Hot A/C at idle, Engine temp little high

954gooner

Member
Hello,

For the past few days I have noticed that when I'm stopped at a light, my AC blows hot. Not cool, nor warm, but HOT. Once the truck is moving again, back to blowing refreshing ice cold air. Then today I noticed, as I was parking of course, my temp a few ticks past the 210 mark. I replaced the Thermostat and sensor about 8 months ago, and replaced all the coolant at the same time. In searching the forum, I'm leaning towards it being the fan clutch, but wanted to see if anyone had some other suggestions or quick check before replacing it.
 

CaptainXL

Well-Known Member
Do you have a CEL or codes? If the fan clutch wasnt working right at idle I would think the PCM would sense an underspeed of the fan and throw a code.

Could possibly be low refrigerant, an overheating compressor or bad ac clutch. There are people on here that should have a more concrete answer. Would wait to see what they have to say.
 

triz

Well-Known Member
I'm going with your AC Clutch. Mine did the same thing till it locked up and snapped my belt.
 

meerschm

Well-Known Member
scan tool is a good idea.

should be able to make this happen, just drive it and stop in your driveway, (or a parking lot)

see if the coolant temp is increasing. and what temp it is getting too. As may03LT pointed out on another thread, if it is too hot, the computer will turn off the ac. not sure how hot this has to be.

with the engine warm, your fan clutch should fully engage. when the fan clutch is not engaged, you can stop it while the engine is spinning( use a rag and/or some heavy gloves and slowly grab the edge, keeping fingers well away from the fan blades. you can try this when it is very cool.. when it is hot, you should not be able to do this. you also should be able to tell the difference in air flow.

when the fan clutch gets flaky, it just does not engage when it is too hot. mine did this, at first when fully loaded with vacation crap and stopped in traffic before a toll booth in 100 plus temps (last summer) got worse over time, and would do it in high 80s this spring.
 

CaptainXL

Well-Known Member
There is no need to do any of this. According to the service bulletin there should be a DTC set if the fan clutch is not working right. The speed of the fan clutch varies and isn't necessarily locked up full.


Cooling System - Electro-Viscous Fan Clutch Operation



Bulletin No.: 06-06-02-003

Date: February 14, 2006

INFORMATION
Subject:
Operating Characteristics of the Electro-Viscous (EV) Fan Clutch and Diagnostic Tips for Cooling Fan Noise, Delayed Transmission Shifts and/or Engine Revving Too High
Models:
2004-2006 Buick Rainier
2002-2006 Chevrolet TrailBlazer, TrailBlazer EXT
2006 Chevrolet TrailBlazer SS
2002-2006 GMC Envoy, Envoy XL
2004-2005 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
2005-2006 Saab 9-7X

with 4.2L I-6, 5.3L V-8 or 6.0L V-8 Engine (VINs S, P, M, H - RPOs LL8, LM4, LH6, LS2)

Date/VIN Breakpoints for Vehicles with New EV Fan Clutch


View attachment 29028




Vehicles built after and including the Date or VIN Breakpoints listed in the table shown are equipped with the new electro-viscous (EV) fan clutch.

Vehicles of any model year listed in "Models Affected" with labor code J3390 (claimed after June 8, 2005) with P/N 15293048 in Claim History may also be equipped with this new EV fan clutch.

After having service for poor HVAC performance and/or engine cooling performance, some vehicles may exhibit fan noise, delayed transmission shifts, or the engine revving too high.

These conditions may be caused by expected operating characteristics of the new design electro-viscous (EV) fan clutch. This new design EV fan clutch has been installed on production vehicles from the end of 2005 model year production (June 2005) and all 2006 model year vehicles. The new design EV fan clutch may also be present on vehicles serviced with this new part per Corporate Bulletin Number 04-01-38-019A or for other service related conditions.

The updated design of the electro-viscous (EV) fan clutch helps improve A/C performance but may also produce some additional fan engagement noise.
Important: Unless a specific issue is identified by proper SI diagnosis, do NOT replace a fan clutch for fan noise.

Do NOT replace an EV fan unless a specific condition related to the EV fan is identified using SI diagnostics. If the fan has a condition that warrants replacement, a DTC should set and/or SI diagnostics should lead to the replacement of the fan clutch.

If the fan is not operating at the proper speed/function, the appropriate diagnostic trouble code should set.

Identify the root cause of the condition. Please make sure to do a thorough review of SI for proper diagnostics. Several Service Bulletins and Preliminary Information are available on SI regarding the EV fan.

Refer to "Operating Characteristics" and "Diagnostic Tips" in this bulletin for additional information.

Operating Characteristics of the Electro-Viscous (EV) Fan Clutch

Changes to the EV fan clutch to improve the HVAC performance basically increase airflow in certain conditions. It is now possible during start up for the EV fan clutch to be engaged and match engine speed for about 1 minute depending on driving speeds (with lower speeds having a longer disengagement time) producing some noise/flare. The noise/flare will most likely be intermittent and can be dependent on the following conditions:

^ Fan clutch valve orientation, with check ball at 11:00 position as viewed from front of vehicle when the engine is stopped.

^ HVAC or powertrain cooling conditions when the vehicle is shut off.

^ Parking incline - vehicles parked nose up on a 16% or higher incline (such as vehicles coming off transport or parked on steep driveways) may have prolonged fan noise/flare until the fluid is pumped out of the working chamber of the fan. These conditions can occur in as little as ten minutes. Once the vehicle is not parked in these conditions, it should operate as expected.

^ Please note that if the vehicle is parked nose down with a 16% or more decline, the EV fan clutch may have a delayed engagement response similar to what is described in Corporate Bulletin Number 04-01-38-019A.

Important: Do not replace EV fan clutches for these conditions listed above; they are expected vehicle characteristics. If the fan clutch is truly operating at a speed higher than intended, a DTC P0495 or P1484 should set. Additional codes are available for other conditions.

Diagnostic Tips

Depending on the vehicle year, the Tech 2(R) may allow some EV fan control using the special functions application of the Tech 2 (refer to the proper SI documentation). If this function or a fused jumper wire is being used to check EV fan response, there may be a delay in fan response (up to 2-3 minutes depending on conditions, please refer to SI diagnostics).

The desired fan speed and actual fan speed data (on the Tech 2(R)) can be misleading. The desired fan speed is comprised of the maximum of multiple parameters (for example engine coolant temp, A/C pressure, etc.) and may not be the ruling desired fan speed parameter. The end result may be that the actual desired fan speed is lower than what is displayed.

Additionally, the desired fan speed may be higher than the current engine speed. The fan is limited by the current engine RPM and will max out at about 3500 RPM under full manual fan engagement request along with a corresponding engine RPM speed. The 4.2L 1-6 (LL8) engine's desired and actual fan speeds will usually be closer to each other than the 5.3L V-8 (LM4 or LH6) or the 6.0L V-8 (LS2).
 

Attachments

meerschm

Well-Known Member
good point. flakey fan clutch should throw the codes.

just look under the hood and see if the fan is blowing like heck, and the ac clutch is not engaging when it is hot.

the compressor clutch can start to quit when it is hot, then start to work when you move more, and it cools off a bit.

in these conditions, it is possible the temp skootches up when you stop and it is hot anyway, but you just do not notice until the ac quits and you look around.

I actually changed my fan clutch because i thought it was the problem, which was fun, but did not fix the problem.

a few weeks ago I installed a rebuilt AC clutch, and will see how it works when it gets in the mid 90s next week, so far so good.
 

CaptainXL

Well-Known Member
Not sure exactly what's wrong with mine. The AC works at times and not others. Seems worse stopped at intersections with hot and humid temps 80F+.

Something is telling me it's not the clutch because the high pressure is fine. In my mind this would be a conclusive enough test...to check the high pressure side. This will tell you if the compressor and clutch is working.

I would be more concerned about the compressor overheating and tripping off.
 

meerschm

Well-Known Member
when the clutch gets flaky, it just does not engage the compressor.

it takes more force to start to move than to stay engaged. and when engaged, the clutch plate is closer to the coil.

this is not related to the high pressure reading.
(except that if the clutch does not engage, the pressure will not get high)

my pressures were fine, but when the compressor clutch got hot, it did not engage. could be it got weak, or could be the coil developed an open at temp.

it also may be that the gap has increased. mine did not, but some folks have indicated a reduced gap solved their problems. (remove the clutch plate by taking off the shaft nut, and reduce the number of washer shims.) if you have a set of feeler gauges, you can check the gap. mine did not increase and was just over .020 when I changed it out.
 
OP
OP
9

954gooner

Member
Letting the truck get to operating temp on a 93 degree day, put a rag on my hand and was easily able to stop the fan. Took a good second for the fan to get up to speed. this would be the fan clutch, correct? However, I'm still not getting a thrown code. any thoughts gents?
 

gmcman

Well-Known Member
You can disconnect the ECT sensor which the harness is located near the FPR and this should fully engage the fan. If it doesn't then I would suspect the fan clutch. Usually they just begin to engage more and more but something to try.
 

meerschm

Well-Known Member
not sure just the coolant in the engine up to temp would force the fan clutch to fully engage. (engine at 210 f open thermostat, but radiator still around 100f. no huge issue.

if it easily could be stopped when it was really warm, (like when your ac stops and blows hot) it would be more likely.

then it could be the culprit.

can you make the ac blow hot? (when it is supposed to be cold?)


and another reminder, I convinced myself it was the fan clutch which I changed, and ended up changing the compressor clutch, since the new fan clutch did not fix the ac issue i had.
 
OP
OP
9

954gooner

Member
meerschm said:
not sure just the coolant in the engine up to temp would force the fan clutch to fully engage. (engine at 210 f open thermostat, but radiator still around 100f. no huge issue.

if it easily could be stopped when it was really warm, (like when your ac stops and blows hot) it would be more likely.

then it could be the culprit.

can you make the ac blow hot? (when it is supposed to be cold?)


and another reminder, I convinced myself it was the fan clutch which I changed, and ended up changing the compressor clutch, since the new fan clutch did not fix the ac issue i had.
I'll try to replicate the situation tomorrow and see what the fan does. If not the fan clutch, can the ac clutch be changed independently of the compressor?
 

Mooseman

Moderator
You are posting to a long dead thread with most of those that posted to it that haven't logged in for years.

That being said, the OP's issue was likely the fan clutch. Test it using the methods here:
How to test the electro-viscous fan clutch
 

Mooseman

Moderator
What brand clutch? The cheap no-names and Dorman are iffy at best. Does it lock up and sound like a dump truck if you jump the relay terminals? And doing that, does A/C performance improve?

After that, check the charge in the A/C system with a full set of gauges. An improper charge can cause issues.
 

Stone

Member
What brand clutch? The cheap no-names and Dorman are iffy at best. Does it lock up and sound like a dump truck if you jump the relay terminals? And doing that, does A/C performance improve?

After that, check the charge in the A/C system with a full set of gauges. An improper charge can cause issues.
Ac delco

Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

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Fan clutch not engaging

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Stone615
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Discussion Starter • #1 20 h ago (Edited)
04 xuv slt 260k+ i6 engine

Recently replaced:
Fan clutch
Water pump
Thermostat
Relay

Symptoms:
intermittent over cooling
Overheating in traffic/idle
Ac not blowing cold unless driving. Randomly hear a pssst sound as if it has an air break blow off. Can feel the truck drag momentarily when this happens.
Fan does engage from time to time, but not like it should


The fan does kick on from time to time. Im at a loss for what to do next. I thought about the temp. Sending unit but the gauge works fine.
 

Mooseman

Moderator
After that, check the charge in the A/C system with a full set of gauges. An improper charge can cause issues.
Try to swap the fan and headlight relays. Might be defective.
 

budwich

Well-Known Member
"The fan does kick on from time to time. Im at a loss for what to do next."
Get some OBD data reading / gathering capability and check the requested speed and resulting speed to see what's happening from the PCM's point of view.
 

Mooseman

Moderator
If the compressor clutch is slipping, you would see and hear it. That's why you need a full set of gauges to see what is really going on. There could be a blockage in the system or a failing compressor.

How was it fully charged? One of those cans with a gauge on it? This means nothing. It could still be over charged. I know of someone who had it filled at a shop and they overfilled it because they thought it was a dual system (like in an EXT) when in fact it was a single. Even shops screw up.
 

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