Hello.. I'm having a problem on my 05 civic with the heat coming out of my vents. When i warm-up my car in the morn it seems to warm-up as usual, But just recently when ever i stop my car (idling) for a period of time of more than a few mins. My heat seems to get colder out of my vents, But once i start driving again it heats back up hot again..

It's really messed up.. Once i drive around and check my radiator hoses, My upper radiator hose is hot and my lower is cold.. which is weird cause if it was the thermostat, the car would either overheat or not be warmed up at all???

I'm going to check the coolant in the morn i think it may be low.. Any suggestions?

Thanks in advance

 

If there's no coolant flow it's one of the following:
1. thermostat
2. air pocket
3. coolant blockage

My suggestion is flushing the system, and properly venting the air bubbles.

 

Thanks Matt

 

Hmm.. I would that to say you need a Thermostat might be a little on the extreme side. I had one of these not too long ago on an 05 Civic too. I allowed the vehicle to warm up in the shop and then drove it. Came back and the heat coming out of the vents were around 70F and the lower radiator hose was still cool. I suspected the thermostat, so I revved the car at 2500 rpm until the fans came on, which signified to me that the thermostat was working.

Then I checked the heater hoses at the firewall. I found the inlet hose was hot on both side of the heater valve which proved that the valve was working and that the heater core was getting hot coolant.

Then I checked the outlet hose from the heater core, it felt cool. So I narrowed it down to a restriction in the heater core. I checked the coolant in the overflow and found that it was way over protected and looked a little gooey. I then pulled the outlet hose at the heater core and found that there was no flow.

I proceeded to remove both hoses at the heater core and blew it out with air and found chunks of "Stop Leak" in it. Then I ran water through the core and got it free flowing both directions. After that I removed the bypass hose and flushed it too because I didn't want any of that gunk stuck in the heater valve.

So yeah, to sum it up. I found a restriction in the heater core through diagnosis and not parts replacing.. Just remember to properly bleed the cooling system. Those vehicle are notorious for air pockets.

 

Thanks for the info.. I'm most likely going to get it flushed this weekend.. The stealership wants $125 to do it.. but i think ill save the $100 and do it myself


Thanks for your opinions and similar problems. I just didn't wanna buy stuff that i wouldn't need

 

waterpump

 

i have the same problems you do, but with a k-swap. car is parked until spring so by then i wont even need heat. haha.

 

EM2ner, My brother is having the same problem in his civic. It just started yesterday. Same problem where the heat works fine when the car is moving, but as soon as you stop it starts blowing cold air into the car. Let me know if you find anything out. Thanks

 

Same problem here in my 01 coupe

 

i changed my thermostat this morning and that seems to have fixed the problem for me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicEXSE05 &raquo;</TD></TR><TR><TD CLASS="quote">I am being told that I need a new heater core in my car because there is some sorta "blockage" in it which I thought was weird in a 2005 civic. I've had the system flushed, checked for leaks,etc. All they can come up with is a new heater core. Soooo I will let yah know after this Thursday if that works. </TD></TR></TABLE>

I would have them flush the heater core first. It's possible that it just has some fluid block in it. I've had to flush my heater core, due to a block, as has quite a few other members.

 

They tried to flush my heater core and couldn't remove the blockage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicEXSE05 &raquo;</TD></TR><TR><TD CLASS="quote">They tried to flush my heater core and couldn't remove the blockage.</TD></TR></TABLE>

That's a pain. Did they flush the heater core separately from the coolant system? That's what I ended up doing.

 

wow! I have the same freekin problem...I just deal with it by wearing my ski jacket...and Im fine!

so if I continue to use my car without fixing this issue...will it cause further damage in any way?

 

If whatever is blocking the heater core ever becomes "unblocked" it could recirculate through your nice clean coolant and contaminate it. And if left untreated, I could see it possibly causing some problems.

Just my educated guess on the matter...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nighthawk7thGen &raquo;</TD></TR><TR><TD CLASS="quote">wow! I have the same freekin problem...I just deal with it by wearing my ski jacket...and Im fine!

so if I continue to use my car without fixing this issue...will it cause further damage in any way?</TD></TR></TABLE>

It can, yes. A part of the blockage could dislodge itself and wind up destroying your head gasket, which can be a pain to replace.

 

yeah had the same symptoms and ended up witha blown head gasket numerous people did a few months ago act.

 

*Update* I got the car looked at from honda. At first they couldn't Figure out the problem but then they did a leakdown test and came up with a Blown Head Gasket. But it was covered under the warranty thank god . They had to mill it down cause it was slightly warped..