2010 Taco Heater Problems

Hey there fellow taco owners, I have an interesting issue going on with the heater in the truck that has me stumped. I have read some other threads in here on heater issues, but I do not think that I am having any of those issues like a head gasket going out, or climate controls. I hope. Lol

So here is the problem; When I accelerate or get the engine over 1500 rpms I have nice hot air coming out of the vents, as soon as I stop at a stoplight or slow down in traffic the air cools almost to fully cold. Does it when I am driving or in park, whether recirculating or bringing in outside air, and I have full air flow coming out of the vents. I also do not think it is anything with the climate control flaps or mechanism as it seems to switch to full cooling if I turn the dial all the way into the blue. Engine is cooling perfectly, the temp gauge stays in the middle where it always has and never fluctuates outside of a slight bob up and down when I am idling the engine at or above 1500 rpms trying to get the heat to get hot while in park. I checked the hoses going into the heater core on the drivers side and the top hose is almost too hot to touch, while the bottom hose is just warm. After idling up to 1500 rpms the bottom hose gets hot but as soon as I let the engine idle back down to 500-700 it turns just warm again. It also seems if I pinch the top hose a few times the bottom hose will heat up briefly.

I have burped the radiator twice, I have also disconnected the two hoses from the heater core and flushed through it with water using a garden hose and a jet nozzle. No gunk came out when I did this, and nothing but a couple small bubbles when I burped the system. No constant bubbling though so I hope it is not the head gasket. Took it to the dealership for troubleshooting, they checked the water pump bearings and all over for leaks and found nothing. Had the truck for two days to tell me that. Lol. Their next suggestion was to flush the cooling system (which they have already done about 7 months ago) I told them no as I do not think that will help. The weather was warm when they did the flush but in the few times I have used the defrost or heater since then I think it was working correctly as far as I know. Just never noticed this problem until the weather got cold within the last few days. We just had our first snow and freeze here in Denver.

I am not all that mechanically inclined so any insight into this would be greatly appreciated. Thanks!

 

could it be the actual heater core?

 

I am not too sure, I have not pulled apart the dash and all that to check just yet. Maybe it got pinched somehow blocking full flow?

 

That is a classic symptom of an air bubble trapped in the system. When did this happen or start? Was it after a drain and flush?

Park with the nose elevated as much as possible ( on a hill etc ). Warm up the truck to operating temperature and massage the upper radiator hose with the radiator cap off.

 

I noticed it months after the drain and flush. Far as I know all worked well until the last week or so.

I've burped the system three times now, two of the three the truck was sitting at about a 35 degree angle on a hill. I did notice tonight though after running it for over an hour doing the burping, and driving home for 45 minutes the hose coming out of the bottom of the radiator was still cold. Shouldn't that be at least warm to hot? Would a sticking tstat in the radiator system cause flow issues in the core as well?

 

Oh and each time I also added a small amount of coolant and messaged the top radiator hose. After the core flush I did get quite a bit of air that came out. Only a few little bubbles the third go round though. Each time I ran the rpms up anywhere from 3 to 5k intermittently to help the water flow.

 

I would say that if the thermostat was sticking open the engine would not come up to proper temperature. If it was stuck closed it would overheat.

 

Good point. I am totally out of ideas, unless I am not burping the system correctly.