Rising temperature when running air conditioner

[Matt Verner]

It is about 70degrees outside. When the air conditioning is on and
the car is moving, everything is fine. However, when I stop for
traffic, the temperature guage rises pretty quickly to the top, and
the AC starts blowing warm air. Once, I start moving again, things
seem fine. This started a few weeks ago.

Anyone have an idea of what's wrong.

Thanks.
Matt

 

[Victor Roberts]

It is about 70degrees outside. When the air conditioning is on and
the car is moving, everything is fine. However, when I stop for
traffic, the temperature guage rises pretty quickly to the top, and
the AC starts blowing warm air. Once, I start moving again, things
seem fine. This started a few weeks ago.

Anyone have an idea of what's wrong.

In my '97 Outback and most modern cars there is an electric fan that
cools the radiator and AC condenser, but it only operates when you are
not moving. During normal travel the air flow through the radiator and
condenser is sufficient to provide cooling without the fan, so it is
shut down to save energy.

Either the thermostat that controls the fan is broken, or the fan is
broken, or a fuse is blown or a wire is disconnected.

 

[Tony Hwang]

Hi,
Maybe evaporator fan is not coming on?
Tony

 

[Toe]

I posted about the same issue about a week ago....stilll hopeing for a
good answer...besides the obvious which is bring it in for service...

 

[Victor Roberts]

I posted about the same issue about a week ago....stilll hopeing for a
good answer...besides the obvious which is bring it in for service...

What is a "good" answer. Two of us have suggested the same thing:
namely that the electrically operated fan used for the radiator and
A/C condenser is not operating properly. Have to checked to see if the
fan is coming on when you are standing still with the A/C operating?

 

[pheasant]

What is a "good" answer.

Something that is free, and doesn't require any time or
effort.

Mark

 

[Victor Roberts]

Interesting. I'd wondered whether or not the fans were cycling with the AC compressor when
cruising. But frankly I wasn't as concerned about energy savings as much as I was concerned about
the life of the fan motors. :^) -Danny

No, they don't cycle with the compressor. And, in some cars they can
turn on AFTER the engine has been turned off (as the radiator
temperature rises after you stop moving), so watch out for your hands
if you play in the engine compartment.

 

[Danny Russell]

My 2000 Forester cycles when the air cond compressor is on. Eddie

Ed, my question was whether the fans are over-ridden by output from the vehicle speed sensor. In
other words, there'd be no need to have the fans cycling with the compressor when the car's cruising
down the highway. -Danny

 

[Victor Roberts]

Ed, my question was whether the fans are over-ridden by output from the vehicle speed sensor. In
other words, there'd be no need to have the fans cycling with the compressor when the car's cruising
down the highway. -Danny

The temperature sensor used to turn on some A/C condenser fans serves
this same purpose. I don't know of any that have a speed sensor. A
temperature sensor is both more direct and, I would assume, less
expensive, since it does not require connection to any other systems.

 

[Tony Hwang]

Hi,
Whether car is moving or not, if it gets hot, fan gotta come on and even
run few minutes to cool off when engine is shut off.
Tony