Question about 2002 Chevrolet TrailBlazer

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No ac Hi my trailblazer isn't blowing cold air I think it might be a sensor because the temperature guage is reading 15 degrees and outside is really 95 degrees.

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  • tigd29 Aug 17, 2008

    Thank you for the great advice you're correct.



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The ambient air temperature sensor is bad or has a connection/wiring problem. It is not blowing cold air because it thinks the outside air is less then 35degrees. When the computer sees outside air less than 35 it disables AC so that ice will not form inside the vehicle and in HVAC system. The sensor is directly behind the front grill. You might be able to check it for connection/corrosion/frayed or damaged wires. If no evidence of this I would replace it.

Posted on Aug 16, 2008


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03 trailblazer is hard to start I have to turn the key 15-20 times before it starts. I put in new fuel pump, filter, relays good starter good just hard to start any suggestions on how to fix this issue. ...

You can check the fuel pressure regulator ,
  1. Inspect for a fuel leak from the fuel pressure regulator vacuum port.
Is the fuel pressure regulator leaking fuel ?
This next test needs a scan tool with data reading capability's ,not a code reader ! Are you familiar with OBD 2 ? All the sensors , coolant , O2S , TPS , MAF , Intake air temp. etc. Sensor/System
Monitor the engine coolant temperature (ECT) sensor with the scan tool. Compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, check for high resistance in the coolant sensor circuit.
Inspect the PCM grounds for being clean, tight, and in their proper location. Refer to Power and Grounding Component Views in Wiring Systems.

Inspect vacuum hoses for splits, kinks, and proper connections, as shown on Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction.

Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the mass air flow (MAF) sensor and the throttle body.

Inspect for air leaks at throttle body mounting area, mass air flow (MAF) sensor and intake manifold sealing surfaces.

Inspect the wiring harness for poor connections, pinches, cuts, or other damage.

Inspect for loose, damaged, or missing sensors and/or components.

Really need to check sensor PID'S with a scan tool, An maybe a scope too ! PID'S are parameter identification . All the sensors operate within a set voltage parameter , like the coolant temp. sensor an if it's off it can affect fuel delivery !

Mar 15, 2015 | 2003 Chevrolet TrailBlazer

2 Answers

AC recirculation is not working (outside temp is -37 degree centiigrade).

there is a damper that opens and closes to allow air to recirculate or come from outside. Find out where that is and check it out.

Dec 15, 2013 | 2011 Dodge Charger

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Outdoor thermometer reads -40 so the climate control system blows heat in the summer

sound like faulty out side air temperature sensor located center radiator support.

May 20, 2013 | 2001 Chrysler Town & Country

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Where is the blend door actuator located on 03 Hummer h2. Driver side blows cold, passenger side blows hot

They are not vac on the h2. there is 2 for temp control, one for recirc and one for blend. check the hummer forum as there is a great read for it there. the driver side actuator is really ez as it's under the glovebox, 20 min fix. the rest take removing the whole dash but it's not that tough.

Jan 10, 2012 | 2003 Hummer H2

1 Answer

I need to charge my ac system on my 1999 chevy s-10, what should the readings be on the ac manifold gauges?

With engine running, A/C on max and blower on full speed.
Allow 5 minutes running time like this for system to fully circulate.
Attatch guage to low pressure port.
At 80 degrees outside temperature, you should get between 45-50PSI reading on guage for a full charge. If you have a good reading like that and your A/C is not blowing around 36-40 degree air, most likely you have air in the system. Then a complete discharge of refrigerant in the system and full re-charge is indicated.

Jul 09, 2011 | 1999 Chevrolet S-10 Pickup

1 Answer

A/C blows but not cold air....the temperature reading is off...but then sometimes the temperature reading is fine and the air works

The outside air temperature is reading sometimes off then the ac does not work? The ambient air temperature sensor located right by the front grill is probably malfunctioning.If it reads below a certain temp it sees no reason to turn the air on so it doesn't let you.

Jul 17, 2010 | 2000 Pontiac Grand Prix

1 Answer

My inside temp led didplay always shows 50 degrees for my 2002 trailblazer so the Ac won't blow really cold air

If you mean the temperature display on the rearview mirror, you need to replace the outside temperature sensor. It is located under the hood, on the radiator support on the top near center.

Jun 15, 2010 | 2002 Chevrolet TrailBlazer

1 Answer

Air temp indicator only reads temps below 50 degrees

Ambient air temp sensor could be the cause. Normally located in front grille area.

Oct 06, 2017 | 2002 Chevrolet TrailBlazer

2 Answers

Misreading outside temperature sensor on 2001 Audi A4

There are four sensors for ambient tempurature and they work in unison to provide information to the temp reading on the dash, the heater control head ( where to direct air, blending of warm/cold/outside/inside air flapper controls) depending on the ambient temp and the inside air temp sensor located just above the radio as well as the sun sensor on the top of the dash as well as the a/c compressor head.

When you start your car, the body control module takes the readings from all sensors, outside air temp located in front of the radiator, air temp sensor located in the airbox ( senses temp of air being drawn in from the outside into the air box), coolant temp, inside air temp sensor and the sun sensor on top of the dash (this is why it takes a few seconds for the climate control system to begine when you start the car). The intake air sensor is 1st priority, inside air second, coolant third, ambient 4th and sun 5th. For instance, if the sun sensor reads the sun is hot but the interior sensor reads cold, the inside akes priority. The goal is for the system to achieve a tempurature inside the car that matches the selected temp. It uses all of the sensors to set the system up to achieve that goal as quickly as possible.

Example; Its mid afternoon, sunny and 40 degrees outside adn your in stop and go traffic. The intake sensor reads 40 degrees, the outside sensor reads 60 degrees (heat from radiator...engine heat protrudes into cabin) and the sun sensor reads high (sun is strong). The system is set for 72. priority one sensor reads 40, inside sensor reads 65, ambient reads 60= system will blow hot air to the floor out put, dash outlets will lightly flow 65 degree air so the sun doesnt roast you yet your feet are cold(if it blew hot air from all outlets, your upper body would be hot but your legs/feet would be cold). as the interior sensor reaches desired temp, air will be distrubuted through thee dash, defrost and floor with the warmest air coming out the floor and defrost, coolest air out the dash vents. Its a complex system!

The two sensors that will screw the system up the most are the intake and interior sensors. the system will function reasonably well with just those two sensors though it wont blend air temps between outlets if the sun sensor isnt working. If the outside sensor fails, it simply uses the intake sensor, if the intake sensor fails it will rely on the front sensor. However, since the intake takes priority over the outside sensor, if the intake sensor sends incorrect resistance info rather than failing, it will take priority and cause the unit to malfunction such as in your case.

The intake air sensor can be changed from the outside with patience. If it where me, I would pay the two hrs labor and let the dealer do it right.

Kevins Small Engine service,
South Berwick ME. 03908

May 01, 2009 | 2001 Audi A4

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