2000 Nissan Quest. Is blowing cold air. Heat was working yesterday

Your thermostat is stuck opened,not letting your coolant to heat up Sandra,need to replace.

Yes it's very true, change the front one and you will not have any further problem

If you need further help, I’m available over the phone at https://www.6ya.com/expert/michael_2094e122cc46f24c

You will need to bleed the air out of the system there should be a bleeder where the top hose connects to the engine

I believe they only stopped using freon last year in vehicle ac's. That is what it sounds like is the problem.

you are low on freon. Front needs more freaon for fixed orifice tube system.

http://groups.yahoo.com/group/villagerquest/

your air con needs re gasing

bad fan blower. have you tried it on diffrent speeds? or see if the heat blows out?

sounds like a damper door in the front not working properly, these are actuated by the front temp control, the door is operated by either a manual cable, and electric actuator, or vacuum. I hope this helps you zero in on your problem. Merry Christmas

Check out Thermostatic Expantion Valve

You most likely have an air pocket in the cooling system. The heater core on these vans is much higher than the engine and they can be tough to get all the air out of them.

Make sure the coolant in the radiator is full when engine is cold- also fill the overflow bottle to the top. Chock the rear wheels. Jack up the front of the van as far as you can and support with jack stands. Run the engine until it's warm and then hold the RPMS at 2000 for about 5 minutes while checking for heat inside the cabin. You may hear some funny noises like something is trying to come through the firewall forcefully! That's the air pocket moving... you might not hear this also. Once you have good heat inside, let the engine idle- if the air coming form the vents cools off after a couple minutes, the air is still there- keep doing this until the air is hot coming from the vents at idle for more than a couple minutes. Once you have good heat, turn the engine off and let the engine cool completely- at least a couple hours... you will most likely see the level in the overflow drop dramatically. Lower vehicle and make sure overflow is at COLD FULL mark.

Newer Altimas also had a similar situation in which heat would go away at idle- usually not a problem with an air pocket, but Nissan has a bulletin out on putting the correct concentration of coolant/water in the system- these cars are very sensitive to changes in coolant mixture concentration.

Nissan Scope Technician- 10 years with Nissan