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I have a 2004 Saab 9-3 Linear with manual climate control. System was working fine up until last Sunday. It was cool out that day, maybe 55 degrees Fahrenheit and rainy. I went to turn the temperature knob to all the way cold (usually just leave it on that temp setting unless its really cold), and left the A/C off. The air coming out of the ALL vents was "room temperature" at the start of the drive, and then progressively got warmer and warmer. Once the engine got up to normal operating temperature, the temperature of the air coming out of the vents was very warm. I tried turning the A/C on to see if the air would cool a bit. It did, but only very slightly. Air was still coming out very warm.

I checked the A/C system, compressor turns on when button on dash is pressed, and aluminum refrigerant line leading from engine bay to cabin is very cold when A/C is on. Pressure in the system is where it should be..

It seems as if the heat is stuck on.. The system always used to blow the outside temperature into the car when the a/c was off and the temperature knob was all the way cold. Now it is always warmer than the outside temperature. Don't know if this is an electrical problem, or mechanical problem. Worried about taking it into the dealership just yet as money is tight. Any help is greatly appreciated! Thanks!

~Joe
 

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I have the exact say situaiton! Climate Control Only Blows hot only

Does anybody have any guidance about what might be happening here?


I have a 2004 Saab 9-3 Linear with manual climate control. System was working fine up until last Sunday. It was cool out that day, maybe 55 degrees Fahrenheit and rainy. I went to turn the temperature knob to all the way cold (usually just leave it on that temp setting unless its really cold), and left the A/C off. The air coming out of the ALL vents was "room temperature" at the start of the drive, and then progressively got warmer and warmer. Once the engine got up to normal operating temperature, the temperature of the air coming out of the vents was very warm. I tried turning the A/C on to see if the air would cool a bit. It did, but only very slightly. Air was still coming out very warm.

I checked the A/C system, compressor turns on when button on dash is pressed, and aluminum refrigerant line leading from engine bay to cabin is very cold when A/C is on. Pressure in the system is where it should be..

It seems as if the heat is stuck on.. The system always used to blow the outside temperature into the car when the a/c was off and the temperature knob was all the way cold. Now it is always warmer than the outside temperature. Don't know if this is an electrical problem, or mechanical problem. Worried about taking it into the dealership just yet as money is tight. Any help is greatly appreciated! Thanks!

~Joe
 

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I also had this problem, but the solution was simply to recharge the AC refrigerant. I used a kit I bought at an auto supply store (you can get cans with built-in gauges and a hose - hint, get one with a long hose), or take it to a shop that can check the charge for you.

If you do it yourself, you need access to the "low pressure port" which is low and behind the passenger-side (US) headlight. The one that's easier to get to is the high-pressure port.
 

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i had this problem and it was the external temp reading. I had the "---" for the outside temp and could never get the AC to turn on. Repaired the harness (which also fixed my fog lights), got an accurate external temp, and the AC worked again. Is your outside temp accurate?
 

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Thanks for the responses guys. I recently replaced the external temp sensor, and that seems to be working okay but my kid hit a curb that did some damage to the air deflector "shelf" under/behind the bumper so I wonder it there could be wire bundle damage that I didn't see. I will check that tomorrow.

On the HVAC unit replacement - I have a manual climate control so is the internal temperature control knob (or whatever is behind there) the possible culprit? If so, any tricks to gain access?

I will also check my A/C lines underneath to make sure there is no damage from the curb incident - - - then will attempt to refill the system.

Thanks again!
 

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Looking for more ideas

So I recharged the AC lines - the pressure was a bit low when I started, but is good now and the lines in the engine compartment get really cold. I dug around under the front end to ensure there were now issues with wires or tubing from the curb impact - there was none. The stepper motor on the driver side of the tunnel moves up and down with the temp setting is changed from hot to cold. With all this, the manual climate control still only blows out hot air. Not ambient temperature air - HOT air, regardless of temp setting and turning on AC has no affect.

Ideas please?

If this were an old school manual system where you pulled the knob and the wire moved the heater control valve, I would assume the wire was broken or the valve was faulty. What is the analogous diagnosis with the MCC system? Do the temp control knobs crap out? Do you have to replace the whole panel there? Is there a different stepper motor I should check?

It seems like it should be a simple fix, but I'm not sure how to proceed.
 

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Input and suggestions, PLEASE

My MCC problem is still with me. I bought a replacement in-dash MCC unit and the only thing I get is HOT air. Am I at the point that I need to take it in, or is there something obvious like an in-cabin temp sensor that ties everything together....??? My stepper motor on the left side of the console sounds like it's moving when commanded, but still not even ambient air circulation. Just Hot
 

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Seen this issue a few times... Took a long time for the dealer to figure it out but it was the ac evaporator. Replaced it and everything was fine.
 
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