Following recommendations on an earlier thread about fogging windows, I have opted to use my auto function whenever possible. The problem is I really don't get heat, even when cranked all the way to highest setting. I know it's not the dreaded control valve problem because if I choose manual heat it blows hot fine (albeit with windows soon fogging), it's just as if the auto function has no idea what the temp in the cabin is and just runs the AC. So currently I can have warmth and fog or clear and cold.

Any suggestions on where to start looking?

 

Either clean/replace or read the sensors.

 

Start with the rectangular sensor in the dash near the steering column. Remove the grille - it just pops out - and clean the sensor behind it. There are 2 further sensors beneath the dash, they need checking out as well. Try setting the climate to dual and then adjusting the levels side to side one at a time. It will probably be something fairly straightforward.

 

How do you "read" them?

 

Software. Dealer-type such as IDS/SDD

You can use a meter but it's a lot easier with software.

 

All the evaporator sensors (there are 3 not 2) are the same. You can pull them out and check the resistance. They should all read the same. If one reads different swap it out.

The good thing is the sensors are not very expensive and of course they are identical to the Lincoln LS ones which means it's a Ford part.

Now getting to them and getting them out is a bit hard because they are up beside the evaporator so look at the gas pedal and go straight up and to the right. They are white plastic and you need to unplug the wire plug first before removing them. Same position on the passenger side. We have several good threads with pictures showing where they are.

It would be worth your time to find them. The part numbers for the temperature sensor is listed too.

Be sure and clean the in cabin temperature sensor as suggested above. Mine was dirty and it did help cleaning it. Be careful and use a Q-tip wet with solvent.

I did not see where you have checked that the car is still draining water out the A/C drain? Do you have a good sized water puddle under the car?

Any chance that it might be plugged up?

Is your outside temperature reading correctly?

I have attached some pictures to help out. Note the Lincoln LS drivers side has two temperature sensors (yellow arrows) and the passenger side has one. Again the same as the S Type.

I have also attached the sensor picture so you can tell what it looks like.
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What comes out of the vents while in auto mode when the temp setting is cranked to maximum, 32* I think?

What is indicated on the control panel?

 

It goes to 29 max. Very hard to tell if I get a puddle living in a rainforest. But I've been under the car and there certainly isn't a drain hose hanging down below the AC unit. I don't know where they route it or if its broke off but I can't see an end.

I'm going to try the cleaning tip then go for resistance check if that doesn't help. I'm just fortunate to live where I do where the winter climate is so mild.

 

Sorry, I meant the air vents inside the car, not the condensation drains underneath.

While in auto mode and the temp is set to 29, do you get warm air coming out the vents inside the car and does the fan go to full speed?

 

The only time that happens is if I go beyond 29, then it changes to "Hi" and auto is no longer illuminated. But even then I have to turn off the ac

 

I guess I'm not phrasing my question clearly enough.

If I understand your answers, you get NO heat whatsoever with the controls set to 29* and the system in 'auto'?

 

Sorry that I'm not understanding: it's very hard to say if there's "no" heat at all; all I can really feel is the AC air blowing over the dash from the windshield vents. I don't feel warm air flowing from anywhere else. If there is, it's pretty minor compared to the cold air flow. If I want to feel warm air flowing I have to shut off the AC.

 

I think there's something else going on. The air should not be blowing just out of the defroster vents and nowhere else unless the defrost function is manually selected.

 

It's hard to say; I suspect that we just notice the defrost as it's so cool. The fan speed is pretty low and its hard to tell if much air is coming out of the rest of the vents. In manual mode is does correctly select various vents and temperatures. I suppose its possible the coolant valves are acting up.

 

This is not normal either. Again, if in auto mode, I were to increase the temp setting on my car to (say) 29* on a cool day, the fan speed would instantly increase to maximum and remain at that speed until the car interior is close to the desired temperature. The air coming out of the vents would be very warm/hot.

Yours doesn't appear to operate that way. Not sure what that's symptomatic of.

 

Good to know. considering we know that controls work, it seems the computer isn't telling them what to do. If the inputs are messed up due to faulty sensors that might account for it. When I get a moment I'll pull them and take some measurements.