No Heat - heater not working?

Might want to inspect the heater hose and heater core could be clogged-up, heater control valve is normally attached to the hose-could be an air mix/blend door not opening due to an actuator being defective

This guide can help us fix it

https://www.2carpros.com/articles/car-heater-not-working

Please run down this guide and report back.

Hope this helps

BASIC HEATER SYSTEM TROUBLE SHOOTING CHART
CONDITIONPOSSIBLE CAUSE

Insufficient, Erratic, or No Heat

. Low Coolant Level
. Incorrect thermostat.
. Restricted coolant flow through core.
. Heater hoses plugged.
. Misadjusted control cable.
. Sticking heater control valve.
. Vacuum hose leaking.
. Vacuum hose blocked.
. Vacuum motors inoperative.
. Blocked air inlet.
. Inoperative heater blower motor.
. Oil residue on heater core fins.
. Dirt on heater core fins

There is a vent door called a blend air door. Based on its position determines if you get heat, AC, or fresh air. It is located near the heater core. Check that to see if it is working.

Heater blows but not as high and not hot as it did last year. My chevy blazer is an LS 10 Limited edition/ 4door/ 4x4/ 6 cly. Does it have a Cabin Air Filter? Or, I have lots of dogs in and out of my veh on a daily basis. I've had the blazer since 2002.

There is a number of components that can cause low heat performance and blower operation.
This particular system is set up with the evaporator first and then through or around the heater core. So air has to go through the evaporator first and then blow through or around the heater core. I suspect your evaporator fins are restricted because your not getting enough volume of air out of the dash vents and the temperature has decrease as well. Unfortunatly, gaining access to look at the evaporator is going to take some time due to having to remove components to gain access to see (if you have access to a borescope this will allow you to inspect the evaporator fins a bit easier) the evaporator fins. I think removing the blower motor and with a flashlight and a mirror you should see the fins once removed.

Your vehicle is not equipped with a cabin air filter.

As for the temperature blowing out the dash vents. Here are some possible causes for low heat output: a weak thermostat opening longer or stuck open will reduce the amount of heat stored in the cooling system because the cooling system is circulating constantly due to the open thermostat. Restricted or plugged heater core will reduce heat exchange into the passenger compartment. There are doors behind the dash that direct air blown by the blower that could be broken, stuck or the vacuum operated valve that controls the door could be stuck or leaking causing the door to no move when commanded to any more. A over-concentrated coolant/water mixture will not transfer heat as well or in other words if you have more coolant to water the heat will not be carried sufficiently (50/50 mixture is ideal in moderated temperatures. A 40/70 mixture is suggested in cold climates such as Alaska but no more than that). Restricted evaporator/heater core fins will reduce air flow and temperature by plugging fins and insulating these heat exchangers.
I hope this help you, let me know if you have more questions.

Is the engine running at a normal operating temp? Also, one heater core hose should be a little cooler that the other but not much. Have you tried flushing the heater core? It may be partially plugged.

Let me know.

Joe

Sounds like a broken reaction shell in the transmission.I recommend purchasing an upgraded Beast Shell. You can find them for around $55.00 on Ebay. This part will be less likely to fail in the future.

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are.

The temperature is controlled by the use of an air mix door that is operated by an electric motor/actuator. This door can be jammed or the actuator can be inoperative or have stripped plastic gears internally.

Try to back flush the heater core and make sure it is not plugged. Some times you have to do a super flush on the heater core to clean it out. Prestone makes a flushing kit that works great for this

Good morning

Possible causes:

1. Air in the system.
2. Thermostat.
3. Heater core clogged.
4. Blend door inside the truck not working.
5. Failed head gasket from overheating.

Roy