There are several different reasons why your vehicle may not have enough heat.  Some of them may be an easy fix, others may be a little more involved.  The first and easiest step would be to check the coolant level in your vehicle.  The heater core is typically the highest point in your cooling system so if you are a little low on coolant the heater core is the first to drain.  Be careful to only check the coolant level in the radiator when the car is cold, the coolant in your vehicle is a pressurized system and will cause severe burns.  If the system is low on coolant add a 50/50 mixture to the top of the radiator.

Not Enough Heat in my Car, Heater Core?

A dirty cooling system can restrict the heater core’s performance.  Any amount of “stop leak” may cause a loss of heat produced by the heater core.  One way to tell if a heater core is partially plugged up is to locate the heater hoses that carry coolant to the heater core.  They are two black hoses approx one inch in diameter at the rear of the engine going into the firewall.  Set the temperature in the vehicle at hot, with the fan off.  When the vehicle is at operating temperature feel the two hoses, the should be the same temperature.  If one hose is noticeably hotter then the other then the heater core may be partially plugged or restricted.  If this is the case the heater core may be able to be flushed out with water and air pressure, sometime this will clear up a heater core enough to get good heat.  The overall condition of the cooling system should be addressed at this time, a coolant change and poss flush of entire system should be considered.


If you have an older vehicle, it may be equipped with a heater control valve.  This valve is located in line of the heater inlet hose.  Sometime these valves will freeze up and not switch back and forth from open to close.  If the valve is stuck in the closed position it will block coolant flow to the heater core and not allow hot coolant into the heater core.  If this is the case the valve can usually be freed up with some penetrating oil and physically moving the valve back and fourth.

If the engine temperature is warmer then normal but still have no heat.  This may be caused by a stuck closed thermostat or other restriction in the cooling system.  If this is the case the thermostat will have to be replaced.  This can lead to engine damage if left alone.  The engine can build up huge amounts of heat and overheat the engine which can lead to engine damage.

Heater Core Replacement

Heater Core Replacement

The air get cooler when I stop and heats up again when I drive.  This symptom can be caused by a water pump starting to go bad.  If the impeller in the water pumps starts slipping or is getting rotted away it will not pump enough coolant thru the system.  The only solution for this is to have the water pump replaced.  You may want to address this concern because if left unattended can lead to overheating and ultimately engine damage.


The vehicle take long periods of time to warm up.  This is usually caused by a defective thermostat that is stuck in the open position.  A properly working cooling system will achieve operating temperature in approximately 6-8 minutes.  The thermostat will have to be changed in order to correct his concern.

If the cooling system is functioning properly, and you have a newer vehicle.  Hot and cold blend doors or blend door actuator motors may not be working properly.  The blend doors control the temperature in the dash board by moving back and fourth and controlling the amount of heat allowed in the passenger compartment.  With temperature blend doors coolant is constantly flowing thru the heater core, the blend doors direct air around the heater core.  When more heat is commanded the blend doors allow more air to flow thru the heater core.

These are just some of the common causes of no heat in a vehicle.  There are other concerns that may be tougher to diagnosis.  If you want an experts opinion feel free to contact us any time, we’d love to check out your vehicle.  We will give you an estimate before any work is done on the price of the repair.  Thank you for reading, please feel free to call us:  Triangle Auto Service, 4060 N. Elston, Chicago Il. 60618, (773) 539-5858