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2005 chevy trailblazer_ls
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Discussion Starter #1
i have a 2005 chevy trailblazer LS. it has been rock-solid in its 96000 miles. but in the last 6 or 8 months i have been having a slight issue with it. hopefully someone has some insights...

it started in the winter. i would put the heat/defogger on and it would take a verrrry long time to get hot. and when it did put out heat, it was very weak. when i would switch the location for where to blow the heat, nothing changed (from foot well to defogger to front-blower). i did some research, found that that the blower actuator probably needed to be re-calibrated. i followed instructions i found online, and i pulled the fuse under the back seat, waited, plugged it back in, and great, my blowers change zones now, but i still got very little heat out of it.

winter ended, summer came, and now i am not getting any AC out of the thing. there is some resistor under the dash on the passengers side of the car that senses the blower, and i replaced that. made no difference, though the old one was covered in rust. i thought it might be the AC Clutch relay, so under the hood i pulled the relay, swapped it with the windshield washer relay (they are the same), but still no AC. and the windshield washer still works, so i am pretty confident it is not that.

it could be out of freon, but i don't know how that would effect the heat in the winter. i suspect a bad fuse or something, but i have checked all the fuses in the book that involve anything to do with climate control, and they all look fine (i should probably check with a meter, but i haven't yet).

i'm stuck here, i have no idea what to check next other than taking it for an AC Recharge... and i want to avoid that expense if i have to. anyone have any ideas?
 

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2004 gmc envoy_sle_xl
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1,239 Posts
I assume you have the Auto HVAC system, with the digital display, since you have the LT model.
To have little or no heat or cooling is very unusual. Does your fan speed change with the panel control? Is the exterior temperature displayed correct?
There may also be an obstruction within the unit's plenum.

Suggest posting your problem at G M T N a t i o n . c o m / f o r u m s (no spaces), most of the experts from here went there.
 

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2005 chevy trailblazer_ls
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Discussion Starter #3
I assume you have the Auto HVAC system, with the digital display, since you have the LT model.
To have little or no heat or cooling is very unusual. Does your fan speed change with the panel control? Is the exterior temperature displayed correct?
There may also be an obstruction within the unit's plenum.

Suggest posting your problem at G M T N a t i o n . c o m / f o r u m s (no spaces), most of the experts from here went there.
thanks for the suggestion. actually, my profile is wrong... i selected LT when it is an LS. it has the automatic control with rear heat and all, but not digital. so it has the manual controls, but it separates driver and passenger side into 2 individual zones. i don't think it is the most basic heating package, but it isn't the most advanced either. so no external temperature display

the speed control changes the speed of the blower, but the strange thing is that it doesn't seem to blow as hard as it once did. but it does blow. maybe it is just psychological because i'm not getting any temperature change out of it.

also, i would think that if there was an obstruction, i would get some bleed through of either heat or cold when the AC was one. when the temperature is set to the lowest setting, i get the same temperature coming out of the vent whether i have the AC on or not. and that is actually room-temperature. with the AC, if i set it to the middle (not hot or not cold), i actually get warm air coming out of the vent. and now that it is summer, if i set the heat to on, i get a lot of heat out of the vent.

i'd just hate to have to take apart the dash to see if it blocked though.

i do appreciate the input though! any other ideas?
 

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2008 chevy trailblazer_lt
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300 Posts
not sure if it applies, but do you get any flashing led indications? think the control is having problems reading / moving modes, as a result, it goes to "circulate outside", which then means it set the air flow to outside air along with "defrost position" for air flow to direct any / all air at windows to ensure that at the very least, your windows stay clear... even in summer...:). Just a guess though... flashing leds will support or tell otherwise.

Having said that, you DO need to know if your compressor is functioning for AC to be cold AND you also need to know if your water lines to your heater are appropriately hot to get heat.... these have to be checked, not guessed at.
 

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2005 chevy trailblazer_ls
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Discussion Starter #5
not sure if it applies, but do you get any flashing led indications? think the control is having problems reading / moving modes, as a result, it goes to "circulate outside", which then means it set the air flow to outside air along with "defrost position" for air flow to direct any / all air at windows to ensure that at the very least, your windows stay clear... even in summer...:). Just a guess though... flashing leds will support or tell otherwise.

Having said that, you DO need to know if your compressor is functioning for AC to be cold AND you also need to know if your water lines to your heater are appropriately hot to get heat.... these have to be checked, not guessed at.
No flashing leds (assuming you mean the ones on the a.c. and recirculation buttons. Recirculation will flash if I try yo put it on with the defog selected as the vent position, but otherwise no.)

Some one told me to check the condenser to see if it was getting cold at all, but it is not. I don't think the compressor is even kicking on, I don't hear a Chang in engine sound whether I have the a.c. on or not. That means it is either too low on Freon, the low pressure switch is bad, or some other electrical issue. I tested the clutch relay already, as stated, and I know that it is okay.
 

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2008 chevy trailblazer_lt
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300 Posts
well, you have "lots of problems". Basically, as suggested, you likely have a mode problem and thus the system is setting "out side circulation with defrost" for air flow. You have no / little heat because of that and the "mode problem"... likely stuck on AC. You have little / or no AC cause it ain't working for what ever reason that you need to find why.
 

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2005 chevy trailblazer_ls
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Discussion Starter #7
ok, so it is obvious that i need to take it in for service, as i have done all the basics that i can myself. but the question is now should i take it to the dealer, who may have more experience with it, but rip me a new one when it comes to price, or should i take it to my local guy, who doesn't specialize in chevy's, but is much more reasonable?

it is a 10 year old truck, and i have always found dealer service to be excessive, but for a problem like this, i worry that it might be my only way to get it resolved.
 

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2008 chevy trailblazer_lt
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300 Posts
your "poison" is yours for the choosing... :)

I work on all my "stuff" cause I can't afford the $100/ hr charges.

Anyways, personally, I would focus on the AC problem first. Get a meter and some form of gages to find out why it isn't coming on. That in its self will tell you what you are up against.

As for the "potential" mode issue, that is likely a heavy labor bill if it is an actuator as lots of stuff needs to be removed to get at it. The dealer is probably the best direction if you aren't able to do things yourself.

I suspect your AC problem is likely just a low charge... which unto itself isn't a problem as you can readily get a "walmart special" charge kit to top it up BUT... there is likely an underlying problem which may cause significant $$$ if left "unattended".
 

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2008 chevy trailblazer_lt
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You mentioned the old resistor was rusted. Moisture, dust, pollen and corrosion can build up in the system causing low air flow.
 
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