I have backflushed my heater core, and the hoses get hot. Water from heater core flowed easily and clear after the brown crud was flushed out. But yet still no heat. The a/c works great, i can hear the blend door moving when i mess with the controls, radiator is clean. I have not yet checked the thermostat and water pump, but i believe problem is that the heater core is bad. what do you think? can help me?
Re: Cool air blowing from heater, even when on high.
If the heater core is bad, it will leak or not flow water. even tho you can "hear" the blend door working, it may not be actually moving inside the box. check to see if the actuator is connectd to the blend air door. You may be hearing the actuator moving but not the door.
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Feel your heater hoses. If both are hot, the heater core is circulating coolant, and the thermostat is not a problem. The door controls in the heater case need attention.
If only one heater hose is hot and the other cool, look for a water valve in the heater hoses-may be closed. Or the core has an air blockage or blockage-try to backflush it with a garden hose.
If both heater hoses are cool (on a warmed up engine), then it could be thermostat is stuck open.
sounds like there is a blockage in the heater core. I would sugest taking the hoses loose and using a garden hose see if water can flow thur the core. If it dont flow thru the core you might have to replace the core.
It's possible that the heater core is plugged internally with crud and this is preventing the hot water from flowing through it which will cause one hose to be hot and the other to be much cooler. If the temperature gauge is indicating that the engine is reaching normal operating temperature and the heater controls are functioning properly then you may need to have the heater core backflushed or replaced. Hope this helps and good luck!
i wish you luck but is the temp staying in the usual place on the meter... could be as simple as a heater coil. or maybe the electronic control is not changing to flow water to heater core.. check engine light on?: turn heat on off on off on off to try to get it to change flow.. good luck
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!!
Try backflushing the heater core - sometimes they plug up and will not allow the water to flow. You can go to an auto parts store and get a backflush kit which should include a backflush connector, clamps and an additive to put in your coolant system as well as directions to install connector. Pour additive into your radiator after you install the connector and use some vice grips to pinch off the heater hoses so you don't lose all of your coolant when you cut the hose to install the connector. Clamp off both hoses to prevent premature drainage and make sure you drain radiator and coolant system afterwards, adding the proper mix of antifreeze and water when you're done to prevent engine damage during a freeze. Good luck!!
try backflushing the heater core,remove heater coolant hoses and flush both ways with a garden hose,do you have a air compressor ,blow water back through heater core both ways,this asuming that all valves are working allowing coolant to flow and all air doors in car are opening,if so this fix has worked many times for me in older cars note works better to hook water hose to hoses or a short peice of hose on heater core,good luck
Your '99 Blazer does not have a water valve. Just a temp. blend door. In other words, hot water should be flowing through the core at all times. Like the other techs said, make sure you are getting the whole system full of coolant. You might even try disconnecting one hose, and pouring water into the heater core itself. On most of these year models, if you listen, you can hear the rush of water through the core when you lightly rev the eng. I have replaced 3 heater cores just last year on '96-'99 Blazers. They clog easily. YOu can blow or flow water through them, but if they don't flow freely, I mean without any restriction whatsoever, they will not get as hot as you want. The thing is tiny!
Here's an easy test: Run engine until temp gauge reaches normal: around 180-200 degrees. Reach back to the firewall and grab both heater core hoses. Are they both about the same temp. and HOT? THey should be. If one is much warmer than the other. You are clogged enough to suffer in the winter. And from what you said: "Brrrrrr" You are getting poor performance out of your heater.
BE sure to check that the blend door is working. Is it cool when you set temp to cool? Blazers go through way more heater cores than they do blend doors, so I'm betting your core is either empty, or clogged. TaterTodd
The heater in your car depends upon a flow of hot coolant going through the heater core in order to get hot air into the car. If the heater core is partially plugged, it will restrict the flow. If you have a head gasket that is putting exhaust into the cooling system, it will eventually get into the heater core. When this happens there is no coolant in the heater core to make the air warm. If the water pump vanes have corroded away the result will be very poor coolant circulation causing the heater to not blow hot air. If your car is equipped with a heater control valve that is not functioning properly, the coolant flow will be restricted. One or a combination of these factors is likely the culprit in your case.
if the car is not overheating, the thermostat is working fine.... replace or flush the heater core multiple times to try and eliminate sediment build-up.