Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

AC problem

3K views 30 replies 14 participants last post by  jegnls1991 
#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?
 
#2 ·
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?
 
#4 · (Edited)
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
 
#6 ·
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.
 
#9 ·
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.
 
#13 ·
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.....
 
#18 ·
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.
 
#19 ·
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
 
#24 ·
check the overheat thermostat in compressor,.
Search the forum
requires a compressor change
I'm not educated to the possibility of an "overheat thermostat" on the back of these compressors.

I think they are LOW OIL sensors. I could be wrong, but an "overheat thermostat" isn't used much after (Hmmm - about) 1999 or so .... besides, they would be a 'thermal sensor', not a thermostat.

I think IF it was an overheat thermostat --- that would be a poor place to put it.

Still 'n all - I could be wrong.
 
#25 ·
I have the same 2006LS 4.2L and on a run from Florida to Tennessee on a warm, humid night, my condenser would freeze every few hours with 5 adults and a baby inside. I would turn off the AC, and wait a few minutes until the ice stopped flying out into my face (!) and turn back on for a couple more hours. Was only a few ounces low, but the combination of temp and humidity was enough.

At that point, the TB was 12 years old and the system had never been touched. Added about two ounces and had no more issues.

Last year, even though I have had no further issues, spent the money to evacuate and refill the factory amount - preventative maintenance.

All this to say: before shooting the parts cannon, begin with a simple evac/refill and go from there.
 
#29 ·
Assuming that your refrigerate levels/pressures are within acceptable range - good cooling for first 1 1/2 hrs is good evidence.
Next time it quits, pull over and look with a bright flashlight to determine if clutch is engaged.
Our 04 Envoy was doing something similar. Determined that the plugs for the 12v and grnd to the clutch on top of the compressor - had a little green crusties on the 12v - even though the rest of this Texas only vehicle had no other electrical corrosion.
Cleaned that up and got about 3-4 wks out of it, before the problem started again. Finally reluctant to mention it spouse started complaining about the intermittent operation, and shortly after the engine started a most alarming noise when cold.
Thinking the worst and thoroughly checking out the engine, I disc'd the serpentine belt and life was good again.

Net - AC clutch bearing. Upon removal from vehicle, clutch was very worn to say the least. As you will find, this style compressor requires a clutch that isn't designed serviceable, made by only 1 aftermarket source - which was $50 within cost of new ACDelco compressor. Having 135K miles on it at the time, took the opportunity to replace the comp, high pressure hose assembly, orifice tube, & accumulator. Then life was good again with reliable A/C.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top