Chevy Trailblazer A/C takes FOREVER to cool down

[Nick1994]

I've been driving my grandparent's 2002 Chevy Trailblazer LTZ (110k miles) daily, and with this heat the A/C just can't keep up. When starting it up and driving it takes about 10 miles at least for the A/C to start to cool off. I usually go start the car and let it run for 10 minutes before we leave anywhere, and that helps a bit to start it to cool.

A mechanic friend of mine has looked at it the past couple years and added a small amount of refrigerant a couple times, and the pressures have been fine so no major leaks. he hasn't looked at it this year but I figured I would ask on here first. When it isn't so hot out, such as Spring time, it does fine and blows ice cold. After a long trip in the car, 20+ miles, it blows very cold. But it just takes FOREVER to cool off. Once it does, it's fine.

Is there a typical thing that goes wrong for this symptom?

 

[DemoFly]

Clean the condenser coil. Make sure the fan clutch is working the way it's supposed to.

Get a check and charge at a shop.

 

[skyactiv]

This year is different than last year, so it needs looked at again.

 

[Nick1994]

Originally Posted By: skyactiv
This year is different than last year, so it needs looked at again.
Yup, it's just done the same thing every year. Was wanting to check on here to see if there's specific things that's common to make it do this.

 

[The_Eric]

Give the evaporator a bath.

 

[mclasser]

Pay attention to the compressor cycling. In AZ heat, it should stay running for the most part at higher blower speeds.

 

[Kuato]

In addition to the above:

Park in the shade.

With AC on norm, crack open all the windows to allow hot air to escape; it will cool down much faster than with the windows closed and Max/AC.

Move north.

 

[Nick1994]

Originally Posted By: Kuato
In addition to the above:

Park in the shade.

With AC on norm, crack open all the windows to allow hot air to escape; it will cool down much faster than with the windows closed and Max/AC.

Move north.

Lol if only it were that simple.

All 4 windows are always cracked, and then rolled all the way down for about 1 block down the street.

I know there's a problem, because my car has ice cold A/C after a mile or so, and starts to get cool right away. And any of the other cars I've had or driven do too.

 

[Kuato]

Originally Posted By: Nick1994
Lol if only it were that simple.

All 4 windows are always cracked, and then rolled all the way down for about 1 block down the street.

I know there's a problem, because my car has ice cold A/C after a mile or so, and starts to get cool right away. And any of the other cars I've had or driven do too.



Check!

 

[mikered30]

Check this out: https://www.youtube.com/watch?v=r_em9lm69HQ

 

[Chris142]

Start by doing it correctly. Suck the refrigerant out. Vacuum and refill by weight.only then you can diagnose other problems

 

[jyoung8607]

There's a TSB that covers some model years, I don't recall which ones but I know it covered my wife's old '04 TrailBlazer. Google should find it. The short version: not enough airflow over the condenser when stopped or at low speed, due to the old fan clutch design and wear and PCM programming. Fix was a revised fan clutch with a higher minimum speed, plus a PCM flash update to command a little more fan engagement at startup.

We had both done, the revised fan clutch and the PCM flash update (indirectly via a PCM4Less tune). In my experience, and anecdotal feedback seen from others on the interwebs, the revised fan clutch alone gets you most of the benefit.

Jason

 

[Nick1994]

Originally Posted By: jyoung8607
There's a TSB that covers some model years, I don't recall which ones but I know it covered my wife's old '04 TrailBlazer. Google should find it. The short version: not enough airflow over the condenser when stopped or at low speed, due to the old fan clutch design and wear and PCM programming. Fix was a revised fan clutch with a higher minimum speed, plus a PCM flash update to command a little more fan engagement at startup.

We had both done, the revised fan clutch and the PCM flash update (indirectly via a PCM4Less tune). In my experience, and anecdotal feedback seen from others on the interwebs, the revised fan clutch alone gets you most of the benefit.

Jason
I've thought about the fan clutch, but it seems to be working. I've also sat in a parking lot and held the gas pedal at 2,500-3,000 RPMs for quite a while and it doesn't make a difference. That's more air flow and a faster spinning compressor.

Even when I first fire it up and get out on the highway (1/2 mile away) it still takes forever to cool down.

 

[Falcon_LS]

Experiences running a GMT360 in 130+ F heat.

These trucks do not like hot climates. If it's parked under the sun, it will take forever before the AC starts to cool down. The interior space is pretty big, with most of the cool air coming from the vents on the dashboard. The vents on the center console are not effective.

When you turn on the AC, hit the recirculate button and make sure the AC switch is on so both LEDs are illuminated. Although the engine spins the fan, the fan clutch is controlled by a PWM signal. At 600 rpm with the AC off, the fan spins at ~750 rpm, moving about 2,050 CFM of air. When the AC compressor runs, the PCM commands a 10% higher fan RPM because there is no separate condenser fan. When you're driving 60 MPH on a flat road, the commanded RPM is in the 800 range, so the fan isn't going to help much. If you simply hit the recirculate button, but not the AC button, the AC compressor still kicks in but without the +10% fan RPM.

Here's what I suggest you do. Replace the orifice tube with GM P/N 19189843, which is for hot climates. I would also replace the freon - Mexichem Fluor KLEA 134a, if you can get it, is worth the money. It is extremely popular in this part of the world with a renowned reputation for better cooling. I don't know about its technicalities, but I do know it did make a difference in my applications.

Before adding any freon, preferably after the truck's been sitting overnight, remove the front radiator grille and using a garden hose, rinse it thoroughly. Grab some Simple Green Automotive Degreaser and liberally spray the condenser and let it sit before rinsing it again, with a little pressure. Fire up the engine, hook up your equipment and keep hosing down the condenser for the first minute as you add freon with the compressor running. If ambient temperature is over 110 F, low pressure will hit 60 PSI before the system is full.

Just came back from a 30 minute drive with the AC running and an ambient of 118 F and the AC has been cold, the receiver drier is ice cold.

 

[Falcon_LS]

Originally Posted By: jyoung8607
There's a TSB that covers some model years, I don't recall which ones but I know it covered my wife's old '04 TrailBlazer. Google should find it. The short version: not enough airflow over the condenser when stopped or at low speed, due to the old fan clutch design and wear and PCM programming. Fix was a revised fan clutch with a higher minimum speed, plus a PCM flash update to command a little more fan engagement at startup.

We had both done, the revised fan clutch and the PCM flash update (indirectly via a PCM4Less tune). In my experience, and anecdotal feedback seen from others on the interwebs, the revised fan clutch alone gets you most of the benefit.

Jason


The updated fan clutch applies to vehicles built before 06/2005. Mine was built in 02/2005, so I replaced mine with an ACDelco 15-40133. I would not recommend aftermarket fan clutches for this application, you won't end up "saving" anything.

 

[Falcon_LS]

Forgot to mention, the OE fan is made by Behr Hella Service GmbH.

 

[Nick1994]

Forgot to update. Trailblazer is fixed, it was mostly the fan clutch. Fan never engaged, when revving the engine it didn't do anything as far as speeding up the fan. The fan stayed the same speed. New fan clutch from dealer and it is totally different, fan roars at startup and roars when your rev it. I had my mechanic friend replace it and he replaced one of the pressure valves for the A/C. It was leaking and he recharged it. New radiator hoses as well as a new ambient temperature sensor as a just in case and it is golden.

A/C is ice cold, I honestly couldn't ask for it to be any colder. It's very important to me that my grandparent's cars are in tip top shape, because their health isn't so good and being broken down in the middle of nowhere is the last thing they need.

I drive their car 80-90% of the time so I'm glad the A/C is cold

Took it into the dealer today for the software update and they said there is no software update for it. They did an alignment too, I'll go pick it up soon and see how it is.

Thanks for the help everyone!