2003 Trailblazer A/C problem anyone?

2002 Trailblazer: I had this intermittent problem, blower working, but suddenly blowing hot air. Usually would do it upon starting. Stopping and restarting the engine would fix it. A dealer replaced the A/C low pressure cycling switch, problem still existed. They then replaced the ignition switch and I haven't had a problem since (since 2004)! Luckily this was all warrantly work.

There are a couple of TSB's on this that I would assume your dealer has
referenced, they also have access to a tech assisance line at Chevrolet.
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if the vehicle is equipped with abient temptature guge (ie it tells you how hot it is outside) and that is reading erratic replace that sensor ($35 maybe) Mine kept redaing crazy temps and the ac/heater auto temp couldnt decipher it so it would just blow hot (temp gauge was reading below 30 for outside even though it 90+)

Talk to the dealer, there is an updated part number for a special low
pressure switch...
89040362 Low pressure cycling switch..

Make sure they used that number for the part...

I also found this info... but it's probably the switch again.. somethings
wrong with a lot of the first design switches Bobo

HVAC System Inoperative for a Drive Cycle, Poor HVAC System Performance in
High Ambient Temperatures (Update HVAC Control Module Software)
#02-01-39-005 - (09/23/2002)
HVAC System Inoperative For A Drive Cycle, Poor HVAC System Performance In
High Ambient Temperatures (Update HVAC Control Module Software)

2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT

2002-2003 GMC Envoy, Envoy XL

2002-2003 Oldsmobile Bravada

Condition
Some customers may comment about no cold air from the heating, ventilation
and air conditioning (HVAC) system during a drive cycle. This concern may
occur at any time during the drive cycle and at any temperature setting. The
HVAC system operation returns to normal after the vehicle has been keyed to
off and restarted. This concern is intermittent and most likely to occur on
hot days. This concern may be found on vehicles equipped with manual (CJ2)
and automatic (CJ3) HVAC systems. Other customers may comment about poor
HVAC system performance in high ambient temperature conditions. This concern
may be present in automatic (CJ2) HVAC systems only. An HVAC control module
software update was put into all production vehicles beginning in September
2002. Vehicles built in September 2002 and earlier may need this software
update.

Correction
Update the HVAC control module using software available through GM Access
beginning September 9, 2002. The update will be fully available October 7,
2002 to all dealers on TIS 2000 CD version 10. This software update
addresses both the intermittent no cooling and the poor performance
concerns. If the software update does not correct the concerns, perform the
HVAC Diagnostic System Check and repair as necessary. If the HVAC control
module is replaced with a part from GMSPO, make sure the module has the
latest software update. The module may need to be updated even though it is
a new part.

...

my 2003 trailblazer air condition blows cold air on window & feet but will blow toward yoy any ideas

Yeah, I get the same thing in my 2003 LT 4x4. After about a month during a
hot spell here ( funky/humid smell. That went on for about 2 weeks, then it started working
fine again and has been OK for about a month. I want to take it in to get
checked out but have precious little free time and little hope of them
rooting out the problem if isn't acting up.

...

i had a problem with my ac not being cold and my ac compressor was making a high pitched squeel, i replaced that and i have had no problems it was about 800$ for the compleate system. if u change a ac compressor u must install the dryer system as well once u open the system u must change it all and it is complicated if you dont know much about them. belive me i changed mine my self and had a machanic help me with some work but all in all if ur ac isnt blowing cold air like it should and u have a squeel its the ac compressor straight up. i have 2 trailbazers in my family and both had a sam problem. i wont get a blazer again. toooo exspencive for stupid little problems. ill go for a avalanch LTz