Heater not blowing as hot as usual - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 General Tech Q&A > General

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  #1  
Old 12-15-2012, 08:22 PM
BanditGTP BanditGTP is offline
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2003 GMC Envoy SLT XL
Light Pewter Metallic 4.2L I6 AWD
Join Date: Oct 2010
Location: Central NJ
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Heater not blowing as hot as usual

Does anyone know what would be causing the heater to not blow hot air like I'm accustomed to? My truck is getting up to the correct operating temp just as quick as usual but for some reason the heat just never gets as hot as usual. Is there a temperature "blend" door or valve that would control how hot the air would be. Its taking longer and longer in the morning to get the frost off the windshield.
Thanks for any help or advice.
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  #2  
Old 12-15-2012, 11:34 PM
daduafu daduafu is offline
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2002 Chevy TrailBlazer LT
Imperial Blue Metallic 4.2L I6 4X4
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Smile

there are temperature actuators for both driver and passenger, as well as a mode actuator that directs air to selected vents. there is also a defrost actuator. if a temp actuator is bad, that side will be stuck at the temperature setting it was at when it broke, while the other side can be varied from hot to cold. i believe the defrost actuator just opens and closes, depending if selected mode includes defrost. there is a reset procedure for the climate control that calibrates the actuators. if none of that pans out it could possibly be a problem with the heater core, which I have no experience with.
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  #3  
Old 12-16-2012, 07:19 AM
BanditGTP BanditGTP is offline
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2003 GMC Envoy SLT XL
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I'll take a ok to see if the passenger side twp changes at all. Do you happen to know how to do the reset procedure for the actuators?
Thanks
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  #4  
Old 12-16-2012, 10:42 AM
daduafu daduafu is offline
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2002 Chevy TrailBlazer LT
Imperial Blue Metallic 4.2L I6 4X4
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climate control reset

pull fuse #36 under driver side rear seat for 30 seconds with the ignition off. reinstall fuse and turn ignition switch to run position and DON'T TOUCH ANY CONTROLS for two minutes. you should be able to hear your actuators cycling through their range. a clicking sound is often heard in the dash if one of the actuators is broke. if you get full heat from one side or the other, it's a temp actuator. if full heat never happens, either side, I'd look upstream, which is the heater core. I'm not even sure where the core is within the dash. try searching on this site, or from google, which usually finds stuff on trailvoy I cant.
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  #5  
Old 12-16-2012, 11:38 AM
BanditGTP BanditGTP is offline
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2003 GMC Envoy SLT XL
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Thanks for the helpful tips. I'll check it out today and hopefully it'll be a quick fix. I'm definitely not looking for more projects to add on my "to do" list.
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  #6  
Old 12-16-2012, 01:17 PM
Loverotties Loverotties is online now
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Quote:
Originally Posted by daduafu View Post
pull fuse #36 under driver side rear seat for 30 seconds with the ignition off. reinstall fuse and turn ignition switch to run position and DON'T TOUCH ANY CONTROLS for two minutes. you should be able to hear your actuators cycling through their range. a clicking sound is often heard in the dash if one of the actuators is broke. if you get full heat from one side or the other, it's a temp actuator. if full heat never happens, either side, I'd look upstream, which is the heater core. I'm not even sure where the core is within the dash. try searching on this site, or from google, which usually finds stuff on trailvoy I cant.
When you turn it to run,where should all the controls be?
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  #7  
Old 12-16-2012, 11:00 PM
daduafu daduafu is offline
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2002 Chevy TrailBlazer LT
Imperial Blue Metallic 4.2L I6 4X4
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Location: cincinnati, oh
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reset

Loverotties Quote:
Originally Posted by daduafu
pull fuse #36 under driver side rear seat for 30 seconds with the ignition off. reinstall fuse and turn ignition switch to run position and DON'T TOUCH ANY CONTROLS for two minutes. you should be able to hear your actuators cycling through their range. a clicking sound is often heard in the dash if one of the actuators is broke. if you get full heat from one side or the other, it's a temp actuator. if full heat never happens, either side, I'd look upstream, which is the heater core. I'm not even sure where the core is within the dash. try searching on this site, or from google, which usually finds stuff on trailvoy I cant.

When you turn it to run,where should all the controls be?

I don't think it matters, I do it with climate control turned off. It turns itself on and runs through its' procedure
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  #8  
Old 12-17-2012, 12:03 AM
Loverotties Loverotties is online now
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Thanks! good to know!
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  #9  
Old 01-01-2013, 08:30 PM
BanditGTP BanditGTP is offline
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2003 GMC Envoy SLT XL
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I tried the fuse trick but of course it didn't do the trick. The temperature seems to be the same on both the driver and passenger side so I son't think this was the problem but thanks for the info.

I haven't really dug into it too much since it my wife's truck and she hasn't been complaining too much about it. I did notice when I drove it the other day that the temperature gauge barely went above 1/4 so I hooked up my scanner and it looks like the hottest reading I ever saw was 162F. It never went higher even with jumping on and off the highway and driving 70mph. If I understand correctly, if my truck has a 180F thermostat, shouldn't the temp get up to 180F during warm up and then level off and stay around 180F.

I'm wondering if my thermostat might be stuck open and that is why the truck is taking so long to warm up and then also never really reaches the correct operating temperature. Does this sound like a possibility? (granted the temperature outside lately has been in the 40's but I would think the temperature should still go up the the 180 range before the thermostat opens up.)

Any input would be greatly appreciated.
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  #10  
Old 01-01-2013, 09:07 PM
Loverotties Loverotties is online now
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2002 Chevy TrailBlazer LTZ
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Yes it sound like it's bad(they fail open) which runs richer which uses more gas and can clog that cat.also sencor could be bad,but do both!
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