The Nissan Path

Can anyone help me with this please. There is no warm heat coming out in my Pathfinder 2002. What could be the problem?

Assuming the heater fan is working, it could be a stuck open thermostat, low coolant level, air pocket in the heater core, or an air mix door that is not opening, which can be due to a non-functioning mode door actuator.

Is there a way to get the air out of the heater core or try to get air out of the heater core, without draining and flushing the system?

There are several ways. For starters, turn the heater on and to the hottest setting. Raising the front end of the vehicle helps a lot. You can do this by putting driving the vehicle up on a set of car ramps or by jacking up the front of the vehicle. For me, the easiest way is to use a "spill-free" funnel, which is made by Lisle and several other companies. The spill-free funnel has attachments that allow you to connect the funnel directly to the radiator opening and partially fill the funnel with coolant, which holds about a quart. Pinch off the return hose to the reservoir and start the engine and run it until the thermostat opens and no air bubbles can be see coming up through the radiator into the coolant in the funnel. The kit includes a stopper to make removing the funnel less messy. Another method is to use a brake shoe horseshow clip (like those used to secure the parking brake lever onto the aft brake shoe) and slip it under the valve of the radiator cap so it won't hold pressure. The air bubbles will then push out and into the reservoir. Raising the reservoir above the radiator helps, which might be difficult in an R50. If you don't want to do all that, loosen the radiator cap and raise the front of the vehicle and let the engine run for approx. 30 minutes. Make sure the coolant is reaching normal operating temperature on the gauge (should be approx. in the middle); a gauge needle that consistantly runs on the low end of the range is usually an indication of a stuck open thermostat. Never remove the cap on a hot engine!

For the spill free funnel:

http://www.walmart.com/ip/Lisle-Spill-F ... 0003260530