Q: Truck is overheating and the heater is blowing cold air.

asked by on

It started overheating and the heater blows cold air. Yesterday I replaced water pump and thermostat, same problem. The upper radiator hose is hot and the lower radiator hose is cold.

My car has 180000 miles.
My car has a manual transmission.

Hi there. There is a blockage in the engine preventing the engine from cycling the coolant. If there is a new water pump and a new thermostat, then the coolant should be cycling. Check the radiator for any blockages. Drain out the coolant into a clean container and move aside. Then remove both the upper and lower radiator hoses on the radiator. Put a garden hose on the top of the radiator and fill up the radiator. If nothing comes out of the lower radiator port, then the radiator is plugged and needs replaced. If the water flows smoothly through the radiator and comes out, then remove the thermostat and put the hose where the thermostat was and see if water will come out of the lower radiator hose. If nothing comes out, then there is a blockage in the engine preventing the coolant from moving. If water comes out smoothly, then the thermostat was installed upside down. If you need further assistance with the engine coolant not cycling, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Truck is overheating and the heater is blowing cold air.

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: Brake dust

Asbestos was, and in some cases is still, used in the brake lining and clutch materials on many modern vehicles. It offers good strength, temperature, and chemical resistance and is cheap compared to other materials that are used for the...

Q: My 2012 Scion tC will over rev when I'm trying to accelerate.

If your clutch is slipping you will be able to hear the engine rev, and the tachometer rise without any apparent acceleration of the car. It tends to happen in the higher gears because that is when the load on...

Q: Q: engine overheating.

Hi there. When an engine is overheating your would need to check the coolant to see if its low or not the correct temperature rating. If the coolant is good and rated to the maximum temperature, then the radiator could...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...