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Hello, all.

This is my first post on these forums as it seems to be a pretty thorough resource for Colorado owners. I own a 2008 Colorado, 170k miles, I5 3.7L. She's been pretty good to me until this year when it started overheating. It started back in the summer so I replaced the thermostat and flushed the radiator, standard procedure. It helped, but didn't completely rid it of the overheat. Fast forward to about a month ago, and the overheat is now pretty bad, as in now I can't drive any more than 30 minutes before I'm hitting red. I can smell coolant leaking and in the picture included in this post, I get a good spillage from the "weep hole" positioned below the heater core, making me think my heater core is shot. On top of the overheat, the blower stopped working in the cabin (more on that in a second). I took the car to the dealership for a diagnostic and they said 1) my fan clutch was toast and 2) the blower motor AND resistor was bad. After offering to repair it for $1300, I said "No thanks" and immediately purchased a new fan clutch and installed it. Again, the problem got better but it did not completely fix the issue, it just slowed down the amount of time it took for it to overheat.

Now, about the blower motor/resistor.... I've heard they can burn out due to a bad ground. The other day when it overheated very badly before I could park it to cool off, I got the alert "AC OFF" on the dash.... But my A/C hasn't been on in weeks since the blower stopped working... This got me thinking: "What if there is a bad current to ground from the AC compressor, causing it to 'be on' without really being on and in fact is seized, putting a greater load on the belt system and not allowing the fan/water pump to spin freely?" This is further buttressed by the fact that I have noticed that if I were to turn the defrost on with my blower motor off, the A/C line ices up... A seized AC compressor could cause condenser failure/radiator failure/increased load on the serpentine system...

There is a shit ton going on here but I am at a loss for where to go now. It seems it could be anything I've described and I need a course of action... Thank you all in advance, and if this has been remedied in another post please tag me in it.

Yours,
SlickWilly69
 

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View attachment 343217 Hello, all.

This is my first post on these forums as it seems to be a pretty thorough resource for Colorado owners. I own a 2008 Colorado, 170k miles, I5 3.7L. She's been pretty good to me until this year when it started overheating. It started back in the summer so I replaced the thermostat and flushed the radiator, standard procedure. It helped, but didn't completely rid it of the overheat. Fast forward to about a month ago, and the overheat is now pretty bad, as in now I can't drive any more than 30 minutes before I'm hitting red. I can smell coolant leaking and in the picture included in this post, I get a good spillage from the "weep hole" positioned below the heater core, making me think my heater core is shot. On top of the overheat, the blower stopped working in the cabin (more on that in a second). I took the car to the dealership for a diagnostic and they said 1) my fan clutch was toast and 2) the blower motor AND resistor was bad. After offering to repair it for $1300, I said "No thanks" and immediately purchased a new fan clutch and installed it. Again, the problem got better but it did not completely fix the issue, it just slowed down the amount of time it took for it to overheat.

Now, about the blower motor/resistor.... I've heard they can burn out due to a bad ground. The other day when it overheated very badly before I could park it to cool off, I got the alert "AC OFF" on the dash.... But my A/C hasn't been on in weeks since the blower stopped working... This got me thinking: "What if there is a bad current to ground from the AC compressor, causing it to 'be on' without really being on and in fact is seized, putting a greater load on the belt system and not allowing the fan/water pump to spin freely?" This is further buttressed by the fact that I have noticed that if I were to turn the defrost on with my blower motor off, the A/C line ices up... A seized AC compressor could cause condenser failure/radiator failure/increased load on the serpentine system...

There is a shit ton going on here but I am at a loss for where to go now. It seems it could be anything I've described and I need a course of action... Thank you all in advance, and if this has been remedied in another post please tag me in it.

Yours,
SlickWilly69
Welcome to the Nation
1. If the A/C is operating there should be clear water coming from that drain. How much comes out will depend on the humidity of the air entering the system. If the liquid you see is antifreeze, then you most likely have a heater core leak. If it is leaking a lot, that most likely is contributing to your overheat issue. Disconnect the hoses at the firewall and connect them together with a piece of tubing. That will confirm if the heater core is leaking. Other components that can cause overheating are water pump, radiator cap, and insufficient antifreeze in the coolant.

The HVAC blower is relatively reliable and most problems with it involve the resistor. The wiring at the resistor connector has a tendency to overheat and melts the connector and wiring. Yes, the ground points in the engine compartment have a history of causing electrical problems. At a predetermined high engine temperature the PCM will automatically shut down the compressor and display "A/C Off" in the cluster. It probably doesn't care if the A/C is on or off and will trigger the notification regardless.

The problem with the A/C compressor operating with the blower switch off will require some troubleshooting. With the A/C button "OFF" and the fan switch "ON", the compressor will automatically operate with the mode select in either of the defrost positions. So, the fact that the compressor is operating with the mode in defrost is normal. It just should not operate anytime the blower switch is "OFF".
 

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Discussion Starter · #3 ·
Welcome to the Nation
1. If the A/C is operating there should be clear water coming from that drain. How much comes out will depend on the humidity of the air entering the system. If the liquid you see is antifreeze, then you most likely have a heater core leak. If it is leaking a lot, that most likely is contributing to your overheat issue. Disconnect the hoses at the firewall and connect them together with a piece of tubing. That will confirm if the heater core is leaking. Other components that can cause overheating are water pump, radiator cap, and insufficient antifreeze in the coolant.

The HVAC blower is relatively reliable and most problems with it involve the resistor. The wiring at the resistor connector has a tendency to overheat and melts the connector and wiring. Yes, the ground points in the engine compartment have a history of causing electrical problems. At a predetermined high engine temperature the PCM will automatically shut down the compressor and display "A/C Off" in the cluster. It probably doesn't care if the A/C is on or off and will trigger the notification regardless.

The problem with the A/C compressor operating with the blower switch off will require some troubleshooting. With the A/C button "OFF" and the fan switch "ON", the compressor will automatically operate with the mode select in either of the defrost positions. So, the fact that the compressor is operating with the mode in defrost is normal. It just should not operate anytime the blower switch is "OFF".
So you're saying that the blower motor might not be bad at all and it's just the resistor? Like I said, the dealership said it was both. Unless they're just trying to get my money... 🙄
 

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So you're saying that the blower motor might not be bad at all and it's just the resistor? Like I said, the dealership said it was both. Unless they're just trying to get my money... 🙄
Try operating the blower on high speed. The high speed circuit bypasses the resistor module. Or you could apply 12v to the blower. The Brown wire in the connector is + and the Orange wire is - . Would I suspect a Dealer? You bet, I would.
 

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So you're saying that the blower motor might not be bad at all and it's just the resistor? Like I said, the dealership said it was both. Unless they're just trying to get my money... 🙄
One other thing comes to mind regarding the blower. If the liquid that you see coming from the evaporator drain is, in fact coolant, that means that the coolant could also be puddling in the bottom of the HVAC case and getting into the blower motor. That drain is supposed to be just for the evaporator. Probably a good assumption that the Dealer didn't remove the blower for troubleshooting. Any sign of wet carpet in the area?
 

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Regarding the leaky heater core...this "Fix" is still holding up for me after 4+ years. Beats the hell out of removing the dash!

 

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Discussion Starter · #7 ·
One other thing comes to mind regarding the blower. If the liquid that you see coming from the evaporator drain is, in fact coolant, that means that the coolant could also be puddling in the bottom of the HVAC case and getting into the blower motor. That drain is supposed to be just for the evaporator. Probably a good assumption that the Dealer didn't remove the blower for troubleshooting. Any sign of wet carpet in the area?
The dealer definitely did not remove the blower motor for troubleshooting...
 
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