to garage and it was the fan speed control module located near the
radiator