My cabin Heater is blowing cool/cold. I've checked and filled the reservoir and radiator. Any other ideas? Faulty Temp sensor in cabin? Anyway to bleed off the heater core?
Thanks

 

I would flush the heater core

 

Could very well be clogged, are either of the hoses that run to it hot. If one is hot and the other a lot cooler that is your problem.

You can try a flush of the heater core, water both ways it will also tell how bad it is. Some people have used the CLR product in there to try and loosen and break down the scale to avoid removing it.

Pinch the hoses to keep the coolant in the rest of the system
Remove the hose clamp and and both hoses
Run water in from a garden hose the water coming out should be a pretty solid stream
If it is not switch hoses

If it is still bad you should really replace it, but if you want to try the CLR method

Try to blow as much water out as you can with compressed air
Restrict the output of one hose by pinching it
Pour the CLR into the other hose until it comes out
Leave it for NO Longer than 15 minutes it is corrosive
Have a bucket to catch what comes out - you want to see if any material comes out
Flush the heater core for a good 15 minutes each way with water
If the flow is better or much improved you have bought yourself some time
You can repeat this process a few times if your flow improves

But it is absolutely important the you flush that heater core thoroughly before putting everything back together a good 30 minutes you do not want any of that stuff left in the system

 

If all of the coolant/heater core issues are solved and working another possible cause is that the servo and flap that mix heated air and cold air are stuck in the "cooling" position. If it's a faulty cabin temperature sensor in the you can "override" this by turning the heat all the way up to maximum (HI) and the system will heat as much as it can regardless of cabin temperature.