You could have a bunch of air in the lines or in the radiator and it can't fully circulate once the flow starts due to an air pocket. Do you hear any gurgling of the water anywhere? When my heater module was replaced I heard a lot of gurgling and then had to top off the fluid a few days later. Is your fluid tank full or has it dropped down and you have not yet noticed it has gone low? Make sure you set the heat to max high temp and fan on high so that it has a chance to fully heat/circulate too. If that doesn't sort it out, you may need to vacuum fill it or look for some other place where it may be getting blocked such as the 3 way diverter valve (which sounds like the only part you have not replaced).
Heat Problems - 2012 Volt
HELP with HEAT!
Hey friends, I'm having issues with heat in my 2012 Volt.
Originally started a while back with the heat becoming intermittent. I read all I could on DIY heat repairs and did a few things, cleaning that little inline filter, replacing the circulating pump down by the front right wheel, etc.
Couldn't figure it out or fix it.
I ended up taking it to the dealer service center, where they had it for the better part of a month. After poking at it for a while, they said I needed a new heater core. I agreed to have them put it in (even though it was overpriced) because they already had all that time sunk into it, and it was supposed to fix the problem. I would be happy just to have it fixed and have a working car again.
After that repair, which did NOT fix the heat problem, they said I ALSO needed a new electric heater! They wanted WAY too much money for that.
So I brought the car home, and have slowly been working on doing the electric heater replacement myself. I can't believe how much work it was! I now have a used electric heater in the car and have it all back together.
However...
I'm still having trouble with the heat.
But, since I have that new heater core in there and don't have the plastic cover over it yet, it's right where I can see and feel it while driving.
What's happening now is that the heat will come on for a bit. (I can actually see the heat indicator saying ON on the HVAC display screen) and the heater core will get hot, BUT the air coming out of the vents is either only warm or somewhat hot, but then turns cold after only a few minutes.
The heater core itself will usually still be warm. It's like the heater is running, but the fan is drawing air from somewhere other than through the heater core.
Heat does NOT work while running on engine power.
Air conditioning works fine.
Seems like it's perhaps just an issue of how heat is routed around? How would I troubleshoot this?
Thanks in advance!
![Automotive tire Hood Motor vehicle Automotive lighting Bumper]()
Hey friends, I'm having issues with heat in my 2012 Volt.
Originally started a while back with the heat becoming intermittent. I read all I could on DIY heat repairs and did a few things, cleaning that little inline filter, replacing the circulating pump down by the front right wheel, etc.
Couldn't figure it out or fix it.
I ended up taking it to the dealer service center, where they had it for the better part of a month. After poking at it for a while, they said I needed a new heater core. I agreed to have them put it in (even though it was overpriced) because they already had all that time sunk into it, and it was supposed to fix the problem. I would be happy just to have it fixed and have a working car again.
After that repair, which did NOT fix the heat problem, they said I ALSO needed a new electric heater! They wanted WAY too much money for that.
So I brought the car home, and have slowly been working on doing the electric heater replacement myself. I can't believe how much work it was! I now have a used electric heater in the car and have it all back together.
However...
I'm still having trouble with the heat.
But, since I have that new heater core in there and don't have the plastic cover over it yet, it's right where I can see and feel it while driving.
What's happening now is that the heat will come on for a bit. (I can actually see the heat indicator saying ON on the HVAC display screen) and the heater core will get hot, BUT the air coming out of the vents is either only warm or somewhat hot, but then turns cold after only a few minutes.
The heater core itself will usually still be warm. It's like the heater is running, but the fan is drawing air from somewhere other than through the heater core.
Heat does NOT work while running on engine power.
Air conditioning works fine.
Seems like it's perhaps just an issue of how heat is routed around? How would I troubleshoot this?
Thanks in advance!
1 - 15 of 15 Posts
I got up under the driver's side dash by the accelerator pedal.
Only one screw holds the feet heater vent in place there. That was easy to remove. With it out of the way, I could better see the temperature blend door actuator.
Two screws and two alignment pins hold it in place. After removing both screws, it was easy to pull away from the housing.
I first wanted to confirm that it was the temperature control NOT the recirculate/fresh Air control. I had an assistant turn the RECIRCULATE button on and off a few times. Nothing happened.
Then I had her turn the temperature control way up and way down. The drive shaft on the actuator MOVED! Which seems to me that it should be working.
I stuck a screwdriver in the recess that the actuator goes into and turned it. I could feel the temperature flap open and close.
With the car powered up, blower on, heat on, heater core hot, I flipped the flap the other direction.
I STILL got COLD air coming out of the vents!
How is that even possible?
This project is driving me crazy!
![Hand Automotive tire Finger Thumb Hood]()
![Vehicle Automotive tire Hood Motor vehicle Automotive design]()
Only one screw holds the feet heater vent in place there. That was easy to remove. With it out of the way, I could better see the temperature blend door actuator.
Two screws and two alignment pins hold it in place. After removing both screws, it was easy to pull away from the housing.
I first wanted to confirm that it was the temperature control NOT the recirculate/fresh Air control. I had an assistant turn the RECIRCULATE button on and off a few times. Nothing happened.
Then I had her turn the temperature control way up and way down. The drive shaft on the actuator MOVED! Which seems to me that it should be working.
I stuck a screwdriver in the recess that the actuator goes into and turned it. I could feel the temperature flap open and close.
With the car powered up, blower on, heat on, heater core hot, I flipped the flap the other direction.
I STILL got COLD air coming out of the vents!
How is that even possible?
This project is driving me crazy!
1 - 15 of 15 Posts
