[Stuart Dalton]

I'm not getting any cabin heat in my 2000 Insight. 3 weeks ago the heat disappeared for 10 minutes during a long drive but then came back on for the rest of the trip. After that the heat disappeared for longer and longer periods until now there's no heat at all. I've replaced the thermostat, done the burp procedure very carefully, checked the valve to the heater core (it works fine) and back flushed the heater core (there was no sign that the core had been clogged). The little motor that opens the valve to the heater core works fine--I can see it moving--and the blower works fine, just no heat. At this point I can't think of anything else I can do short of removing the heater core unit, which obviously I want to avoid since it involves first removing the dash. Am I missing anything? Is there anything else I can try before removing the heater core? Thank you for your time and your suggestions.

 

[UK_MJN]

Hi Stuart.

I started a thread here with a similar issue recently, reporting no cabin or screen heat for the first 9 miles on a cold day, and then experienced a serious over-heating incident on the next drive. The car is now off the road with a diagnosed head gasket failure and blocked radiator. In my opinion your concern is sensible.

It's been difficult to establish exactly what exactly happened to our 2000 car, but the best ideas from the guys at the Honda garage and the mechanic who recovered the car are:

1. Poor coolant condition allowed partial freezing and head gasket damage, leading to loss of coolant into engine and drop in coolant level, leading to thermostat and cabin/screen heater problems. Radiator also end of life.
2. Blocked radiator in cold weather preventing circulation, leading to thermostat and cabin/screen heater not operating (when cold) followed by localized boiling and head gasket failure (when hot).

So I suggest checking the coolant level/condition. If it is low (and no leaks) then you might have #1. If you get the radiator checked/flushed then you can rule out #2. In our case the heater and water pump are thought to be working fine.

Hope that gives you some more ideas!

 

[talonmike]

Check for the coolant valve. I am pretty sure it is sticking. Maybe the lever is broken and the valve itself does not move?

Did you check if the heater hoses get hot?

 

[Stuart Dalton]

Thanks for the suggestions. I did check the valve where the coolant enters the heater core, and also the coolant and cooling system condition generally. The cooling system was just serviced last summer and new coolant added. It's all in good condition. The cabin heat occasionally comes back for a few minutes--never very warm though--but then disappears again. I thought everything pointed to a blocked heater core, but that wasn't the case. If anyone else has any ideas I'll be grateful for them. Thanks

 

[BOMBCRU]

I just went through this 2 times this year.... both times after a long road trip

First time the thermostat was fubared after 1 year being replaced.

Second time I went from 90 to 70 cuz the gf was to hot, when she said she was cold, I turned it back to 90 and it stayed cold....

After 45 minutes I got it home, started messing around, the valve before the heater core was stuck closed, eve with thermo on 90*. I manually opened the valve( was tough) and i got my heat back instantly.

You could also have air in the heater core still. After I did my thermostate, I drove around a day and lost heat again and car got hot, right after running it hard on the highway. I burped it/ refilled and was fine, just a idea.

 

[AbCaRed00]

I thought everything pointed to a blocked heater core, but that wasn't the case. If anyone else has any ideas I'll be grateful for them. Thanks

Could be a block of air in the coolant system. When the coolant was added likely via the radiator cap at a change, was the air purged from the system?

Since the rad cap's lower than the highest point of the Insight's coolant system, air purging is required after a change; topping up the coolant system afterwards should be accomplished via the overflow container, where the level is checked.

 

[Willie Williford]

When changing coolant always "burp" the engine with the heater on and the temp. set at the highest setting with the fan on high.

Just a reminder.
HTH
Willie

 

[edrocket]

I'm having a very similar issue that just arose on my '03 w/ only 45K miles. When engine temp gauge peaked, i popped the hood & engine did not seem overly warm or over heating?

 

[Willie Williford]

Need more info....... Overflow bottle full/empty, Hoses have pressure on them, Heater working, radiator fluid level, etc. etc.?

Willie

 

[edrocket]

I'll check those this evening & report.

 

[AbCaRed00]

When engine temp gauge peaked, i popped the hood & engine did not seem overly warm or over heating?

when I had a air blockage due to a throttle repair inadvertently loosing rad fluid the radiator was cool to the touch.
This was due to lack of circulation through it and low level within it.

I could see temps spiking up on the obdiicc gauge with warning alarm sounding for a few secs then temps were back to normal while the stock gauge was normal. P&G'd home and air bled and no issues with spiking temps..

 

[edrocket]

I changed out the thermostat this weekend. Car heat spiked again around 55 mph twice today then went down to close to normal when i pulled over and was at 25 mph. At idle, car is running at normal temp - not over heating. Took car home & parked it. Heater hoses are hot & was getting heat this morning. Previously i was not. One thing i did notice, my radiator fans are not on/working? Think this might be the issue now. Might of had a sticking thermostat also. Known issue w/ fans or relays going on these?

 

[Willie Williford]

If you have "air" in the system, the radiator fan WILL NOT work. It is controlled by the sensor that only reads coolant temperatures, not air temperatures.......Period.
(From many personal experiences)

HTH
Willie

 

[AbCaRed00]

Did you top up and bleed the air properly after you changed out the thermostat?
It's reasonably easy to do:

How does your coolant overflow container look?
That's the way to top up level if required normally; coolant backflows to radiator via suction when cooling down . A small amount of air can get burped out via the overflow container as well, then just top up again.

 

[edrocket]

My coolant overflow is full. Coolant is very clean/green looking. Thanks for the burping video, i did not do this. Will do it tonight.

 

[talonmike]

Wow! how much time you took to do this video?

Very nice

 

[Willie Williford]

edrocket;

If your overflow bottle is "full." That is wrong.
There is a min and a max level line on the bottle.
Fill it to the max level on changing the coolant and burping.

HTH
Willie

 

[AbCaRed00]

Wow! how much time you took to do this video?
Very nice

Thanks! It took about 10 or 12 hours est. time over a week in several sessions. Most of the time spent was adding the annotations overlaying the screen.
The production was a learning curve and fun to make using mac's iMovie application; 'Gimp' graphics for still images etc; then some editing within YouTube for the annotations.
Glad you enjoyed it and I hope it helps!

 

[Jivko57]

thanks, great video!

 

[edrocket]

Update: I burped the cooling system & ya it works! Drove it after the first burping/bleeding & the temp went just a bar or 2 above normal. Went back home and bled again & it's running at normal temp all the way to work! Thanks Williford! Plus my heat works normal again! So issue seems it was a sticking thermostat in either position at times causing no heat or the temp to spike every so often in the morning after starting out. This sounding board here on this site is great. You guys know what you are talking about. appreciate the help & the time that AbCAred00 took to create the burping video & Williford to help diagnose. I love my car again.