2001 Sonata 4 cyl. heater problem.

We are experiencing a loss of heat after driving 45 minutes. The dealer
can't find the problem. Any similar experiences out there? Any
correlation between using the wipers and the heat problem.

 

Have you replaced the thermostat? That's the most common cause of
heating problems.

If your car has an electronic heater control module like the newer cars
do, that's also a likely culprit, especially if the heat works
initially, then malfunctions.

 

Improper coolant level, clogged heater core, thermostat stuck open. Many
possibilities. Has your dealer ever been able to experience the no heat
issue? If not, you may need to provide specific instructions as to how
they can duplicate. Does it tend to happen to you on a particular stretch
of road? What type of driving are you doing when it occurs? Try to give
as many details to your dealer as you can.

 

The heater cuts out in inclement weather while we are using the
windshield wipers.

 

Do you mean that the blower stops or that the air becomes cold?

There's no link between the heat and the wipers, but it's theoretically
possible there's an electrical issue affecting the wipers and blower.

 

The blower works fine but it blows cold.

 

I'm pretty much at a loss. There's just about zero connection between the
wipers and heat. It would seem that if the dealer can make it happen,
they should be able to figure it out while it's happening. Sorry I don't
have more to offer.

 

If it's blowing cold air, it would seem that it would have to be a
problem with the heater control module. Perhaps it's not be reading the
setting on the temp dial and consequently it's not opening the valve on
the heater core. I don't know how that would be related to the wipers
other than they're both electrical issues.

 

I haven't yet seen a schematic for a Hyundai, but my Chryco minivans
have several common ground points where several circuits come to a
common ground. If one of these connections gets corroded between the
wire terminals and the chassis or comes loose from the chassis, one
circuit will be trying to use the other circuit as the ground path.
This can cause seemingly unrelated circuits to "crosstalk" and have
weird things happen. Maybe Hyunday doesn't use such a wiring
architecture, but it almost sounds like this.


Matt

 

If you've got the auto controls, what Brian describes is possible. If
they're manual, I believe the heater door is vacuum operated.

 

Does the Sonata use similar controls to those in the Elantra? From what
I understand, the '01 and up Elantras all have electronic controls,
although they changed somewhat in '04.

 

I'm not sure whether they're the same. In fact, you're making me question
whether I was correct on the vacuum operation in my earlier post. The
manual climate controls are so trouble-free, I'm not sure if I've ever had
one of the newer ones out. I suppose the way to check is to go to the
schematics and have a look around.