So I noticed the other day when it was very cold out, my heater was blowing luke warm air when idling.
When you drove it got hot like it was supposed too.
So I decided to replace both thermostats in the car thinking it would solve the issue.
No real significant change. when idling. A little better but it is also warmer out.
My heat gauge is normal and not overheating.
The car has 375 Km on it.
I'm going to replace the water pump as it old.
Is it possible the impeller is worn and circulating the water enough at low RPMs?
Heater core partially plugged, but it gets hot hot when driving or higher rpm from idle? Doesn't make sense
I pulled the plug off my ac compressor so it wouldn't come on.
I did add some Kseal stop leak to the rad 8 months ago as i seen signs my head gasket could be leaking
Anyone have thoughts?

Thanks Jeff

 

What you describe is normally associated with impaired circulation in the heater core.

The reason it warms when driving is that the water pumps puts out more pressure when it turns faster.

So it could be a water pump problem, but it's difficult to imagine what would cause the pump to degrade that much, outside of severe corrosion--which you would notice in other areas first.

Stop leak can eventually plug up smaller passages and the heater core has small passages.

 

X2 restricted heater core. You could try disconnecting both heater hoses and back flush the heater core with a garden hose. I had an old acura Integra that i had to do this to at the start of every winter for several years.

 

Thanks everyone , I will do a back flush.
Going to change the water pump because of its age and kms on it as well. Do the tensioner and belt as well.
Merry Christmas

 

CRC ThermoCure is a very effective rad cleaner BUT seeing that you live in a cold climate you'd have to wait to use it as it only works with water over a few days.

A sign of a restricted heater core is both heater hoses staying around the same temp as the core isn't transferring/exchanging the heat out.

 

This was a known issue on these vehicles when new. See the TSB and follow the procedure.

You didn't state if you have the 4 or 6 cylinder engine. The v6 were more difficult to bleed than the 4 cylinder, and more likely to get an air pocket in the heater core too.

Since you've used a stop-leak product, be sure to remove and clean the overflow bottle and hose. Stop-leak will collect at that location and prevent coolant from moving easily into and out of the overflow bottle, compounding your problem

Here's one exception I have with the procedure... When bleeding the cooling system, you do not need to have the blower on HI and the temperature set for hot. These vehicles do not use a heater control valve, so coolant is flowing all the time. Running the fan on hi in your climate will never allow the thermostat to open to burp the air out of the system. The engines in these vehicles do not generate a lot of heat when running with no load.

The Altima (and Maxima) heater core from this generation is flat and the inlet and outlet pipe come in from the side, so it is very hard to get air out of the heater core. Pay attention to the bulletin instructions to raise the front of the vehicle. I used to just use a floor jack under the sub-frame on the passenger side front of the sub-frame since that also put a bit of left-to-right angle on the heater core to help it burp.

Good luck!

 

I have a 2.5 L 4 cyl Eng
i Will jack up up the car and try the wire truck under the cap when I bleed the air out.
thanks for the info
Jeff