Engine Cooling Issues (MY problem doesn't match any of the other forums issues/answers)

02TrlBlazer

Original poster
Member
Sep 6, 2018
1
Arizona
SORRY if I didn't post this to the correct forum/thread. . . . I am a newby at this

Briefly: My Vehicles,
2003 Trailblazer LTZ 2wd
-- -- -- 2002 Trailblazer LT 4wd (NEWEST Addition) -- -- -- THIS one has the issue
1999 Chevy K1500 4wd Ext. Cab
1999 GMC Yukon SLT 4wd

Cooling Issue: (Kinda long description, but want to give you EVERYTHING that has lead up to my conundrum)

Local Shops want:

$140 to Check PCM to see if settings that are sent to Fan Clutch are within parameters AND
$175 to download and update 02 Trailblazer PCM with latest HVAC Update for Fan Clutch from GM.

UMM. . . . NO, not at this point!

[1 of 3];

(1:smile: Issue: This vehicle DRIVEN "MOSTLY" with AC "ON"!

I just bought a 02 Trailblazer LT 4wd, drove it for a week and a half, temp gauge "normal" around 208 "TOPS" degrees w/ AC On (DRIVING or at IDLE - Temp) NEVER went over 208 degrees [Outside temps around 98-103 degrees ARIZONA) - (Dash gauge and Torque Pro scantool=same reading).

(2:smile: NOW:

Other than JUST buying this, I had to replace the alternator (Alt. off #1), battery, and the Quick disconnect (at the
heater core, SMALLER side if I remember correctly-left side of Heater Core standing in front) as it was leaking, so I replaced that, burped the system and,
everything as normal.

After around 2-3 days, i noticed that the temp gauge was heading "Stage Right" after driving for around 40 minutes(local roads), got up to 214-218 degrees. Shut AC off, and the temp started heading back down to almost CENTER mark.
Driving on freeway (AFTER driving for around 30-40 minutes) had SAME EFFECT, ran around 214-218 until AC shut off, then started cooling back down to around 210/208

In Short: (right after the 214-218 degree trip)
I replaced (just in case) Fuse #20 and RELAYS #39 & #40 (for future swapping if needed)

I changed Temp Sensor(Alt. off #2), Radiator Cap - SAME outcome.
I drove it for a week, NO Change

I THEN replaced the Thermostat (Alt. off #3 now), FLUSHED all of the Dexcool out and refilled with Prestone 50/50 and filled overflow tank with Prestone concentrate, burped system w/ heater turned on (blower fan OFF). Drove around - SAME outcome.

3 days LATER, I put large funnel in radiator, ran engine at around 2200 rpm WITH heater ON (blower OFF) for around 20 -25 minutes to create an ADDITIONAL "BURP" of system. . . a bunch of small bubbles came up, but nothing substantial.

2 days later, Drove to work & back. . . SAME outcome. Engine heated up to 214-218 degrees.

I added 2 - 9" electric fans to the A/C condenser and even that didn't seem to help cooling (driving OR at idle).

I then used my Combustion Leak Tester, after around 20-30 minutes with engine running, and came up Negative (all dark blue)


(3:smile: FINAL:
Driving in 100 degree heat;

Driving (street driving) NO A/C - engine heats up to around 208-210 (Torque Pro & Gauge)! PERFECT
Driving (street driving) A/C ON - engine heats up to 214-218 (AFTER around 30-45 minutes of driving);
Driving (street/highway driving MIX) with A/C ON - engine heats up to 214-218 (AFTER around 30-45 minutes of driving)
After stopped at an Idle with A/C ON or OFF = for 15-20 minutes - cools back down to 210/208

Clutch fan FEELS to be pulling a decent amount of air through the radiator, OBVIOUSLY it doesn't sound like a jet taking off, so it hasn't LOCKED up.

Do these Over-engineered clutch fans LOSE their grip AFTER a certain temp?

NO feathers/plastic bags/lose debris/cats or dogs blocking air flow to EITHER condenser OR radiator.


ANY SUGGESTIONS? I have browsed through a TON of these forums and people have "SIMILAR" issues, but none of them answers the issue that I have. Thanks in advance for ANY assistance or advice.
 

mrrsm

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Oct 22, 2015
7,641
Tampa Bay Area
If you can approach your car at the start of an average day and after dragging your finger along one of the fenders... you observe more dirt and debris than you might have thought was there... consider that even with the INTERNAL Flushing out of the Radiator and the Heater Core and renewing the Coolant-Anti-Freeze... your Thermodynamic problems might be caused by something EXTERNAL.

If you watch this Video from around 10:30 onward... this problem can be observed first hand where the detritus of Road Side Dirt and Grass Clippings can get inhaled over time and plug up a sufficiently large area of the Radiator Fins to prohibit the efficiency of getting proper Heat Transfer:


Gradually, this junk will get packed in between the fins and become a solid enough mass to prohibit the normal movement of ambient and fan driven air through all THREE Layers of Heat Exchangers: The Radiator... The Transmission Fluid Cooler and The Condenser Coil. Even something as innocuous as Small Plastic Shopping Bags and Large Maple Leaves can wind up getting packed in between these units and conspire to raise the Coolant Temperatures... in spite of how clean their 'innards" are and/or how Fresh the Coolant is. The vehicle involved in the Video is a 2000 Chevrolet Silverado 5.3L ... but the principle involved will apply equally to your 4.2L SUV:

CONDENSORDEBRIS.jpg

CONDENSORDEBRIS1.jpg

CONDENSORDEBRIS2.jpg
 
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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Sounds like the fan clutch may be dead and it's just spinning by freewheeling. Pull the relay and jump the connectors to see if the fan locks up. If it does, it's good. You could also use this method to test it.
How to test the electro-viscous fan clutch

Basically, if you can stop it without much effort, it's dead.

Yeah, those shops just looking at updating the PCM are quacks. There is an update but it was just for a clicking noise issue and shifting.
 
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