Air Condition issue, switch related? (1 Viewer)

[REZARF]

My 99 100 series blows ice cold all day long as long as the switch is fully turned to the COLD "Blue" side of the dial. If I even move the switch one click warmer it blows HOT, not just warm but HOT.

What gives? Bad switch? It's like I have Arctic or Sahara... no San Diego.

I don't even know where to begin.

 

[TheForger]

Sounds like you potentially have a faulty servo motor that controls the "gate" that opens and closes a certain amount based on how much you turn the temp dial. This is what mixes the hot and cold air to the correct temp you set along the temp dial. If this is the case then I might be able to help you since I had the same issue but it was about 1.5yrs ago so the details on the fix are kind of vague. But I believe the first step is to verify exactly what the issue is, because my suggestion could be the wrong one. I did experience the same symptoms of ice cold AC and then as I turned the dial more and more to the hot side it would very quickly begin putting out hotter than normal air at the setting it was on. Feel free to pm me if you want those details, it might take me a few days or so to look though all my records that I keep to find it but I will see if I can look either later tonight or in the morning.

 

[hoser]

There is a cabin temperature sensor, a tube behind the lower dash that ends up right below the ignition switch. If the tube disconnects it won't get an accurate cabin temperature reading. I imagine full "cold" ignores this sensor. But before that, I'd run the HVAC diagnostic test, using the HVAC buttons/controls. You'll have to do a search for it.

 

[REZARF]

Sounds like you potentially have a faulty servo motor that controls the "gate" that opens and closes a certain amount based on how much you turn the temp dial. This is what mixes the hot and cold air to the correct temp you set along the temp dial. If this is the case then I might be able to help you since I had the same issue but it was about 1.5yrs ago so the details on the fix are kind of vague. But I believe the first step is to verify exactly what the issue is, because my suggestion could be the wrong one. I did experience the same symptoms of ice cold AC and then as I turned the dial more and more to the hot side it would very quickly begin putting out hotter than normal air at the setting it was on. Feel free to pm me if you want those details, it might take me a few days or so to look though all my records that I keep to find it but I will see if I can look either later tonight or in the morning.

There is a cabin temperature sensor, a tube behind the lower dash that ends up right below the ignition switch. If the tube disconnects it won't get an accurate cabin temperature reading. I imagine full "cold" ignores this sensor. But before that, I'd run the HVAC diagnostic test, using the HVAC buttons/controls. You'll have to do a search for it.

Thanks guys, this gives me a starting point. I was messing with the dash about a month ago when this all started. I wonder if I failed to reattach that sensor or knocked it free while putting the dash back together. I was running a CB Coaxial.

 

[ih8everything]

I've had the same issue. The tube to the cabin air temp sensor under the steering wheel kept falling off. I used a zip tie to secure it on the sensor.

 

[REZARF]

So with winter here I am needing to really track this down. I dug into the dash and nothing was out of place. Is the tube the yellow ish one? I found one plug that didn't go anywhere but that isn't exactly uncommon on a 100.

Any other thoughts?