Q: My Chevy blazer is overheating and the heater started blow cold air but now doesn't work at all what could that be?

asked by on

About 2 weeks ago my blazer started overheating but as soon as it got to red it would drop back down once the fan kicked on and then about 2 days ago the heat stopped working and blowing cold air out instead now the heat doesn't work at all and its overheating within 2 minutes of driving. And once it gets to red it makes a ticking noise.Please help!!!

My car has 146000 miles.
My car has an automatic transmission.

The heater not working in some cases may be related to the overheating problem you are also having. This may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. When the cooling system is not properly circulating coolant through the motor, this results in the warm coolant not being pumped through the heater core properly in order to warm the inside of the vehicle.

Engine overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. As mentioned above, this also restricts the warm coolant from flowing through the heater core which uses this to blow warm air into the cab of the vehicle. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. My Chevy blazer is overheating and the heater started blow cold air but now doesn't work at all what could that be?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Service 4 wheel drive light is on

Hi there. A faulty solenoid or motor on the transfer case, an inoperative front differential actuator, or simply a bad switch could all cause the 4WD light to illuminate on your dash. It's a good idea to have an inspection...

Q: The air conditioning, heater, and defroster are not working.

The symptoms you are experiencing can be caused by a few different things. If you are hearing a gurgling noise and your heater is not providing heat, then I would check the engine's coolant. If the coolant is low, it...

Q: Jeep won't shift from second to third

The information provided for your Jeep Grand Cherokee is limited so it is difficult to point you in the right direction. However the symptoms lead me to believe that your vehicle may have put itself in “limp mode”, meaning that...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.