Heater blowing cold air hardly any heat

TARADOME

MEMBER
2003 CHEVROLET S-10
4.3L
6 CYL
2WD
AUTOMATIC
70,000 MILES

It’s about 7 degrees here. I had not started my truck in about a week prior to this. I started my truck and let it run for about 15 minutes then drove it around. It was a little hesitant to start but started. Heat worked. Everything was all good. I left the heat and radio settings in the on positions when I turned the truck off for the night. I didn’t leave a dome light on the doors were all shut. There wasn’t anything running the battery down that I know of. The next day tried to start the truck and there was no power. Dash and dome lights came on. Click click. Left it alone and didn’t charge it. I did turn the heat and radio off before taking he key out of the ignition. This morning, a day later, first try, the truck started right up. Drove it to and from work with no starting issues. Halfway to work I’m still freezing. The air is cold from the vents. Blows great. If I have it on the front windshield setting the air feels barely warm. It blows real cold air if it’s sat on any other setting. I figured the air was a little warm blowing from the windshield setting because of the heat off the engine. I drove it almost half the day and it never warmed up. Temperature gauge stays below the half mark. I don’t know if all this is correlated or not. Has anyone heard of anything like this? Where do I start looking for the problem?

2 Replies

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

The first thing to check is if the engine coolant is low. If it is, that can cause the heat problem. Take a look through this link and let me know what you find:

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

Let me know,

Take care and God Bless,

Joe

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Thursday, February 18th, 2021 AT 7:19 PM

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,

|I wanted to add a few additional thoughts. If you are not getting heat, pay attention to the temperature gauge in the vehicle. When it gets cold, a faulty thermostat can prevent the engine from reaching operating temperature. If that is the case, you won't get heat. IF you find it isn't warming up, here is a link that shows in general how it's done:

https://www.2carpros.com/articles/replace-thermostat

Next, if it is warming up properly, try this. Start the engine and allow it to reach operating temperature. While it warms up, make sure the heater is on high. Once temp is reached, feel both heater core hoses under the hood. They will run to the firewall. If you look at pic 1, I highlighted what to look for. One is a supply and the other a return. Both should be hot.

If you find one is hot and not the other, the heater core is plugged. Here is a link that explains how to flush a cooling system. You will need to remove the two hoses first. Then, using a garden hose, flush one direction and then backflush the opposite way until the water flows clean.

Now, if both hoses are hot, then heat is in the vehicle. The blend air door is likely the concern. The blend door is responsible for the air temp entering the cab. Here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/replace-blend-door-motor

Here are the directions specific to your vehicle. The attached pics correlate with the directions.

__________________________________

2003 Chevy Truck S10/T10 P/U 4WD V6-4.3L VIN X
Air Temperature Actuator
Vehicle Heating and Air Conditioning Air Door Actuator / Motor Service and Repair Procedures HVAC System - Manual Air Temperature Actuator
AIR TEMPERATURE ACTUATOR
AIR TEMPERATURE ACTUATOR REPLACEMENT

REMOVAL PROCEDURE
The air temperature actuator is located on the top right hand side of the HVAC module.
1. Remove the instrument panel carrier.

Pic 2

2. Disconnect the electrical connector (2).

pic 3

3. Remove the air temperature actuator retaining screws.
4. Remove the air temperature actuator from the HVAC module.

INSTALLATION PROCEDURE

pic 4

1. Install the air temperature actuator to the HVAC module. Ensure that the actuator is seated on the locating tab.
2. Install the air temperature actuator retaining screws.

NOTE: Refer to Fastener Notice in Service Precautions.

Tighten
Tighten the screws to 1.9 N.m (17 lb ft).

pic 5

3. Connect the electrical connector (2).
4. Install the instrument panel carrier.

___________________________________

I hope this helps. Let me know if you have other questions.

Take care and God Bless,

Joe

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