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Discussion Starter · #1 ·
When I use the AC for more than 1.5 - 2 hours it starts to blow warm air. It is ice cold before that. When I pull over there is a lot of water leaking from the evaporator drain. Any ideas?
 

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2004 chevy trailblazer_lt
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What year is your vehicle, which model & submodel (TrailBlazer EXT or Trailblazer), what engine and are there any OBDII codes, and what does the temperature indicator on the instrument panel read?

Do you have a set of A/C manifold gauges?
 

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Discussion Starter · #3 ·
2006 Chevy Trailblazer 4.2 4wd. No codes. Coolant temperature is 214f . I don’t have AC guages.
 

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2002 gmc envoy_slt
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You need to get gauges first. Take readings of high and low side. How many miles are on your vehicle? Where do you live? What are outside temperatures? The reason I ask is that I had an intermittent A.C. problem that only happened when it got really hot outside. Right when you need the AC the most....it would just shut off...During the cooler months it would run all day and freeze me out. Dealership couldn't figure it out...charged me $175.00 for nothing. Had it 10 days. I finally took it to an A.C. specialty shop....he took a wooden dowel and carefully pushed in on the clutch plate.....it engaged!!! It turned out to be a weak field coil in the compressor, when it overheated it would weaken.... and excessive "air gap" between the clutch plate and compressor hub. Some people have solved the problem by removing a shim from the compressor clutch assembly. I didn't know about the shim at the time so I replaced the complete compressor assembly. It solved the problem and many years later it is still working perfectly. HTH...c good
 

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Discussion Starter · #5 ·
The vehicle has 151000 miles. I live in Las Vegas. Outside temperature is over 110F. AC clutch engages.
 

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You'll need to get and report the low side and high side pressures when the AC system is operating normally and freezing you out. Then you'll also need to get and report the low and high side pressure when the AC system stops blowing cold air and is blowing warm air. Also, while leaving the AC system on when it starts to blow warm, look at the AC compressor and verify that the clutch is indeed engaging.

One very important question before I forget - is your HVAC system a manual system or an automatic system? Manual is where you select the temperature along a scale from cold to hot, and an Automatic system is one where you set a numeric temperature.
 

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2002 chevy trailblazer_lt
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The vehicle has 151000 miles. I live in Las Vegas. Outside temperature is over 110F. AC clutch engages.

So just to confirm.... When it has stopped working, you have opened the hood and visually seen the front portion of the AC Clutch spinning while you have no A/C,,, correct??
 

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Discussion Starter · #8 ·
So just to confirm.... When it has stopped working, you have opened the hood and visually seen the front portion of the AC Clutch spinning while you have no A/C,,, correct??
It doesn't stop working. It just blows warm air after an hour or so on long trips. It does get cold air at first. Yes I have done visual inspection and the AC clutch is spinning.
 

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Hey guys ---- this is the old ice-up syndrome in the evaporator.

It's icing up and blocks the air flow and stops chilling the air.

The abundant melted condensate under the AC plenum is the big clue.

This is either a bad thermostat or a slightly low Freon charge.
 

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Discussion Starter · #10 ·
Hey guys ---- this is the old ice-up syndrome in the evaporator.

It's icing up and blocks the air flow and stops chilling the air.

The abundant melted condensate under the AC plenum is the big clue.

This is either a bad thermostat or a slightly low Freon charge.
Bad thermostat?
 

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Bad thermostat?
Yeah --- there's a thermostat --- or sensor that is in the evaporator to measure the temp of the core to keep it from freezing.

When the temps get too low, it might cycle the compressor - or some older systems had an EPR or POA valve to handle the problem.

Most likely it's a solid-state device that has no moving parts and requires a C-note to get it ordered from GM and another C-note when it arrives.

Oh --- I see !!! You thought it might be the engine coolant thermostat - right? <wrong>
 

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Discussion Starter · #12 ·
Yes. You are right. Is that separate part from the evaporator. Or I have to replace the evaporator?
 

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I haven't been inside one of these yet - I retired in 2004 and I never saw the vehicles we are driving.

But wait right here and someone will know.....
 

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No.

This is going to be involved with the core temperature of the evaporator (under the dash) 'cause I don't think there's a superheat sensor on the back of the AC compressor - just a Low Oil sensor.
 

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When are you going to realise a Trailblazer is a lemon POS and you need to just quit spending money on it and ride it until it dies. Dont sell it to some poor sucker like me. Ride it til its dies and quit spending your time money and grief on these god awful suvs
 
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