No heat at idle

[keets]

Hello,

I'm trying to figure out what kind of heating issue I have. My 2002 Pathfinder with climate control will only blow heat when the engine above idle. If it's not, it blows cold air.

I've been searching and don't see any similar issues.

Any ideas?

Thanks,

[Towncivilian]

I assume the engine is at operating temperature when the issue occurs?

Your heater core may be clogged or partially restricted. When was the last time the cooling system was flushed?

[lzrj]

Just ran across this problem with my son's Eclipse. It would heat while driving but at idle would only blow cold. The first fix is to see if you are low on coolant (easy fix there). Low coolant level will not make it to the heater core at idle but will when the water pump starts working harder at higher engine speed. If coolant is not low then may have an air bubble in the heater core. You can jack up the front (or use ramps) to help get the air pocket out. Rev engine with radiator cap off. You can also squeeze on the coolant hoses too to help get any air out. If still no hot air then your heat core is probably starting to become or is clogged with debris and may need to be replaces. I'm no mechanic so there could be other issues and or solutions to this as well.

[Chuck Tribolet]

Also, there are one or two places to bleed air from the cooling system. On an '01 there's one at the top center of the firewall. It's a rubber cap
secured by a Jesus clip. The FSM shows a second one at the front of the engine, but my stick shift '01 doesn't have that one. Be careful with the
Jesus clip so doesn't go flying off.

Chuck

[yeldogt]

Did you do any maintenance or repairs to the system recently?

[604-Allstar]

I've got this same problem on my 2001 QX4 and was wondering if you ever found a solution to the problem?

I did just change the radiator but to be honest don't know if the problem excited before the change as just bought the car.

Any help would be great.

Cheers

[Towncivilian]

Inspect your radiator cap following this TSB. Replace with a new OEM one if necessary.

The heater core may be blocked. Feel the heater hoses at idle and see if they are hot.