No heat at idle

[raven4life]

My car warms up from a cold start but when I drive and come to a stop cold air comes out but if I rev it or drive the heat is hot also the lower radiator hose is cold


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[08mzr]

In my expirence, 90% of the time is low coolant, 5% is air in the system because of a leak or recent cooling system repair, and 5% other.
Start with checking coolant level and be sure the system is properly bled a d that you have no leaks.
If it was a thermostat issue you would have poorish heat while driving.
With most owners never exchanging coolant as they're supposed to, replacing the thermostat is good maintenance, but dont expect it to fix you're issue.

[raven4life]

How would I bleed the system? And also the coolant reservoir is at the max amount


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[08mzr]

Have you had to add any coolant to it?
Bleeding is usually done by just letting the car run up to operating temp with the reservoir/radiator cap off. After it's up to operating temp let it run for a little while longer, revving it to 1500rpm during the warm up and running process helps circulate coolant.
After letting it run I like to turn the car off and let it sit without the cap on it until it cools and then repeat the process. I have had air escape a lot during the cool down proccess.
Some people like to jack the car up on just the side with the reservoir, but this is up to you.

[Thor Hammer]

Originally Posted by raven4life My car warms up from a cold start but when I drive and come to a stop cold air comes out but if I rev it or drive the heat is hot also the lower radiator hose is cold Sent from my iPhone using Tapatalk

You may have a faulty thermostat that's sticking. Or like stated, low coolant. I would drain and fill with new coolant, bleed, and go. Do not open the cap when the engine is hot as the system is under positive pressure!

[raven4life]

I haven’t added any coolant and never took the cap off. Just started to happen with it was -30 outside


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[Tomas]

At -30F I am not sure the thermostat will ever open. You know how cold that is nigga? Fuuuuuu.

[Jeff23spl]

to bleed it, you can lift the front higher than the back while doing the above instruction to help the bubbles to get out.

It can also be your heater core that is plugged with deposit when someone never replace the coolant. A flush with cleaning product may help but when it is too late, it means a core replacement....
Some leak fixing stuff is terrible at blocking heater core and some other part of the system...Never use that.

In the other hand, you may monitor your coolant temp, it takes a lot more time to heat up a car with a -30deg C outside...And when the turbo is used, you quickly feel the heat generated....

Our thermostat are likely to bloc at some opening position a bit more than usual. If you monitor an unstable temperature, it may return a bad TH. During very cold days, it is likely to get up to temp and then drop a bit while slowing down 1 or 2 times but if it keep going up and down when the car is up to temp for a long while, your TH is bad.....

I would start with a new TH, a coolant flush and new coolant perfectly bleeded. Then if it isn't better, i would investigate into a core replacement but it is usually a pita...

[MSMS3]

Originally Posted by 08mzr Have you had to add any coolant to it? Bleeding is usually done by just letting the car run up to operating temp with the reservoir/radiator cap off. After it's up to operating temp let it run for a little while longer, revving it to 1500rpm during the warm up and running process helps circulate coolant. After letting it run I like to turn the car off and let it sit without the cap on it until it cools and then repeat the process. I have had air escape a lot during the cool down proccess. Some people like to jack the car up on just the side with the reservoir, but this is up to you.

OP just do this outlined above. I call it "burping" the air out of the system. Same thing.

I just had to increase antifreeze to water concentration for winter. I was selling the car (my baby) to someone in a more frigid climate. I run a higher water ratio most of the year. I drained out about a gallon from the plastic plug in the bottom left side of the radiator and then began adding pure antifreeze and testing until I got the ratio to 50-50.

I left the cap off the reservoir, it did a lot, I mean a lot of burping of air before I got it all out. Had to leave it running quite a while with the cap off until the coolant level normalized. Turned it off, let it sit, watched the reservoir and then restarted it and ran it some more. As more and more air escaped I slowly topped off with a 50-50 solution until it stabilized at the proper level.

You may just have air in the system. Good time for a drain and flush if it's never been done, anyway.

Good luck.

[raven4life]

So I replaced the thermostat a couple days ago and the heat worked but my temps would go up on the high way and when I slow down/stop it goes down about 20 degrees. And just last night I got cold air at idle again


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[Jeff23spl]

have you bleeded it again after running for a while with the front leveled ?

I bet your belt was spinning fine around the pump so if the air is gone and TH is new, the only part remaining is a plugged heater core...

I would give few more try at bleeding it with enough temperature.
I cost nothing while replacing the heater core is a pita...

[raven4life]

It was good for a couple days after I bled it then again it happened today so I bled it and it’s good again. Also when my car is up in temp I see slight steam coming from the top of the rad could that be a hole? My coolant level hasn’t moved since


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[Jeff23spl]

sometimes you have some drops when filling the rad and it makes that but vanish after few days of driving. If it is dry outside and it keep smoking, yest you may have a leaking rad.