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Discussion Starter #1
went to warm up the slobalt and shes blowing ice cold air! thermostat is fine, coolant temps are normal and the engine heats up just fine. my heater core is not leaking and flowing just fine (tested by feeling the hoses running to it which were both hot). fuses are fine, and im stuck. could my hvac controls be fried? maybe the actuator which switches the airflow from hot to cold is stuck or broken? i dont know where to start! and its very cold out. if any of you guys have any ideas or pointers throw em my way!
 

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Maybe your heater is frozen. lol

---------- Post added at 05:18 PM ---------- Previous post was at 05:17 PM ----------

Did you check the 2 fuses?
 

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Do you hear any trap door movement when you turn the knob?
 

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Discussion Starter #5
Would it make the noise if I have the air off? My car is rather loud and I wouldn't be able to tell with the added noise
 

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Engine doesn't need to run to check trap doors. Just turn ignition on and turn knob. Trap doors should follow the position selected.
 

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Looks like a trip to the dealer is in view....
 

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Discussion Starter #9
not an option, im between jobs and my car is very modified so they wont warranty anything. time to break out the gloves and hat
 

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I had to replace the HVAC control unit in my Cobalt. it fried and first non of the AC, Rear defrost buttons would light. the control later then would not respond to heat or vent controls. I went on E-Bay got one for 50 bucks as opposed too the 300 the dealer wanted and installed it myself in about 20 minutes
 

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Heat/Cold Blend Door

Pull the panel off right drivers side footwell. It comes off easily as it just uses spring clips to secure. There are two similar black housings with wires running to them, they are the servos for your hvac controls. The bottom one mixes heat and cold air. With the ignition on, turn the heat/cold rotary knob and see if the servo is working. If it is not, you have a servo issue: bad servo, blown fuse, wiring issue. If it is working, remove the two screws holding it in place and see if the shaft to the blend door is broken. If the shaft is broken, it will be major $$ for the dealer to fix it. Mine was broken and I didn't want to spend over a grand to have the dealer repair it. I used a piece of brass bushing with the correct i.d. to use as a coupling. Use some two part epoxy, the coupling bushing and glue the thing together in the correct position. My repair works great and it cost about ten bucks versus the $1200 the dealer wanted. Look at my post for the heater blend door repair in this section of the forum. I've added a couple pictures. They are not great but should give you an idea of what to do.

http://www.yourcobalt.com/forums/problems-service/31118-temperature-mixing-door-2008-cobalt-sport.html
 

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Discussion Starter #15
I owe you!!!! I popped off the servo and bam, it was broken right in two. I used plastic weld epoxy to glue it back on, and molded quick plastic around it for more strength. Works perfectly and only took a couple hours, including a trip to autozone and a lunch break haha. You're a life saver
 

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Glad to hear you figured it out
 

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This should be a how to somewhere so others can benefit.
 
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