Pontiac G8 Forum banner

1 - 20 of 41 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter #1
I’m unable to get my coolant fans to come on. I checked all related fuses and did relay swaps. I checked and topped off coolant. I can’t seem to pinpoint my issue. I’ve tried turning on my ac (which isn’t blowing cold either) but still no coolant fan action. I’ve went to engineer mode and let the car sit and idle (twice) to try and get the temp up but it’ll get up to 105 then gradually go back down. I tried one thing I remember doing in my other car and disconnected the coolant temp sensor then both fans automatically came on. I got a “SEE DEALER” warning but that assured me that the actual motor in the fans weren’t out. Could it be my thermostat even though I’m not overheating?? Any help, tips or suggestions would be greatly appreciated.
 

·
Registered
Joined
·
2,299 Posts
Grab a volt meter, looking for 12v starting at fan connector
 
  • Like
Reactions: JodyG8

·
Registered
Joined
·
4,460 Posts
Let’s rule out the thermostat as part of the problem. Start the car cold and check to see if the coolant is moving in the rad. If it does the thermostat is stuck open and needs to be replaced. Now the engine can reach operating temp and see if the fans come on.
 
  • Like
Reactions: JodyG8

·
Premium Member
Joined
·
6,697 Posts
Start the car. Let it run for a few minutes. Turn the heater to the highest temperature setting. Turn on the blower motor and see if the air is hot. By the way, one radiator fan should start soon after the air conditioner compressor is commanded on whether the air is cold or not. Presuming the power-train relay (R13) is functional, then check the emission 2 fuse (F32).

Pontiac G8 (2009) - fuse box diagram - Auto Genius
 

Attachments

·
Premium Member
Joined
·
6,697 Posts
By the way, were any repairs recently made to the vehicle?
 

·
Registered
Joined
·
27 Posts
Discussion Starter #7
Start the car. Let it run for a few minutes. Turn the heater to the highest temperature setting. Turn on the blower motor and see if the air is hot. By the way, one radiator fan should start soon after the air conditioner compressor is commanded on whether the air is cold or not. Presuming the power-train relay (R13) is functional, then check the emission 2 fuse (F32).

Pontiac G8 (2009) - fuse box diagram - Auto Genius
Fan for the heater was hot. I plan to check the F32 & R13 tomorrow morning. Don’t have any movement from the fans with the ac on. I’m wondering if the gauge is not accurate and it’s low or the compressor has failed.
 

·
Premium Member
Joined
·
6,697 Posts
The heater being hot indicates coolant is flowing throughout the system. Went back and read disconnecting the coolant temperature sensor wiring harness caused both fans to activate. As a result, can disregard the second half of post #4. Could be a faulty/erratic coolant temperature sensor since the temperature goes up to 105 and then falls. When the air conditioner is activated does the snowflake emblem's light remain lit (manual climate)? Remain lit or flicker on the screen (automatic climate)? Verified the refrigerant level?
 

·
Registered
Joined
·
27 Posts
Discussion Starter #9
The heater being hot indicates coolant is flowing throughout the system. Went back and read disconnecting the coolant temperature sensor wiring harness caused both fans to activate. As a result, can disregard the second half of post #4. Could be a faulty/erratic coolant temperature sensor since the temperature goes up to 105 and then falls. When the air conditioner is activated does the snowflake emblem's light remain lit (manual climate)? Remain lit or flicker on the screen (automatic climate)? Verified the refrigerant level?
I forgot to mention that after I got the coolant fans to turn on by unplugging the coolant temp sensor I immediately went to my parts store and picked one (CTS) m up and installed it in hopes of that being my problem. This morning I have replaced the thermostat and refilled with antifreeze and nothing has changed. It’ll get up to 105 then drop again from the engineer screen. I’ve checked the refrigerant with the parts store can/gauge (2 different ones) they both read that the system was “in the red” and I’m afraid to add any and mess something up further. The car isn’t over heating via the gauge but I’m unsure where else to check
 

·
Premium Member
Joined
·
6,697 Posts
Probably a moot point, but which brand of coolant temperature sensor was used? Thermostat? Have you inspected the coolant sensor's wiring harness? Be sure to properly bleed the system of air, Bleeding my cooling system of air. Per my understanding, those refill kits aren't very accurate and was thinking along the lines of checking the level (charge) with a professional set of gauges.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #11
Probably a moot point, but which brand of coolant temperature sensor was used? Thermostat? Have you inspected the coolant sensor's wiring harness? Be sure to properly bleed the system of air, Bleeding my cooling system of air. Per my understanding, those refill kits aren't very accurate and was thinking along the lines of checking the level (charge) with a professional set of gauges.
Duralast on both parts. Inspected wires, they seem to be in good shape. I’ve bled/burped the coolant system real good. I’m just lost at this point. I’ll have to wait until tomorrow to have some professional gauges popped on the ac system. The most recent things done to the vehicle other than an oil change last month was 3.27 diff upgrade (Jan. 9th 2021) & headers plus full exhaust (April 30th 2020). I don’t drive it much because I want to keep it in as nice of condition as possible while continuing to mod it. I vaguely remember before winter having my ac blow warm on start up and then either after I toggled with it for awhile or after driving a little while it would begin to blow cool. I still don’t understand why my temp wouldn’t rise and fans kick on regardless of the ac... I really appreciate your help PONY MAN
 

·
Premium Member
Joined
·
4,504 Posts
Hears the deal >>>> There are 2 speeds for the engine cooling fans. Both fans run at low speed, or both run at high speed. To get those fans to even run at low speed, your engine coolant has to exceed 219 F and or the A/C has been commanded to run, an the high side pressure exceeds 220psi. The car will switch the fans over to high speed if the engine coolant temp were to continue to rise above 228 F , and or A/C high side pressure were to rise above 290 psi.
If your engines coolant system is so efficient that the temp never reaches that 219 F threshold or the A/C high side pressure never reaches 220 psi, those fans will not turn on unless you had some type of tuning done that would allow you to override those preset values. Since it reads like you cannot make cold air, an your engine coolant temp gauge apparently does not move up near the red zone, I can see why your fans never turn on.
If your positive your compressor belt is still spinning the compressor, my take is that you've lost most if not all of your refrigerant, or the electronic control valve in the compressor is not moving as it should to change the cold air demand requested (or worst case), the compressor took a dive on you. I ended up slowly loosing my refrigerant due to a leak from the high side pressure quick connect Shreader valve. An unless your staring at it (with the dust cap off) an see it bubbling, you would never know it was happening.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #13
Hears the deal >>>> There are 2 speeds for the engine cooling fans. Both fans run at low speed, or both run at high speed. To get those fans to even run at low speed, your engine coolant has to exceed 219 F and or the A/C has been commanded to run, an the high side pressure exceeds 220psi. The car will switch the fans over to high speed if the engine coolant temp were to continue to rise above 228 F , and or A/C high side pressure were to rise above 290 psi.
If your engines coolant system is so efficient that the temp never reaches that 219 F threshold or the A/C high side pressure never reaches 220 psi, those fans will not turn on unless you had some type of tuning done that would allow you to override those preset values. Since it reads like you cannot make cold air, an your engine coolant temp gauge apparently does not move up near the red zone, I can see why your fans never turn on.
If your positive your compressor belt is still spinning the compressor, my take is that you've lost most if not all of your refridgerent (or worst case), the compressor took a dive on you. I ended up slowly loosing my refridgerent due to a leak from the high side pressure quick connect Shreader valve. An unless your staring at it (with the dust cap off) an see it bubbling, you would never know it was happening.
I’ve seen slight bubbling there before I believe. Is it on the driver side close to the radiator? It even has some black sutt around the valve as if it may have collected dust from leaking fluid. What was your the fix for the leak?
 

·
Premium Member
Joined
·
4,504 Posts
I bought a replacement Shreader valve for that high side pipe from O'reilys auto parts. I know they say it requires a special socket (8 sided or something like that ?) to remove an replace. But NO, you can easily replace it with a pair of vice-grips an a knuckle buster wrench. Then added about 15 oz of refrigerant an good to go. Not the right way to do it, but OK for know. Since I've had to bypass the steering cooling function of the condenser (due to leaking). I'll do it right when I change out the condenser. Can't bring myself to do it at this time since the A/C still works quite well. From memory, the part I bought was the Dorman valve # 800-955 for about $ 9
 

·
Registered
Joined
·
27 Posts
Discussion Starter #15
I bought a replacement Shreader valve for that high side pipe from O'reilys auto parts. I know they say it requires a special socket (8 sided or something like that ?) to remove an replace. But NO, you can easily replace it with a pair of vice-grips an monkey wrench. Then added about 15 oz of refrigerant an good to go. Not the right way to do it, but OK for know. Since I've had to bypass the steering cooling function of the condenser (due to leaking). I'll do it right when I change out the condenser. Can't bring myself to do it at this time since the A/C still works quite well. From memory, the part I bought was the Dorman valve # 800-955 for about $ 9
After replacing the valve did your low pressure side still read high? I’m trying to figure out how to recharge the system. I just add it to the low pressure side? At the moment it reads high
 

·
Premium Member
Joined
·
4,504 Posts
I'm not an expert with the A/C system, but these are the things I've read about an have seen with what little time I've messed with this stuff. If you have the A/C set that reads low an high psi at the same time, I can tell you that both sides should/will read the same based on ambient temp, an everything is at the same overall temp (as in the morning before the engine an A/C are fired up). With ambient temp of about 70 F the low side would be around 30 to 35 psi. A can of refrigerant will/can be drawn into the system, but works a lot better if the A/C is running If your static (or with A/C running) low side psi reading is a lot higher than above, I think that is an indication of some internal problem within the system.
 

·
Premium Member
Joined
·
6,697 Posts
Approximate air temperature? Does the temperature gauge start at cold and gradually increase before dropping? Was the car tuned after the headers installation? When the air conditioner is activated does the snowflake emblem's light remain lit (manual climate)? Remain lit or flicker on the screen (automatic climate)? By the way, correct operation of the coolant temperature sensor requires a good ground connection perchance to its mating surface. If so, the surface should be free of corrosion. Starting to wonder if there could be a shortage somewhere. :unsure:
 

·
Registered
Joined
·
27 Posts
Discussion Starter #18
Approximate air temperature? Does the temperature gauge start at cold and gradually increase before dropping? Was the car tuned after the headers installation? When the air conditioner is activated does the snowflake emblem's light remain lit (manual climate)? Remain lit or flicker on the screen (automatic climate)? By the way, correct operation of the coolant temperature sensor requires a good ground connection perchance to its mating surface. If so, the surface should be free of corrosion. Starting to wonder if there could be a shortage somewhere. :unsure:
Air temperature has been between 55-65 while working on it. Yes the temperature gauge starts low via needle and engineer mode then gradually rises up to only 105 then gradually drops back as low as 95 after running for approximately 15-20 mins. The car had rear O2s deleted and dod turned off but no performance “tune”. I’ve recently been getting an intermittent P0131& P0171 code as well. There’s no flickering of the snowflake after turning on ac I can’t remember if it was in manual or automatic. I’m still curious to know what my issue is but I dropped it off at the shop this morning feeling defeated because I haven’t been able to figure it out...😤 should know something in the next couple of days.
 

·
Premium Member
Joined
·
6,697 Posts
Those two codes P0171 and P0131 may correlate to the driver's side upstream oxygen sensor.
 

·
Registered
Joined
·
27 Posts
Discussion Starter #20
Those two codes P0171 and P0131 may correlate to the driver's side upstream oxygen sensor.
I’ve ordered some but initially I thought maybe it was an exhaust leak. Took it to a different exhaust shop than who did the header and we found a couple of spots that were slightly leaking. Patched em up and went about my business. Went about 3 days without the code again then it popped up this morning.
 
1 - 20 of 41 Posts
Top