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2003 chevy trailblazer_lt_ext
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21 Posts
Discussion Starter #1
I live in Arizona where it can get warm and hot.

Recently I noticed that the A/C is not getting cold and barely cool. The A/C seems to be cooler in the morning when the temperature is not as warm. But once it warms up, the A/C is really no relief.

I noticed when I was in the vehicle that the A/C was not working properly and then the "Ambient Air Temperature Sensor reading" in the mirror was way off. It claimed that it was 140 degrees. It went down to 99 degrees afterwards.

I thought I had came across the thread that mentioned a fix for this but I can not find it now.

I would love to get my A/C blowing cold air like my 97 Z71 does (knock on wood that my Z71 A/C keeps on working like it does).

The fan settings for the front and rear work. The light indicating A/C is on. I tried to reset the actuator by:
1-Place the ignition switch to the off position
2-Remove the HVAC B fuse (fuse #36)
3-Install the HVAC fuse
4-Start the vehicle
5-Wait 40 seconds for the HVAC control module to self-calibrate

At least that is what I found on this site.

Any ideas or help? Thank you.
 

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2009 chevy
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6,431 Posts
I doubt if the HVAC requires recalibration, the temp sensor may need to be replaced (under $20, mounted on radiator support).

I suspect the refrigerant charge is low, probably because of a leak.

Buy a recharge can from Wal-mart (the one with the pressure gauge).
You can check the pressure and add some refrigerant if need be.
 

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2005 chevy trailblazer_ls
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1,401 Posts
Mine runs well in the morning just like you stated, and then come afternoon its not got much cool air coming out of it at all. I noticed my dad's 09 silverado is extremely cold compared to mine, not to mention in my mom's toyota highlander that AC will freeze you out of that car! I had tried putting more refrigerant in; in the past.. took it to the dealership and they said I put too much in it or something like that... I dont remember exactly but I tried putting just a little bit in the other day, it seemed like it might have helped ever so slightly.. But honestly this is driving me nuts. Mornings it's fine here but come afternoon its about 100, even after letting the AC run for a while having the top of the window opened some to let the hot air out... its still hot as can be.
 

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2003 chevy trailblazer_lt_ext
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Discussion Starter #4
I suspect the refrigerant charge is low, probably because of a leak.

Buy a recharge can from Wal-mart (the one with the pressure gauge).
You can check the pressure and add some refrigerant if need be.
I did buy a recharge can and tried but the gauge on my recharge kit showed that the pressure in the system was in the "warning" area. I am guessing too much pressure..
 

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2009 chevy
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6,431 Posts
I don't know how it could read high, unless someone over charged it.
Perhaps the pressure should be checked by a pro.

To cool, the compressor needs to run, this is activated by the compressor clutch.
You should be able to hear a click, and feel a small change in the engine rpms, as the clutch operates. Test this with the door open and the engine running.

If the clutch does not click, the low pressure switch may be preventing the operation.
The switch tells the PCM it is ok to operate the compressor.
When A/C is required, the PCM commands the clutch relay (#44) to operate.
This relay may be bad.
 

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2005 chevy trailblazer_ls
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1,401 Posts
I don't know how it could read high, unless someone over charged it.
Perhaps the pressure should be checked by a pro.

To cool, the compressor needs to run, this is activated by the compressor clutch.
You should be able to hear a click, and feel a small change in the engine rpms, as the clutch operates. Test this with the door open and the engine running.

If the clutch does not click, the low pressure switch may be preventing the operation.
The switch tells the PCM it is ok to operate the compressor.
When A/C is required, the PCM commands the clutch relay (#44) to operate.
This relay may be bad.
So we have AC on.. and try these steps correct? I believe that is what is done with home AC units to check the freon level... wonder if my dad's friend's refrigerant guage thats electronic that works on stand alone A/C units would be able to read anything off the tb.
 

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2002 gmc envoy_slt
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91 Posts
The reading on the gauge reads high because the clutch is not engaged. Therefore the a/c is not circulating, even though it's on. When it cools down and you actually feel cool air coming out the vents, you know the clutch is engaged, that's when you connect the can and the gauge. It should be in the blue area, if it's in the yellow, it might be overcharged, if green undercharged. :m2:
 

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2003 chevy trailblazer_lt_ext
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Discussion Starter #8
Well, I went to a shop to see if they could troubleshoot it and I was informed that everything is working fine. Note: the temperature at the time was below 90 so of course the A/C works fine. It is only during the warm time/days that it fails.

I was informed though that there is a Technical Service Bulletin on the issue, #04-01-38-019A. "Intermittent Slow to Cool HVAC Performance Concerns in High Ambient Temperature and/or High Humidity Conditions.

What it states for the correction is to install a new engine cooling fan clutch.

Is there a step by step, maybe with pictures, on how to do this? The dealer and shop wants $$$ ($345 from shop and $400+ at the dealer) for the fan clutch but I found it at http://www.am-autoparts.com/2003/Chevy/Trailblazer-EXT/RadiatorFanClutch/AM-18868449/326210.html for $107.

Any suggestions. I did disconnect and reconnected the Ambient Air Temperature Sensor due to the goofy reading I had earlier in the day and ever since then, the A/C and the Ambient Air Temperature Sensor
reading appears to be acting normal. Coincidence?
 

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2004 gmc envoy_slt_xuv
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691 Posts
Well, I went to a shop to see if they could troubleshoot it and I was informed that everything is working fine. Note: the temperature at the time was below 90 so of course the A/C works fine. It is only during the warm time/days that it fails.

I was informed though that there is a Technical Service Bulletin on the issue, #04-01-38-019A. "Intermittent Slow to Cool HVAC Performance Concerns in High Ambient Temperature and/or High Humidity Conditions.

What it states for the correction is to install a new engine cooling fan clutch.

Is there a step by step, maybe with pictures, on how to do this? The dealer and shop wants $$$ ($345 from shop and $400+ at the dealer) for the fan clutch but I found it at http://www.am-autoparts.com/2003/Chevy/Trailblazer-EXT/RadiatorFanClutch/AM-18868449/326210.html for $107.

Any suggestions. I did disconnect and reconnected the Ambient Air Temperature Sensor due to the goofy reading I had earlier in the day and ever since then, the A/C and the Ambient Air Temperature Sensor
reading appears to be acting normal. Coincidence?
The Auto HVAC systems use the ambient sensor and other sensors to adjust the auto operation. I have heard where owners that had the ambient temp read way too low that the A/C did not blow as cold as it needed. (auto unit thought is was actually cold outside and compensated)
 

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2003 gmc envoy_slt
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331 Posts
The TSB mentioned is a fix for low speed/idle poor ac operation. If your situation is poor ac performance at higher speeds then it's not a fix. I've had it done but I could actually count the fan blades at idle it was turning so slowly. The fan did not move enough air thru the condenser at idle and the system would shut off because of high pressure. If your problem is at low speed then a new fan clutch may solve your problem
Second issue is the temperature reading isn't instantaneous. I don't recall the algorithm but the update is a function of speed and how long the vehicle has been at rest. The idea is not to give a false reading from air recirculated thru the radiator. From what you reported of 140° I doubt this is your problem. Even 99° seems a little high for Holbrook. It's my recollection the reading should be close to ambient after the vehicle has set a couple hours. Any thing less and it updates as a function of speed. At a minimum you might unplug the thermistor and look at the contacts for corrosion and plug back together
 

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2002 gmc envoy_slt
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539 Posts
You need to confirm if the compressor is engaged and spinning when the performance drops off. If the compressor stops running, you either have a bad Low Pressure cut out switch or a bad clutch coil in the compressor. I had a similar problem. A.C. would run all day at temps under 84 degrees. Over 84 it would run for a while and then suddenly get warm. I confirmed the compressor was cutting out by visually inspecting it when air warmed up. It eventually turned out to be a bad compressor clutch coil assembly. New compressor time! VERY COMMON on this vintage of compressor. HTH. Check this out and let us know what you find so we can continue to help. c good
 

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2007 chevy trailblazer_lt
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83 Posts
This may seem really obvious but the AC in an 02 work pickup I had was running decent and then deteriorated over time. It got to the point where it wasn't blowing cold air at all. Decided to check the front of the radiator. It was absolutely caked with bugs and dust. I hosed it off. The mat of dirt and bugs peeled off in sheets. Once it was clear, the AC ran like new again. Amazing what airflow can do!
 

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2003 chevy trailblazer_lt_ext
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21 Posts
Discussion Starter #13
I have a question about the electronic cooling fan clutch. My friend has had his replaced his 2-3 times by the dealer and still when the weather is high temperature or high humidity you hear that loud noise, like a sound of high revving sound.

Is this a design flaw on the Trailblazer or cheap parts? I hate to replace mine it if the new one will do the same that my friend's does after a short time.
 

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2004 gmc envoy_slt_xuv
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691 Posts
I have a question about the electronic cooling fan clutch. My friend has had his replaced his 2-3 times by the dealer and still when the weather is high temperature or high humidity you hear that loud noise, like a sound of high revving sound.

Is this a design flaw on the Trailblazer or cheap parts? I hate to replace mine it if the new one will do the same that my friend's does after a short time.
There are times that the fan will normally make that noise because it is trying to move a lot of air for cooling needs. Don't take the noise as a failure, If it makes that noise 100% of the time, even when cool outside, it is a problem.
 
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