99 C43 Heat only blows hot on HI
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Joined: Jun 2014
Posts: 199
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W202 w/ a 5.4L V8
99 C43 Heat only blows hot on HI
Hi guys/gals, my c43 isn't blowing hot air unless it's set on hi. I can hear the doors actuating behind the dash so I assume the blend doors are good. The water pump was recently replaced and the car doesn't overheat. The thermostat seems to work properly (once the car reaches operating temp, the coolant cycles through the block and back to the radiator). The exterior temp sensor has never worked but all other temp sensors work. I don't think the exterior temp sensor is a factor because the car would regulate temperature on warm days (a/c wouldn't blow super cold unless I set the temp very low and the car maintained the temp set on my HVAC display). I did the diagnostic through the display and the only fault code is "227" the outside air temp sensor. What are your suggestions or where should I start looking? It's very frustrating to drive around with the a/c blowing in winter 
TIA
TIA
Last edited by Alex33; Nov 23, 2014 at 02:03 AM. Reason: added info
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Joined: Feb 2012
Posts: 85
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From: Beaverton, OR
2002 C32
Mine started doing that recently, apparently the hvac control heads go bad on these cars and the dealer recommended replacing it. $1400 new from the dealer, or $200+ for a used one. I just had the blower motor and HVAC resistor replaced this month too since they were also bad. $1000 to replace both of them with new OEM lol. At least they work now!
Thread Starter
Member
Joined: Jun 2014
Posts: 199
Likes: 10
W202 w/ a 5.4L V8
Mine started doing that recently, apparently the hvac control heads go bad on these cars and the dealer recommended replacing it. $1400 new from the dealer, or $200+ for a used one. I just had the blower motor and HVAC resistor replaced this month too since they were also bad. $1000 to replace both of them with new OEM lol. At least they work now!
Member
Joined: Feb 2012
Posts: 85
Likes: 0
From: Beaverton, OR
2002 C32
They hooked the computer up to it and they said that the values it was outputting weren't what they were supposed to be. I guess when you push the buttons it outputs a signal and my temp control wheel wasn't outputting anything when they moved it.
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Thread Starter
Member
Joined: Jun 2014
Posts: 199
Likes: 10
W202 w/ a 5.4L V8
I know it's been a while but wanted to bring this up to the top with updates. It turns out the issue was my outside temp sensor, as much as I refused to believe it. I plugged in the new one I purchased when I bought the car and the HVAC system works as it should. Now the only issue is the common LCD display issue.
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