Rep Power: 197

Hey, again.

This has happened all winter, but now that temperatures here are hitting -35 degrees Celsius (-31 celsius) waking up and heating up my engine only to have it blow cold air at me is annoying.

So after 10 minutes of warming up, and another 10 minutes of driving, the car temp is finally hot enough for me to turn on the heat... or is it?

The problem i'm having is that even though the car is hot, i'm getting freezing cold air through the vents unless i'm going like 70km/h (approx 45 mph). If i'm driving at like 40 or 50 km/h i'm getting cold air through the vents. And even when i find myself going 80, when i get to a red light the air gets cold again, and it's another minute or two before it warms up again.

My cousins civic isn't the same way, when his engine is hot he gets hot air... so it's not all civics that do this (which i thought it was at one point). Any ideas?

 
Rep Power: 811

is your temp gauge showing normal? check behind the glove box see if its hot back there. if you turn the temp dial to cold, does the air get colder? do you hear any noises in the dash when turning the dial? do this when the car is ON but engine is not started.

 
Rep Power: 197

is your temp gauge showing normal? Yes
check behind the glove box see if its hot back there? I'll have to check in the morning
if you turn the temp dial to cold, does the air get colder? I haven't tested this, but i asked my dad and he said that it did
do you hear any noises in the dash when turning the dial? Just went out and checked, you can hear the vents or whatever changing ... yes there is noise

My dad just asked me to remind you that when i'm going fast enough the hot air comes out fine

 
Rep Power: 811

seems the temp dial is working, thats a bad sign. it means something is wrong with the cooling system. either clogged heater core in the dash or there is a problem under the hood. wait the fan is blowing normally right? like on high speed you have alot of air coming out but its just cold? is your coolant full in the overflow tank and in the radiator? make sure car is cold before opening radiator cap. does the temp gauge ever go back down when driving? when you are warming up the car, feel the upper and lower radiator hoses before you start driving (and before car warms up fully). the top hose should be hot and bottom hose should be ice cold. if bottom hose is hot or warm, your thermostat is stuck open and is constantly circulating the entire coolant supply thru the radiator. this makes it very hard for the engine to warm up and run efficiently, and can cause heater to have alot of problems getting warm air. normally thermostat should be closed until engine warms, then it opens slowly to let coolant out to cool off in the radiator. if its really cold outside, the thermostat may even close again if the coolant isnt warm enough.

 
Rep Power: 0

gearbox is right on the tsat but you said it heats fine when yu drive so its def more


its funny because im having the exact same problem, you said when you drive it blows warm..which is exactly what im experiencing right now

your problems are as follows:

bad tsat and a block heater core or simply air thats in your system,

going into your firewall is 2 hoses, they lead to your heater core, while your car is sitting and running for a while, turn your heater on and check the temps of the hoses by simply placing your hand on both, see if there exactly the same temp. if the one on the right is warmer than the one on the left. than your heater core is blocked and will need to be flushed. you can find videos on how to do it online or take it to your mechanic.. i plan on doing mine this weekend when i have time


change the tsat while your at it its cheap to do and is worth the time since your already under the hood.

make sure once you do all this top of your coolant again, and let the car run a little bit with the rad cap open to release any air that is in your system.

 
Rep Power: 197

Okay so i'll try things one at a time, and since replacing the coolant (which we haven't since we got the car a yr and a half ago ... and who knows when the previous owner changed it) seemed easiest my dad replaced it today. He said he thinks it made a difference but i'm going to check that out tomorrow morning b4 i go to work. If it doesn't work i'll take the next suggestion and get back to you guys!

 
Rep Power: 387

When its really cold I also notice what your describing, but its very minimal in my car and doesnt bother me enough for me to actually consider it a problem. I'm thinking its normal for our cars, but the lower the temp, the more obvious the issue.

 
Rep Power: 197

Well after changing the coolant the heat is working perfectly! Even when my engine is still sort of cold the heater is working perfect! I no longer have to wait 20 minutes and then go 60+ to get hot air lol. Thanks guys!

 
Rep Power: 811

interesting, maybe some stuff got pushed out that was causing clogs. new coolant by itself wouldnt matter.

 
Rep Power: 197

Honestly have no idea what happened but it's working now so i'm not complaining

 
Rep Power: 0

I'm having the EXACT same issues, only I'm sitting at about 10deg. I'll be flushing my system next time I have a buddy's garage to borrow and I'll have to look up videos on flushing the heater core.

Either way thanks for the thread

 
Rep Power: 312

Keep an eye on your coolant system now. I hate to say this but I don't think youve found the underlying problem unless it was a clog.

 
Rep Power: 0

Had a minivan giving me All kinds of the same problem, and tried everything, until I talked to a Semi-retired Mech in my street...Get yourself a jug of CLR, ya, the one on tv, pop the 2 hoses off that lead to the heater core, try and remove/blow out as much coolant as you can thru the hoses, and then fill the core with CLR, in one end until it starts coming out the other..(may want to do this in a driveway or something, it's nasty on painted floors, Just do it over the oil spill/stains in your driveway, kill 2 birrds with one stone..Anyhow, long story short..you SHould see some fizzing/foaming; that means it's working on the scale inside the core... Do it a couple times, clearing it out each time to just air, and then flush with a clean water hose..Until clear, backwards or forwards, whatever..then clear agaIN, FILL WITH STRAIGHT COOLANT, reattach the hoses, bleed out any air, and you SHould have heat like new..Said he had to do a Ford minivan 3 winters in a row, but it worked..(Hard water issues aside on that one..) Good luck!! Hope it helps, can't hurt!

 
Rep Power: 0

My 1997 civic:

• Hose on top is hot
• Bottom is cold
• Heater control valve hose is hot
• Outlet is hot (not as hot as inlet) at firewall

I flushed with water and air. I also used CLR, but only could get 8 or less ounces in; not sure about that issue.

based on the threads, I will change my thermostat, even though it shows normal operating temp on the idiot-guage.

Started to tear down the dash for the heater core, but will change the thermostat first - I was told that it is not the thermostat due to it showing normal range on the idiot-guage.

 
Rep Power: 284

Did you test the current thermostat?

 
Rep Power: 0

You really should never use anything other than distilled water to flush out cooling system parts. Drinking water has all kinds of impurities that can lead to corrosion.

 
Rep Power: 0

no I didn't due to people saying "if idiot guage come up to normal and stays, it is not the thermostat".

 
Rep Power: 0

[QUOTE=04blueem2;4514866]
going into your firewall is 2 hoses

Any chance you could tell me the inner diameter of those 2 hoses?

 
Rep Power: 223

This thread is nearly 8 years old.

The heater hoses are 16 mm (5/8 inch) inside diameter.

 
Rep Power: 511

lol, I saw "DarkSouljur" as the thread starter and though he started posting again XD

I'm friends with him on fb. Well, him and his cousin. I forgot whose screenname is whose.

 
Rep Power: 366

LOL, same here
Dark is S, A is the other (forgot A's Screenname )

 
Rep Power: 0

I'm new here. How do i post a question? Can someone please walk me through step by step directions.

 
Rep Power: 118

Did somebody else post that for you, or did you figure it out?