2003 trailblazer, ac not working (compressor not coming on nor the belts turning). The outside temp gauge says it is 3 degrees F when it is actually 90+. Is this a sensor switch problem?

A system will only drop temp about 20 degrees from outside temp. I would have then recheck the Freon level again. To much is as bad as to little when it come to Freon. Also the oil level can be to high causing the same thing. When they changed the compressor they should have also replaced the dryer and the orfice tube/screen. If that wasn't don't you could have a obstruction in line.

You need a repair shop with a/c knowledge to work on it

When you try & add to a leaking system & I fail to see
why people do,you let air in & over charge it

If the cooling system is functional, yes.
The ac condenser adds heat to the air coming thru the radiator when the ac is on. If the engine cooling system is weak, the extra heat will make the engine run hot.
Low coolant flow thru the radiator is a common cause.

check compressor clutch clicking in when you turn on and off or belt tight enough

Does the engine over heat or the gauge goes to hot. Really hot. Since the A/C is on , this puts an extra load on the engine. This is why the fans come on when the A/C is turned on. This is usually low speed fan mode. High speed doesn't come on untilll 220 to 230 degrees. Most vehicles. Cars don't over heat untill the gauge gets in the red, when it starts getting close is time to worry and stop. I guess the question to you would be, What does the temp gauge read?

Ok..that is a strange one.. I am going to hazard a guess and suggest you look to the AC compressor.

When you run the defroster the ac compressor comes on..typically whenever the outside temp is above 40 degrees.. the ac compressor kicks in to dry out air inside.

Often when it rains.. the windows fog.. you turn on the defrost.. the ac compressor tries to come on.. and.. there ya go.. rather there your serpentine belt goes.

Several things could cause this.. worn belt.. failing belt tension-er... or failing ac compressor..

If the ac compressor is frozen meaing it will not turn..when the electric clutch on the front engages.. it would cause the pulley to stop turning.. and the belt would have a hard time staying on a non rotating part.

Or if the belt tension-er is bad..or the belt is worn.. when the additional load of the compressor kicks in.. it jumps off.

Finally it could be a combination of all three..


Best of luck..

You need to replace the temperature sensor, it is located under the hood, in front of the radiator, on the upper support rail.

If the outside temp.sensor is reading -38 degrees then this is what is causing the compressor not to come on.You need to check the wiring to the outside temp.sensor and the sensor.Make sure it is connected.It is located on the front grill area.Between the grill and the bumper cover.Hope this helps.Good luck.

Your Trail Blazer does not have a rear compressor. It will have a rear expansion valve and a rear evaporator core. Changing the line will depend on exactly where it is leaking. The lines run all the way from the front to the rear so it can be a chore. Do you know which line it is and about where it is leaking? There are a high and low side line, and they will have connections in places. With more info on the location I can look it up on the GM service site and give you more info. Good Luck

the sensor is in behind the nosecone. but this should not effect the ac system . it would it the inside temp sender said that in the auto mode only. put it in defrost mode and the compressor should be on if not you have another problem (maybe low on freon)