Water gurgling in heater, heat is warm, air is very light coming out of the vents, sometimes air goes cold then comes back warm.. a bump will make it go cold

Marvin

• 85242 Answers
• Posted on Dec 12, 2008

SOURCE: heater does not blow hot air on full heat setting

the problem is caused by the motor that operates the air temp blend door motor in the heating ducts, it blends air between AC and heater core tro give desired outlet temp.

SOURCE: 2004 Chevy Silverado Heater blows cool air

Check blend door actuator for operation

SOURCE: Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

SOURCE: Rear heater blows only cold air no matter what the

If this is equipped with a rear heater core it is probably plugged up and needs to be disassembled and cleaned out

George Hels

• 528 Answers
• Posted on Nov 29, 2010

SOURCE: heater only blows Very luke

Read all of these instructions before starting this job.
First test your heater core for flow by disconnecting both heater core hoses from motor and forcing air from an air compressor into one of them watching for flow from the other. If you have no flow then you may need to backflush your heater core - it is possible you have blockage in it. Your local auto parts store has a backflush kit you can buy that will have a backflush valve ( to be added to your supply heater core hose ) and an additive to put in your coolant system. The kit will not include new coolant so you will need to get that too. Install valve and connect a garden hose.Run motor specified time in the kit. Remove lower hose from your radiator and turn on the water from the hose full blast. Watch the coolant coming out from your radiator to see if any chunky stuff comes out - also watch for the color of the flow. Run water until it comes out clear, then shut off water and disconnect garden hose. Allow system to drain, reconnect radiator hose and cap flush valve. Refill coolant system, turn heat on high and run motor until it is warm. Top off coolant in radiator ( be careful - the pressure may cause coolant to spray out when you remove cap - put a rag over the cap before you remove slowly). If you do not have warm air at this point you may have a bubble in the heater core and may need to block rear wheels then raise the front of the vehicle until the radiator cap is higher than the heater core. Restart vehicle and turn heater on high . Check coolant level in radiator and top off, then cap radiator and shut off motor. Lower vehicle and start again with heater on high. If you still have no heat then your heater core may be plugged. To check, remove both heater hoses from motor and force air from an air compressor into one of the hoses, watching for flow from the other hose - if no flow then core is plugged and needs to be replaced, but if you have flow then you still have an air bubble in the system and need to purge using the above steps until you have heat.
Hope this helps and please rate my solution - good luck!!