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post #1 of 6 (permalink) Old 01-01-2013, 07:12 PM Thread Starter
 
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Angry hvac problems

I purchased my 2003 duramax last spring and don't drive it on a regular basis so this week was the first time I really needed the heater. It seems as if it was blowing air conditioned air into the cab. I have the automatic dual heat system.
I turned the heater off to stop the cold air flow.
Tonight I ran the truck to warm up the engine and tried to get some heat. The only way I could get any heat was to put the temp at 90 degrees. The air conditioner seemed to work fine but I had trouble getting it to stop blowing cold air after I turned off the air conditioning.
I have heard that this might mean a bad actuator. I think there are two different actuators. I also wonder if the unit in the dash with the controls could be bad.
I tried laying on the floor and watching the actuator above the accelerator to see if it moved as I dialed the temp up and down and could not see any movement from the gear spline. Is there another actuator that is behind the one I am seeing? The part # on it is 52495593. Thanks for any advice.

2003 DURAMAX 3500 SLE CREW CAB DULEY 4X4 BOSE RADIO
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post #2 of 6 (permalink) Old 01-01-2013, 08:54 PM Thread Starter
 
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Originally Posted by 1998 diesel View Post
I purchased my 2003 duramax last spring and don't drive it on a regular basis so this week was the first time I really needed the heater. It seems as if it was blowing air conditioned air into the cab. I have the automatic dual heat system.
I turned the heater off to stop the cold air flow.
Tonight I ran the truck to warm up the engine and tried to get some heat. The only way I could get any heat was to put the temp at 90 degrees. The air conditioner seemed to work fine but I had trouble getting it to stop blowing cold air after I turned off the air conditioning.
I have heard that this might mean a bad actuator. I think there are two different actuators. I also wonder if the unit in the dash with the controls could be bad.
I tried laying on the floor and watching the actuator above the accelerator to see if it moved as I dialed the temp up and down and could not see any movement from the gear spline. Is there another actuator that is behind the one I am seeing? The part # on it is 52495593. Thanks for any advice.
tonight I removed the HVAC fuse for 5 minutes and then replaced it and ran the truck for 5 minutes. very cold air was coming out of the vents while the temp was set at 72. I still had to run the temp up to 90 to get warm air. But I could get warm air. Something isn't right?

2003 DURAMAX 3500 SLE CREW CAB DULEY 4X4 BOSE RADIO
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post #3 of 6 (permalink) Old 01-01-2013, 09:12 PM
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It has 2 actuators for temp. Driverside is on the very bottom of the case, and pass side is in top of case, behind and to the left of glove box (can't replace that one without a bunch of work) if they are blowing the same temp out both sides, it's either out of calibration or the core is restricted/gelled up. I would make sure both heater hoses are warm/hot first. If not flush the core. If thats not it, unhook the batts, then rehook, turn key on, don't touch anything for at least 30 seconds, turn key off, then start the truck and see what happens. Control head or both actuators could be bad, but not likely.

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post #4 of 6 (permalink) Old 01-02-2013, 10:37 AM Thread Starter
 
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Originally Posted by KensAuto View Post
It has 2 actuators for temp. Driverside is on the very bottom of the case, and pass side is in top of case, behind and to the left of glove box (can't replace that one without a bunch of work) if they are blowing the same temp out both sides, it's either out of calibration or the core is restricted/gelled up. I would make sure both heater hoses are warm/hot first. If not flush the core. If thats not it, unhook the batts, then rehook, turn key on, don't touch anything for at least 30 seconds, turn key off, then start the truck and see what happens. Control head or both actuators could be bad, but not likely.
The two heater lines are just warm to the touch after running the engine about 5 minutes. To flush the core do I unhook the lines where the rubber hose connects to the metal line? Which way do I flush the line, left line in or out? Probably with low water pressure?

2003 DURAMAX 3500 SLE CREW CAB DULEY 4X4 BOSE RADIO
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post #5 of 6 (permalink) Old 01-02-2013, 10:52 AM
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You have to drive the truck for a bit to get any heat out of it. 5 mins of idling barely does anything.

Take it for a 20 minute joy ride and work it a little so the engine is good and warm. Then see how the controls function. Diesels are cold blooded. They don't get warm instantly like a Gasser does.

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post #6 of 6 (permalink) Old 01-02-2013, 11:35 AM
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what he said^^^...especially if your'e in a cold location.

2012 GMC 2500 SLT 4x4
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